08:45:00 AM 11/16/00 - Greetings from DFC Executive Secretary and Chair of Local Committee - Pister, EP^*1  (1 Desert Fishes Council, Bishop, California)

08:50:00 AM 11/16/00 - Welcome to Furnace Creek and Death Valley National Park - Martin, R^*1  (1 Death Valley National Park, Furnace Creek, California)

09:00:00 AM 11/16/00 - Desert fishes research and management in Texas during 2000 - Garrett, GP^*1; Edwards, RJ²; Allan, NL³  (1 Texas Parks & Wildlife, HOH Research Station; 2 University of Texas-Pan American, Department of Biology; 3 U.S. Fish and Wildlife Service)

Devils River minnow (Dionda diaboli): An intensive inventory of the Devils River was completed in July 2000. This data, coupled with results from the artificial stream studies, will be used to determine habitat requirements and conservation needs. Pecos pupfish (Cyprinodon pecosensis): The last location for Pecos pupfish in Texas, has suffered greatly from the drought and little water remains. A salt cedar eradication program was initiated by the Fort Worth Zoo in order to preserved what little is left. A brood stock from Salt Creek was moved to the Fort Worth Zoo as insurance against total loss. Pecos pupfish from Salt Creek were also stocked into a 1.7 hectare, ciénega-like pond constructed under the Landowner Incentive Program, and a first-ever conservation agreement with a private landowner in west Texas. Comanche Springs pupfish (Cyprinodon elegans): Ongoing surveys at the San Solomon Ciénega indicate large populations of both Comanche Springs pupfish and Pecos gambusia (Gambusia nobilis). Unfortunately, nearby Phantom Lake Springs have failed. Leon Springs pupfish (Cyprinodon bovinus): Phase II of the Diamond Y Draw renovation was completed in March 2000. Results indicate the project has successfully repatriated Leon Springs pupfish to its only remaining habitat in the wild. A continuous flow monitoring gage has been installed at Diamond Y Spring to document springflow trends. Exotics: The loricariid vermiculated sailfin catfish, Pterogoplichthys disjunctivus, is now apparently established in the San Antonio River and elsewhere in Texas, including the San Marcos River, which contains four federally endangered and threatened species and the Buffalo Bayou drainage in Houston. This species has also been found in the Tampa, Florida, area where it is commonly raised in tropical fish farms. The species is native to the Río Madeira drainage (Amazon River basin) of Brazil and Bolivia. It is presently unknown what impact this new introduction will have, but may impact native species that utilize algae and other bottom foods. This brings the total number of introduced South American armored catfishes established into Texas waters to two species.

09:15:00 AM 11/16/00 - Overview of native fish research and management in the Upper Rio Grande Basin of Colorado and New Mexico during 2000 - Swift-Miller, S^*1; Chubb, S²  (1 U.S. Forest Service, Rio Grande National Forest, Monte Vista, CO; 2 U.S. Forest Service, Southwestern Regional Office, Albuquerque, NM)

Research and management activities in the upper Río Grande basin of Colorado and New Mexico focused this year on securing instream flows, construction of a new aquatic species hatchery, population surveys and monitoring, fish migration barrier surveys, collection of genetic samples, restoration and habitat improvement projects, educational activities, initial planning for the development of interactive native fish geospatial database, and drafting a Río Grande Cutthroat Trout (Oncorhynchus clarki virginalis) Management Plan. In Colorado, 2000 was highlighted by the signing of an historic decree in Colorado’s Water Division 3, granting the Río Grande National Forest Federal Reserve Water rights. The decree is the product of 6 years of intense negotiations between the San Luis Valley Water Users, the Department of Justice, and the Colorado Attorney Generals’ Office. This is the first settlement of its kind in the nation, and provides a level of protection previously unachieved anywhere, requiring the protection of base and high flows in all streams on the Río Grande National Forest. The flows protected, on average, will require over 90% of flow to be maintained in-stream.

Another highlight was this year’s opening of a new Aquatic Species Restoration facility in Alamosa. The Colorado Division of Wildlife, in cooperation with the Colorado Water Conservation Board and Go Colorado (GOCO), sponsored the new facility, dedicated to Colorado’s rare and imperiled native aquatic species including fish, amphibians, and mollusks. Río Grande sucker (Catostomus plebeius) and Río Grande chub (Gila pandora) are currently being reared at the facility, as are many other species from the Colorado, Arkansas, and Platte drainages.

Other activities in Colorado included Río Grande cutthroat trout spawntaking operations (over 90,000 eggs collected for hatchery rearing); stocking Río Grande cutthroat trout into over 40 wilderness lakes; monitoring of historic and translocated populations of Río Grande natives; conducting habitat assessments and stream improvement projects; constructing a fish migration barrier; collecting genetic samples; removing non-native fish in native fish habitats by electrofishing; and continuing an active public outreach/education program.

The Southwestern Region U.S. Forest Service is funding cooperative studies with the Rocky Mountain Research Station from Flagstaff, Arizona, the Río Grande National Forest in Colorado (Region 2), New Mexico Game & Fish Department, and New Mexico State University to develop an interactive geospatial database that will 1) describe the distribution, status, and co-occurrence of Río Grande cutthroat trout and affiliated native fishes (Río Grande sucker, Río Grande chub, plus others), 2) identify extent and effects of non-native fishes, whirling disease vectors, and land-use practices on native fish species, and 3) assist in locating and prioritizing suitable locations for expansion of native fishes.

In cooperation with New Mexico Department of Game and Fish, the Carson and Santa Fe National Forests participated this summer in the extensive collection of cutthroat trout fin clips as samples for micro satellite DNA analysis.

The Rocky Mountain Research Station personnel from Laramie, Wyoming trained field personnel from the Carson, Santa Fe, and Río Grande National Forests in basin-wide fish population survey techniques. Population survey data were collected in the drainage of a future restoration project planned in coordination the New Mexico Department of Game and Fish. These activities were filmed and shown on a July 2000 “New Mexico Outdoors” television show. Similar population surveys were accomplished in wilderness streams on the Lincoln National Forest and throughout the Río Grande National Forest. The Gila National Forest was completing the final stages of NEPA for a planned Río Grande cutthroat trout restoration project on Animas Creek. The Ladder Ranch (Turner Endangered Species Fund), US Fish and Wildlife Service, and New Mexico Game & Fish are Cooperators. The overall goal is to restore approximately 30 miles of stream to Río Grande native fish assemblages.

The Rocky Mountain Research Station released a progress report on their 1999 surveys of fish migration barriers related to the security of Río Grande cutthroat trout on the Carson and Santa Fe National Forests. During 1999, 25 streams were surveyed. Of those streams, two (8%) were unprotected by migration barriers, ten (40%) had barriers which were considered stable and functioning, two (8%) were found to have non-native trout above the barrier, six (24%) had unstable barriers, five (20%) had culverts that may act as partial barriers, and two (8%) were not defined. A new location for Río Grand Cutthroat trout was identified. Additional barrier stream surveys continued through the summer of 2000 with Forest support.

The Carson National Forest has also 1) continued maintenance of existing fish migration barriers and removal of exotic trout in order to provide protection to Río Grande cutthroat trout populations, 2) conducted population surveys and monitoring of two previous stream restorations which indicated both were very successful, and 3) planted cottonwood/willows in cooperation with New Mexico Trout and Sangre de Cristo Flyfishers, in a Río Grande cutthroat trout drainage.

09:30:00 AM 11/16/00 - Native fish research and management in New Mexico during 2000 - Brooks, J^*1; Propst, D²; Dudley, R³; Hoagstrom, C¹; Monzingo, J⁴; Platania, S³; Smith, J¹  (1 U.S. Fish and Wildlife Service; 2 New Mexico Department of Game and Fish; 3 University of New Mexico; 4 U.S. Forest Service)

Federal water projects have resulted in substantial alterations to aquatic habitats that support native fishes in New Mexico. Every major water course of the Río Grande, Pecos River, Gila River, Mimbres River, and South Canadian River basins is impacted and the native ichthyofauna has either disappeared or is severely altered and threatened with extirpation. Activities in New Mexico during 2000 centered around identification of flow-habitat relationships and habitat-use patterns of native fishes, and implementation of flow recommendations and other protective measures to address habitat and species needs. In montane regions, recovery of native trouts and protection of watersheds to stabilize runoff to lowland regions for protection of warmwater natives are major areas of concentration for conservation of native fish resources.

The declining status and distribution of the Río Grande silvery minnow Hybognathus amarus continued in 2000 as a response to diminishing flows caused by water management activities and dry climatic conditions. Repetitive drying of the river channel downstream of Isleta and San Acacia diversions caused numerous localized extirpation events and resulted in low survival of young-of-year fish. Monitoring efforts demonstrated that Río Grande silvery minnow were largely absent from upstream reaches in the Albuquerque area and loss of fish in downstream reaches during intermittent conditions have combined to result in the lowest ever documented abundance and range. Legal actions between parties either pro- or con-Río Grande silvery minnow protection resulted in short-term agreements to provide surface flows in previously intermittent reaches until the end of irrigation season, late October. While most emphasis has been placed upon implementing protective measures for downstream reaches, additional focus is needed for upstream reaches. Degrading river channel conditions and water quality impacts have resulted in near loss of Río Grande silvery minnow upstream of Albuquerque, thus depriving lower reaches of re-colonization by drifting eggs and larvae. Survival of the Río Grande silvery minnow will require a holistic approach to river channel restoration and not be dependent upon isolated, stop-gap measures in disjunct reaches.

In the Pecos River Basin, a draft final report was provided to the U.S. Bureau of Reclamation for use in providing flows to Pecos bluntnose shiner Notropis simus pecosensis and the associated fish community. The report details flow/habitat relationships and relates to habitat use patterns of resident fishes. Of most importance is providing adequate releases from upstream reservoirs during baseflow conditions and restricting dam-controlled irrigation releases to minimize downstream transport of eggs and larvae of pelagic-spawning native cyprinids. Monitoring of fish community structure and habitat conditions continued during 2000 and the current abundance patterns of Pecos bluntnose shiner are highest since listing of the species in 1987. The recovery plan for Pecos bluntnose shiner is currently under revision. Elsewhere in the Pecos River Basin, the Pecos pupfish Cyprinodon pecosensis remains abundant and concentrated at Bitter Lake National Wildlife Refuge, but may be extirpated from the Pecos River downstream of Carlsbad through hybridization with sheepshead minnow Cyprinodon variegatus. The proposal to list the species as Endangered was withdrawn in favor of the development of a Conservation Agreement between the states of New Mexico and Texas and the U.S. Fish and Wildlife Service.

Activities in the Gila River Basin centered around conservation efforts for Gila trout Onchorynchus gilae and monitoring of spikedace Meda fulgida and loach minnow Tiaroga cobitis populations. Gila trout activities included the successful renovation of White Creek to remove hybrid trout for restocking during October 2000, introduction of hatchery-reared Gila trout into lower Little Creek, transplantation and spawning of Gila trout from Whiskey Creek for introductions into upper Little Creek, transplantation and spawning of wild Gila trout from Spruce Creek for introduction into Dude Creek (Arizona), monitoring and stocking of Black Canyon, and documentation of successful spawning of Gila trout in Mogollon and South Diamond creeks. The Gila Trout Recovery Plan has been revised and is under technical review. Monitoring of spikedace and loach minnow populations documented stable populations in upstream reaches, with nonnative species dominating mid-reach areas near the confluence of the West and East forks of the Gila River. Further downstream, the density and abundance of native species remains low.

Chihuahua chub Gila nigrescens monitoring in the Mimbres River demonstrated persistence of the mainstream population, albeit at a low level. Smallmouth bass Micropterus dolomieu were discovered in Moreno Springs, an important refugial habitat, in early spring and all individuals encountered were removed. Later collection efforts did not capture additional smallmouth bass. In February, 65 Chihuahua chub reared at Dexter National Fish Hatchery and Technology Center were stocked into the Mimbres River on lands owned by The Nature Conservancy.

Río Grande cutthroat trout Onchorynchus clarki virginalis conservation field efforts were compounded in New Mexico by additional procedures within State of New Mexico agency protocols regarding the use of antimycin. As a result, all scheduled stream renovation efforts were canceled during 2000. A management plan was drafted to provide guidance for all agencies involved in management activities. Future projects will be outlined in a five-year operational plan developed through interagency cooperation. An interagency Conservation Agreement and Memorandum of Understanding is awaiting signatures upon completion of the Plan.

 Transport of non-target organisms via hatchery stockings of recreational fishes was documented on several occasions. A variety of fishes, amphibians, and invertebrates have been discovered in warmwater shipments from U.S.Fish and Wildlife Service hatcheries in the Southwest Region during the last two years. Further examination indicated that this is a longstanding issue and failure to eliminate shipments of non-target organisms poses additional risks to native fish conservation. These stockings have resulted in the establishment of several fish and one amphibian species outside native range.

09:45:00 AM 11/16/00 - Upper Colorado River Basin area report - Modde, T^*1; Crist, L²  (1 U.S. Fish and Wildlife Service; 2 U.S. Bureau of Reclamation)

During 1999-2000 several flow recommendations were approved or in the development stage at this writing for several Upper Colorado River Rivers. A synthesis of a five year flow study on the releases from Flaming Gorge Dam was completed by the recovery program which summarized most of the existing information on the large river fishes in the Green River subbasin. This document provided flow recommendations for each season for each three reaches of the river (Lodore Canyon, confluence of the Yampa River to the confluence of the White River, and from the confluence of the White River to the confluence of the Green and Colorado rivers). A flow recommendation was also prepared for the releases from the Aspinall units on the Upper Colorado River. These documents will serve as the template for revised biological opinions on the operation of dams on both rivers. The flow recommendations will alter the current operations of both systems and the Bureau of Reclamation is in the process of preparing an Environmental Impact Statement for each revised biological opinion. A programmatic biological opinion was prepared for the 15 mile reach on the Colorado River and another is being prepared for the Yampa River that will based on a Yampa Valley Management plan. The latter incorporates nonnative management actions together with annual flow recommendations. Proposed recovery goals for the large Colorado River fishes will be submitted by Fish and Wildlife Service to the federal register in September (tentative date). Development of recovery goals was initiated through Region 6, of the Fish and Wildlife Service. Several workshops and meetings within the upper basin recovery program and recovery team provided input into the document, however, consensus among all participants was not achieved. Augmentation highlights in the upper Colorado River basin included the first reintroduction of bonytails, {Gila elegans}, into the state of Colorado. Five thousand fish were stocked in both the Yampa (just upstream from the Green River confluence) an d the Green River (upstream of Lodore Canyon). Bonytails have been stocked in the lower Green River in Utah the last three years. Razorback sucker, {Xyrauchen texanus}, augmentation continues in both the middle Green and Colorado Rivers. At this writing approximately 50,000 juvenile razorback sucker are planned to be stocked between the Colorado and Gunnison rivers in September of this year. Few numbers of larger fish have been stocked into the middle Green River. Last spring more hatchery reared fish than wild fish were captured from the middle Green River spawning area.

10:00:00 AM 11/16/00 - Bonneville Basin annual area report - Andersen, ME^*1  (1 Utah Division of Wildlife Resources)

Steadily increasing water demands from agriculture and the burgeoning Wasatch Front human population are making active protection efforts for native fish species in the Bonneville Basin increasingly important. A great deal of work is being entered into on their behalf, although additional efforts would always be welcome. Multiple agencies, institutions, contractors, and individuals are contributing time and funding to conservation efforts for native fish in this basin. Such cooperative efforts are likely to be critical to any successes that are realized. Listed in order from those that are receiving the least attention to those that are receiving the most, the primary fishes of concern in the basin during the past year are: leatherside chub (Gila copei), least chub (Iotichthys phlegethontis), June sucker (Chasmistes liorus), and Bonneville cutthroat trout (Oncorhynchus clarki utah). Leatherside chub, distributed along the center of Utah and into Wyoming and Idaho, have been the subject of increasing institutional work, which is suggesting that this fish, currently recognized as Gila copei, should probably be recognized as two species, Lepidomeda and Snyderichthys. The former has a more southerly distribution, and the latter is distributed in the northern tri-state area. Least chub are under increasing pressure from non-natives in both their west desert and mountain foothill habitats; non-native control strategies are being developed, and in some cases, implemented. Many conservation actions for least chub also benefit spotted frog (Rana pretiosa), as the two are often sympatric in Utah. The UDWR captured 51 June sucker returning to spawn in the Provo River this year, the most captured over the past few years. June sucker are the subject of a multi-agency recovery program which is accelerating its administrative and technical work. Bonneville cutthroat trout are one species being addressed by a multi-state, multi-agency cooperative agreement, which has defined a protocol for determining genetic purity of cutthroat subspecies. The UDWR has been actively protecting and reintroducing this species along the western aspect of the Wasatch Front. A Bonneville Basin GIS database has recently been completed by a post-doc at USU utilizing the EPA stream identification system. This database, which has been provided to UDWR, should be a valuable tool for managing recovery, monitoring, and conservation efforts.

10:15:00 AM 11/16/00 - Oregon area report - White, R^*1; Young, D¹; Reid, S¹  (1 US Fish and Wildlife Service)

We will give an update on Oregon Area Desert Fish issues. We will discuss the 12-month Finding on Great Basin Interior Redband Trout (Oncorhynchus mykiss sp) and associated research and management activities; proposed changes in Lahontan Cutthroat Trout (O. clarki henshawi) angling regs in Willow and Whitehorse creeks; proposed legislation for a National Conservation Area designation for Steens Mountain area, which would include a permanent ban on geothermal exploration in the area of the endangered Borax Lake chub (Gila boraxobius), and research and management activities associated with Modoc sucker (Catostomus microps) . We will report on any fish kills in Upper Klamath Lake that occur after submission of this abstract, as water quality and weather patterns are lined up for a major fish kill(s) this summer.

10:30:00 AM 11/16/00 - Northern Nevada area report - Cook, AE^*1; Byers, SB^*2  (1 Nevada Division of Wildlife; 2 USFWS, Nevada Fish & Wildlife Office)

An update on northern Nevada desert fish species will be presented. The update will include brief reports on cui-ui (Chasmistes cujus); Independence Valley speckled dace (Rhinichthys osculus lethoporus); Hiko White River Springfish, Blue Link Refugium population (Chrenichthys baileyi grandis); relict dace (Relictus solitarius);Lahontan cutthroat trout (Oncorhynchus clarki henshawi); Bonneville cutthroat trout (Onchorhynchus clarki utah); and Piute cutthroat trout (Onchorhynchus clarki clarki).

10:45:00 AM 11/16/00 - Native fish and amphibian management in southern Nevada - Stein, JR^*1; Heinrich, JE¹; Sjoberg, JF¹; Hobbs, BM¹; St. George, D²  (1 Nevada Division of Wildlife; 2 US Fish and Wildlife Service, Ash Meadows NWR)

Devils Hole pupfish, Cyprinodon diabolis, population counts continue to show a decrease in the population. The last year's counts are as follows: August 1999, 344; October 1999, 328; December 1999, 288; February 2000, 240; April 2000, 190; June 2000, 223; August 2000, 286. The Hoover Dam refugia continues to function properly since reactivation in 1998. Population counts at this site for December 1999, February 2000, May 2000 and July 2000 were 35, 38, 45, and 72 respectively.

The Nevada Division of Wildlife in cooperation with Ash Meadows National Wildlife Refuge are continuing toward removal of all bass from refuge properties. The final step of the process is the removal of the bass from Crystal Reservoir. Ash Meadows NWR staff and volunteers removed 12,470 nonnative fish, crayfish, and amphibians in 1999. A large fire burned approximately 1,500 acres on the northern portion of the refuge removed large stands of tamarisk as well as the remaining native flora community within the burn area.

The winter survey for Pahranagat roundtail chub, Gila robusta jordani, was conducted in late January and early February 2000 and resulted in count of 133 fish, of which 33 were juveniles. This is similar to past winter counts during the last few years. A population count during July 2000, resulted in 138 chub, of which 68 were juveniles. This continues to represents a substantial decrease from the 1998 and 1999 summer estimates. A population survey in June of 1998 estimated 2,849 chub, of which 2,596 were juveniles. The summer count in June of 1999 enumerated 308 chub, of which 132 were juveniles.

Hiko White River springfish, Crinichthys baileyi grandis, monitoring occurred in June 2000 within the Pahranagat Valley at Crystal Spring and Hiko Spring. A population estimate of 6,277 adult springfish was developed at Hiko Spring using mark-recapture. The springfish at Hiko Spring make up approximately 55% of the fish assemblage. The remaining fish species found here are shortfin mollies, mosquitofish, and convict cichlids. At Crystal Spring 350 springfish were counted during a snorkel survey. This count represents a substantial increase from past estimates which were usually between 100 and 200 fish. The exotic aquaria fish at Crystal Spring greatly outnumber the native springfish, but no ration have yet been determined

The White River spinedace, Lepidomeda albivalis, continues to recover in the Sunnyside Creek system. A late summer count in September 1999 enumerated 1,573 spinedace representing four distinct age classes. A count is scheduled for September 2000, and the results will be presented at the annual meeting. As the spinedace population continues to recover from an estimated 20 adults confined to a single spring pool in 1995, the distribution of the species has also increased. A habitat inventory on Sunnyside Creek is currently being conducted for the purpose of determining habitat preferences for the spinedace. The State is currently negotiating a conservation from a neighboring ranch that has a system of springs which connect with Sunnyside Creek. This easement would perpetually protect the springs, surrounding upland plant communities, and assemblage of native fishes. This easement may also allow the repatriation of spinedace, covered by a "Safe Harbor" agreement.

Railroad Valley springfish, Crenichthys nevadae, monitoring was completed in July 2000 with the exception of populations which occur on Duckwater Tribal properties. All of the sampled populations continue to remain at high levels, well above delisting criteria. At Hay Corral Spring the estimate was 1,868. At Big Spring the population estimate was 1,733. At North Spring the population estimate was 2,509. At Reynolds Spring the population was estimated to be 1,135 fish. The population at Chimney Hot Spring refugia was estimated at 3,356.

During a site visit to Big Warm Springs at Duckwater in May, 2000 Mozambique tilapia were found for the first time in the system. No Railroad Valley Springfish were captured at this location after extensive netting and electrofishing. The suspected source of the tilapia introduction is from a fish farm which occurs on tribal properties. The fish farm has been known to only raise catfish in the past and may have expanded to other products. Law enforcement from USFWS and the Nevada Division of Wildlife in Las Vegas are currently conducting a criminal investigation.

Condor Canyon, the only known distribution for the Big Springs spinedace, Lepidomeda mollispinis pratensis, continues to recover from a large fire destroyed most of the riparian and upland vegetation in July 1999. Division of Wildlife survey crews implemented the standardized monitoring protocols in August, 2000 and found that spinedace numbers had slightly increased from the previous August. Population estimates ranged from 4,920 spinedace per kilometer to 200 spinedace per kilometer. Spinedace were found in the upper four of six 25 meter permanent transects.

At the Muddy River Moapa dace, Moapa coriacea, during a survey conducted in March and April of 2000, 940 dace counted. This is similar to 1999 numbers in the reaches surveyed, Muddy Spring, the main stem of the Muddy River, and Plummer Springs were not surveyed. The management focus on the Muddy River has been the eradication of the blue tilapia. Rotenone treatments have been successful at the Apcar tributary and the Refuge springs. A permanent barrier was constructed in July 2000 to prevent upstream movement of tilapia into these treated segments. Virgin River chub, Gila seminuda, Moapa speckled dace, Rhinichthys osculus moapae, and Moapa springfish, Crenichthys baileyi moapae, have also been negatively impacted by the tilapia.

Virgin River native fishes monitoring completed in Nevada by the recovery team in October and April found only four woundfin, Plagopterus argentissimus, and no Virgin River chub. Studies using woundfin obtained from Dexter National Fish Hatchery and Technology Center continued in 2000. In October 1999 a total of 9,275 woundfin were released in Nevada reaches of the Virgin River just below the Arizona border. A portion of these fish have remained in the system resulting in reproduction and recruitment.

A program to repatriate Virgin River spinedace, Lepidomeda mollispinis mollispinis, back into Nevada waters at Beaver Dam Wash has been ongoing for several years. Sampling in April and June, 2000, again found adult spinedace but no recruitment.

Bio/West Inc. continues to survey for razorback sucker, Xyrauchen texanus, on the Lake Mead supported by the Southern Nevada Water Authority. On Lake Mohave, NDOW provided assistance in the collection of 91,000 larval razorback suckers. A portion of these fish were reared at the Boulder City Golf Course ponds and the Veterans Park ponds in cooperation with the Bureau of Reclamation. In 1999, these ponds provided a total of 7,500 fish for repatriation into Lake Mohave.

The Division and cooperating agencies continued to intensively survey the population status, habitat selectivity, movement patterns, and growth rates of the Amargosa toad, Bufo nelsoni. To date over 2,000 individual adult toads have been implanted with PIT tags at 11 survey sites. Recapture rates during the latest surveys were above 50 %. The objective of this project was to quantify the population of Amargosa toad, Bufo nelsoni, in Oasis Valley by using a mark-recapture monitoring program and to create a model for potentially occupiable habitat.

11:00:00 AM 11/16/00 - California State agency report - Miller, R^*1; Threloff, D²; Keeney, S¹; Becker, D¹; Knowles, G³; Reid, S³; Bentivoglio, A³  (1 California Department of Fish and Game; 2 Death Valley National Park; 3 US Fish and Wildlife Service)

A Cowhead Lake tui chub (Gila bicolor vaccaceps) Conservation Agreement and Strategy (CA/CS) has been signed by the private landowners and the State and Federal agencies. The CA/CS has two phases. Phase One (2-3 years) is to acquire more information on the species, its habitat, and its distribution. Phase Two (10+ years) is to develop and implement projects, using the knowledge acquired in Phase One, that will improve the quality and availability of habitat for the species. Preliminary data were gathered in 1999 and 2000 and the US Geological Survey, Biological Resource Division (BRD) should fill the data gaps.

The California Department of Fish and Game (CDFG) is actively participating with the US Fish and Wildlife Service (USFWS) to work toward the recovery of the Modoc sucker (Catostomus microps) in the upper Pit River drainage of northern California. Cooperative projects include the collection of genetic samples (to study the potential hybridization and the systematic status of Pit sucker populations), fish surveys, and development of habitat/fish passage projects.

On April 12, 2000, the USFWS listed the Santa Ana sucker (Catostomus santaanae) as threatened throughout its native historic range in the Los Angeles, San Gabriel, and Santa Ana Rivers. Santa Ana suckers have lost approximately 75% of their historic range, largely due to urbanization of the Los Angeles metropolitan area. Survey efforts for the Santa Ana suckers this year suggest that populations are stable and that the species is recruiting throughout most of its restricted current range. CDFG biologists found many Santa Ana suckers in a section of the North Fork San Gabriel River which is heavily used as an Off Highway Vehicle area in the Angeles National Forest. The National Forest Service (NFS) and CDFG plan to conduct additional studies on this section of river as funding allows. The CDFG has contracted a life history study of the Santa Ana sucker and the Santa Ana speckled dace (Rhinicthys osculus ssp.) in the East Fork San Gabriel River.

The black toad (Bufo exsul) populations in Deep Springs Valley remain stable. Although the threat of more in-valley grazing looms. This is due to the continued push to move cattle grazing from high elevation allotments.

Some previously-designated "stronghold" populations of mountain yellow-legged frog (Rana muscosa), Yosemite toad (Bufo canorus) and, potentially, western toads (Bufo boreas) in the eastern Sierras have been diagnosed with Chytrid fungus.

An application to obtain grass carp (Ctenopharyngodon idella) for golf course ponds in the Mammoth Lakes area has brought to the forefront the looming threat that existing State policies are inadequate to prevent the introduction of new species. There is currently an "understanding" within CDFG that no grass carp applications for Inyo and Mono counties will be granted. However, this policy needs to be clarified and formalized in the CDFG Operations Manual.

Contractors working for the Death Valley National Park (DVNP) are in their second year of a study to evaluate the effects of water diversion activities on aquatic invertebrates. Preliminary finding for the study should be available next year.

DVNP staff and BRD personnel have been conducting amphibian research studies in Darwin Falls area of the park. The site is the only location in the park with a naturally occurring population of western toads. A study was designed to look at toad microhabitat preferences. The study found that the presence of western toads at a given site was significantly correlated with the presence of surface water. This finding suggests that anthropogenic water diversions will reduce the quantity of habitat that may be available for the species.

DVNP staff continues to oversee the implementation of the Devils Hole bioenergetics/community relationships research study. The study has been funded by the BRD. Study participants include the National Park Service, USFWS, Nevada Division of Wildlife, Northern Arizona University, and the Sierra Nevada Aquatic Research Lab. The study has, in part, been designed to identify the causal factors that are responsible for reducing the number of Devils Hole pupfish (Cyprinodon diabolis) over the past four or five years. Project staff completed their first year of the study in August 2000.

Devils Hole pupfish numbers have continued to decline during the past four or five years. Only 286 fish were observed during an August 2000 census, as compared to an average of 522 fish during fall counts from 1988 through 1995. Several National Park Service activities have been undertaken to enhance the protection of the fish, including the installation of electronic security equipment at the site; initiation of comprehensive water chemistry analyses; and moving the parking area away from Devils Hole.

Desert pupfish (Cyprinodon macularius) continue to thrive in San Felipe Creek, although some mosquitofish (Gambusia affinis) and sailfin mollies (Poecilia latipinna) also inhabit the creek. An intermittent lower portion of the creek has prevented Tilapia from entering and moving upstream. Desert pupfish still inhabit lower Salt Creek, Riverside County, although the population has been extirpated from an upper section.

Desert pupfish are thriving at most refuge sites. Pupfish are doing particularly well at the Oasis Springs Ecological Reserve refuge ponds. The desert pupfish population there has tripled since the new well was constructed in 1999. The additional water has resulted in significant additional habitat at the terminus of the ponds/creek. At the Dos Palmas desert pupfish refuge, CDFG is working with Bureau of Land Management (BLM) planning the removal of largemouth bass from a pond (which does not contain pupfish). The agencies are planning to add additional refuge ponds at Dos Palmas.

CDFG is using Section 6 funds to pay for habitat restoration on Salt Creek. In fall/early winter CDFG will begin an extensive salt cedar (Tamarix spp.) removal project at the upper Salt Creek. BLM and the California Department of Forestry will be assisting with this project After the restoration is completed, the CDFG plans to reestablish pupfish in upper Salt Creek. The BLM has removed some salt cedar from Harper's Well Wash at San Felipe Creek. The CDFG and BLM plan to undertake additional salt cedar removal project as funding allows.

Two future projects, the Salton Sea Restoration Project (SSRP) and the Imperial Irrigation District-San Diego County Water Transfer could have profound long term effects on the Salton Sea. Both projects could potentially limit desert pupfish movement and increase the vulnerability of resident pupfish populations to contaminants or poor water quality conditions. The USFWS and CDFG are cooperating with the Bureau of Reclamation (BOR) and Salton Sea Authority by providing recommendations for needed research and to incorporate recovery strategies for the desert pupfish into the SSRP. USFWS and CDFG are also seeking remedies to offset potential impacts associated with the Imperial Irrigation District-San Diego County Water Transfer. This water transfer could result in a reduction of inflows to the Salton Sea of up to 500,000 acre feet per year. This transfer could reduce the water in the irrigation drains and shoreline pools at the southern end of the Sea which provides habitat for the pupfish. The USFWS has received funding to investigate selenium contamination in drains and shoreline pools at the Salton Sea and its potential effect on resident pupfish populations.

11:15:00 AM 11/16/00 - Lower Colorado River area report - Stefferud, J^*1; Bettaso, R²; Minckley, C³; Stefferud, S⁴; Clarkson, R⁵; Tibbitts, T⁶; Myers, T⁷; Rinne, J⁸  (1 USDA Forest Service, Tonto National Forest; 2 Arizona Game and Fish Department, Nongame Branch; 3 U.S. Fish and Wildlife Service, Arizona Fisheries Resource Office; 4 U.S. Fish and Wildlife Service, Arizona Ecological Services Field Office; 5 Bureau of Reclamation, Phoenix Area Office; 6 National Park Service, Organ Pipe Cactus National Monument; 7 USDA Forest Service, Apache-Sitgreaves national forests; 8 USDA Forest Service, Rocky Mountain Research Station)

Researchers and managers concerned with native fisheries in the lower Colorado River basin in Arizona (including Little Colorado River, Virgin River, Bill Williams River, and Gila River) were contacted to provide brief summaries of their activities on native fishes during the past year. Following is a summary of their responses.

GILA TROUT - Oncorhynchus gilae - Arizona Game and Fish Department (AZGFD): AZGFD stocked Dude Creek in the Verde River drainage on three separate occasions during the past year with ca. 160 mixed age-class fish originating from Spruce Creek in New Mexico. Introduction of Gila trout into Raspberry Creek in Blue River drainage is planned for fall 2000. Arizona Ecological Services Office (AZESO):  Gila trout introduction into Raspberry Creek is part of a larger multi-agency effort to restore native fish in the Blue River. Other actions include design work now underway for a fish barrier near the mouth of the Blue River and negotiations to obtain an easement to discontinue the private trout hatchery in the upper Blue River, return those flows to the river, and restore the riparian area. The Nature Conservancy is assisting in the easement effort. An environmental history of the Blue River is being funded by the Apache-Sitgreaves National Forest to provide a basis for restoration plans.

APACHE TROUT - Oncorhynchus gilae apache - Arizona Fisheries Resources Office (AZFRO)-Pinetop: Sections of two streams were renovated on the Fort Apache Indian Reservation for Apache trout. Population surveys are underway for all Apache trout populations. Repairs to the gabion barriers on Paradise and Ord creeks were conducted. AZGFD:  Apache trout are reared at the AZGFD's Silver Creek Hatchery and are stocked by AZGFD personnel into streams in the White Mountains. The federal hatcheries at Williams Creek and Alchesay continued to produce and rear Apache trout for stocking into streams in the White Mountains as well as supplying AZGFD with Apache trout for Silver Creek Hatchery. An updated Draft Revised Recovery Plan (now called the Recovery Implementation Plan) is ready to go out to USFWS in several weeks for review and official sanction.

BONYTAIL - Gila elegans - AZGFD, AZFRO-Parker: In spring 2000, >500 bonytail (250-500 mm) from Willow Beach National Fish Hatchery were stocked into Lake Mohave. No bonytail were stocked into Lake Havasu. Fourteen bonytail were reared at Davis Cove, a grow-out pond in Lake Mohave. From July 1999 to February 2000, >600 pounds of crayfish were removed from Davis Cove. Captured one bonytail during razorback sucker sampling efforts at Lake Havasu.

HEADWATER CHUB - Gila nigra - National Forest System (NFS)-Tonto: As a result of settlement negotiations with several environmental organizations (including American Rivers, Center for Biological Diversity, Arizona Riparian Council, Sierra Club, and others), and state and Federal agencies, Arizona Public Service Company has agreed to surrender their license to operate the Childs/Irving Hydroelectric Facility on Fossil Creek, effective December 31, 2004. After flows are returned, most of the facilities and impacts of the project will be removed or returned to a natural state. Bureau of Reclamation (BR)-Phoenix: Engineering analyses and construction plans for fish barriers in Fossil Creek are being developed.

ROUNDTAIL CHUB - Gila robusta - AZGFD: A status survey for roundtail chub Gila robusta and headwater chub in the lower Colorado basin is being conducted with funding from the 1994 CAP opinion. The purpose of this survey is to facilitate a listing decision. To date, queries have been conducted of 18 museums in North America and Europe, resulting in a comprehensive listing of museum collections of the species in the lower Colorado River basin. Knowledgeable biologists have been contacted for additional information regarding the biology, distribution, and current status of roundtail chub. Gaps in knowledge have been identified, collection records reviewed, and 22 streams identified as high priority for sampling. Surveys have been initiated and are approximately 45% completed. A draft interim report has been submitted to FWS, reviewing and summarizing pertinent literature about the biology, ecology, life history, habitat, distribution, and taxonomy of roundtail chub. A comprehensive bibliography of published and gray literature pertaining to roundtail chub in the lower Colorado River Basin is included. The interim report includes summaries of land and water uses for most drainages.

GILA CHUB - Gila intermedia - AZGFD, NFS-Coronado: Sabino Canyon northeast of Tucson was renovated to remove nonnative green sunfish Lepomis cyanellus and western mosquitofish Gambusia affinus. Gila chub are present higher in the drainage and have begun to naturally recolonize the renovated waters. NFS-Coronado: Plans are ongoing to modify into barriers two bridges on the Forest downstream of the main barrier to discourage upstream reinvasion of the nonnative fishes.  NFS-Prescott: Surveys confirmed presence of Gila chub in Indian Creek. AZESO: A listing package has been prepared for Gila chub and is under review. Priority for processing this package may be low because it is not under lawsuit, so it is likely that a proposed rule will not be published for at least a year.

YAQUI CHUB - Gila purpurea - AZESO: The El Coronado Ranch Habitat Conservation Plan is being implemented. The monitoring plan should be completed by October 1.

SONORA CHUB - Gila ditaenia - NFS-Coronado: Formal consultation with AZESO on grazing activities affecting Sonora chub are ongoing. The allotment includes California Gulch, an intermittent stream where Sonora chub was found in 1995. Changes in management have the goal of reducing cattle impact on the riparian area so extent of surface water in California Gulch would be increased both in time and space, allowing more permanent occupation by Sonora chub in the US in this stream. A bridge has been constructed at the Ruby Road crossing of Sycamore Creek.

LITTLE COLORADO SPINEDACE - Lepidomeda vittata - AZGFD: LC spinedace populations at the Flagstaff Arboretum pond were monitored in October, April, May and June using minnow traps. 181 LC spinedace were recorded (<150 mm) and released back into the pond. LC spinedace were collected from Leonard Canyon for use as broodstock for the refugium at Flagstaff Arboretum pond. On April, 2000, spinedace from the Flagstaff Arboretum Pond were stocked into Houston Draw (50 fish) and General Springs (31 fish). NFS-Coconino: Streams within critical habitat of LC spinedace were surveyed for riparian and habitat condition.

VIRGIN RIVER SPINEDACE - Lepidomeda m. mollispinis - AZGFD: Monitoring actions for Virgin River fishes were completed at Beaver Dam Wash, Mormon Well, and upstream from the confluence with Virgin River. The Mormon Well site, located just south of the Utah-Arizona border, has proved to be a reliable site (when water is present) for finding large numbers of spinedace along with speckled dace Rhinichthys osculus and desert sucker Pantosteus clarki. No exotic fishes have been sampled here. Spinedace are in all types of habitats ranging from pools and runs with undercut banks to small shallow riffles with no apparent cover or shading. Most are YOY and Age-1, but a few large (140 mm) individuals are present. The site is dry periodically. The site at the confluence appears to have much better spinedace habitat than the Mormon Well site but, so far, no spinedace have been found. Large numbers of speckled dace, desert sucker, and red shiner Cyprinella lutrensis are in the reach.

SPIKEDACE - Meda fulgida - NFS-Rocky Mountain Station: Annual monitoring of the fish assemblage in upper Verde River was conducted, no spikedace were found this year. Spikedace have not been found during this effort since 1996, although one individual was taken by AZGFD sampling in 1999. Research on effects on native fishes of removal of nonnative predators is ongoing in the upper Verde River. NFS_Prescott: Consultation with FWS is ongoing on 'Chino-4' allotments that encompass much of the upper Verde River. Livestock have been restricted from accessing the river along about 30 miles of stream. AZESO: Critical habitat was designated for 898 miles of stream in Arizona and New Mexico for spikedace and loach minnow. No lawsuits have yet been filed to overturn that designation, so the 17-year effort to get critical habitat for those two species may have finally succeeded.

LOACH MINNOW - Tiaroga cobitis - AZFRO-Pinetop: A management plan for loach minnow for the Fort Apache Indian Reservation was drafted by the Tribe with the cooperation from AZFRO-Pinetop. The Plan was signed by the Tribe and approved by USFWS early this spring. This document will assist the Tribe in managing the loach minnow within reservation boundaries. The White Mountain Apache Tribe conducted population surveys for loach minnow in the East Fork of the White River, Fort Apache Indian Reservation. In addition surveys for loach minnow were conducted in the White River and Canyon Creek on the Fort Apache Indian Reservation. NFS-Apache-Sitgreaves, BR-Phoenix: BR is conducting engineering studies for installation of fish barrier on Blue River.

RAZORBACK SUCKER - Xyrauchen texanus - AZGFD, Arizona State University (ASU), Bureau of Land Management (BLM), AZFRO-Parker: Annual razorback sucker roundup at Lake Mohave. 593 razorbacks were sampled. AZFRO-Parker: First roundup for razorback suckers on Lake Havasu where 38 razorbacks and one bonytail were taken. All were repratriates except for one razorback. AZGFD: Grow-out of razorback suckers continued at the AZGFD Bubbling Ponds Hatchery. Razorback suckers averaging 10 inches TL were stocked from Bubbling Ponds into Lake Mohave, Lake Havasu, Colorado River in Parker Strip, and Verde River near Childs. In addition, 90 large (avg. 450mm) razorback suckers and 14 bonytail, were reared at Davis Cove, a grow-out pond in Lake Mohave. Sampling of the Verde River to monitor reintroduced Colorado pikeminnow Ptychocheilus lucius and razorback suckers was conducted. Between Beasley Flat and Childs seven razorbacks were caught. All were in generally good health, with little parasite loading. No pikeminnow were caught. Natives fishes made up 26% of the electrofishing catch. During investigations of the fisheries in Fossil Creek drainage, 2 razorback suckers were captured in Stehr Lake, a small regulating reservoir in the project. They were probably survivors of fish stocked there in the 1980's.

DESERT PUPFISH - Cyprinodon macularius - AZFRO-Parker: Refugia for desert pupfish on Cibola and Imperial national refuges were established and stocked. Fish were from the stock established from El Doctor in Sonora, MX. AZESO: A highway flood-water retention basin in Tempe is currently proposed for stocking under a Safe Harbor agreement with Gila topminnow and desert pupfish. The Safe Harbor agreement provides for actions that promote conservation and recovery of the species by providing refugia sites, while allowing the landowner flexibility to remove species and habitat to baseline conditions if they desire. The agreement has stipulations for monitoring of populations and habitats and function of the agreement and provides for funding both the mitigation and monitoring provisions. An additional benefit from the action will be control of mosquitoes Hummus pestis. The permit for take of individuals under this agreement should be signed by September 30. Other sites owned by the Arizona Department of Transportation may be used as additional refugia sites for either species. AZGFD: Three reintroduced populations of desert pupfish were monitored. Finley Tank supported pupfish of questionable heritage, and desert pupfish were absent from AD Wash and Hidden Water Spring.

QUITOBAQUITO PUPFISH - Cypdrinodon eremus - AZFRO-Parker: Began work with the Pinacate Biosphere preserve to reestablish a native riparian zone along the Sonoyta River to benefit Quitobaquito pupfish. National Park Service-Organ Pipe Cactus National Monument: Have been developing sampling methodologies with ASU to assist in management and monitoring of status of population, and with NFS-Tonto to provide method for early detection of nonnative fishes. Are proposing to build supplemental holding facility at Park headquarters that would also serve for public education.

GILA TOPMINNOW - Poeciliopsis occidentalis - AZFRO-San Carlos: In spring 2000, began work on the renovation of the third and final spring in the Bylas Springs Complex, S1. Following barrier modifications and the removal of introduced riparian vegetation the spring was successfully renovated with the cooperation of the San Carlos Apache Tribe, AZGFD, Bureau of Indian Affairs, Environmental Protection Agfency, and AZESO. Gila topminnow from the original S1 stock are scheduled to be released into S1 in the fall of 2000. Springs S2 and S3 were successfully renovated and restocked in 1996 and 1998, respectively. NFS-Coronado: Last year's consultation with FWS on grazing allotments resulted in mangement changes on allotments in the Redrock Canyon drainage, where Gila topminnow are present. One existing exclosure was extended, and another was built to enhance riparian and aquatic conditions for the species. Annual monitoring of Gila topminnow and western mosquitofish in Redrock Canyon shows a generally downward trend in relative abundance of topminnow over the past 11 years with topminnow last year (October '99) comprising 47% of the total catch. BLM: In September, Gila topminnow were stocked into Lousy Canyon in the Agua Fria drainage. This stream is already the site of a restoration stocking of Gila chub. This is the first new Gila topminnow population started in the wild since 1993. AZGFD: Acute tolerances of Gila topminnow and western mosquitofish to ammonia and high water temperature as well as their use of simulated emergent vegetation were determined in order to evaluate each species' potential to effectively control mosquito larvae in constructed wetland habitats. Fifteen localities were monitored for presence of natural Gila topminnow populations. Only ten of the locations continue to support topminnow. They were Bylas Spring, Middle (or 'MZ') Spring, Salt Creek, Redrock Canyon below Cott Tank, Sonoita Creek below Patagonia Lake Dam, Monkey Spring, Fresno Canyon, Cottonwood Spring, Santa Cruz River (at Chavez Siding and Santa Gertrudis roads), and a tributary to Sonoita Creek east of Fresno Canyon. No topminnows were collected from Sheehy Spring, Santa Cruz River above Mexico Border, Sonoita Creek through the TNC Preserve, and most notably, none were collected from Redrock Canyon at the Falls or from Sharp Spring. Nine monitoring events were conducted at localities supporting reintroduced Gila topminnow populations. Kayler Spring failed to produce Gila topminnow for the second time in eight years. Two captive populations of Gila topminnow and desert pupfish were also surveyed. The Hassayampa River Preserve no longer supports Gila topminnow or desert pupfish, but Acacia Elementary School does support a small topminnow population. AZGFD, AZESO: The draft revised Gila topminnow recovery plan is in the final stages of approval.

GENERAL - NFS-Apache Sitgreaves: A study was funded to survey and collect specimens of California floater Anodonta californiensis in historical locations across its range in the western United States. Dr. Walter (Randy) Hoeh from Kent State is now preparing report. Preparing conservation agreement for 3 Forks springsnail Pyrgulopsis trivialis with FWS. The Nature Conservancy-Arizona: Purchased Sierra Blanca property within NFS-Apache Sitgreaves on Boneyard Creek, which flows into EF Black River. Will facilitate recovery efforts for several aquatic species, including loach minnow, leopard frog Rana sp., and 3 Forks springsnail. AZFRO-Parker:  Transferred the Achii Hanyo native fish facility to the control of Willow Beach National Fish Hatchery. Presented several talks on the problem of giant salvinia Salvinia molesta in the lower Colorado River. AZFRO-Pinetop: Native fish surveys were conducted in upper Canyon Creek and at selected sites on the Salt River from the Highway 60 bridge to the Fort Apache Indian Reservation boundary. Plans are to survey the lower reach of Canyon Creek to the confluence of the Salt River this fall. San Bernardino/Leslie Canyon NWR: In 1995 the Asian tapeworm Bothriocephalus acheilognathi was found in the fishes of the San Bernardino/Leslie Canyon NWR. These areas were surveyed again this summer to provide an information update on the occurrence of Asian tapeworms in fishes on the Refuge. Annual summer fish counts were also conducted from June through September 2000. NFS-Tonto: Drought in central Arizona has caused the removal or reduction of livestock from most of the low desert allotments on the Forest. At this time, livestock will not be returned to the allotments until resource conditions improve to a point where livestock impact can be tolerated, and NEPA analysis for allotment management plans completed. AZESO, BR-Phoenix: Implementation of the reasonable and prudent alternatives contained in the 1994 biological opinion on impacts of Central Arizona Project fish transfers to the Gila River basin continues. Implementation will be discussed in two papers at this meeting and concerns primarily spikedace, loach minnow, Gila topminnow, and razorback sucker. An additional draft jeopardy biological opinion on nonnatives and the CAP in the Santa Cruz subbasin and effects to Gila topminnow was issued last summer, using the same approach as the 1994 opinion. A final opinion on the Santa Cruz is still in preparation. BR-Phoenix: A $2.7M contract to construct fish barriers on Aravaipa Creek has been awarded and construction should be completed before Christmas. Plans for similar fish barriers on San Pedro and Santa Cruz rivers are progressing. A comprehensive statistical power analysis of Reclamation's long-term monitoring program to detect non-native fish invasions was recently completed, and monitoring protocol are being adjusted accordingly. The fourth annual transfer of $500K to Fish and Wildlife Service for native fish conservation and non-native fish eradication projects was finalized. BR-Phoenix has been involved with funding of several native fish research projects, and has undertaken engineering analyses of various other fish barrier and artificial stream construction projects. A 5-year information and education program that addresses the problems non-native fishes create for native fishes and their habitats has been initiated.

11:30:00 AM 11/16/00 - Study and conservation of native fishes in the northwest region of Mexico: overview 2000 - Varela-Romero, A^*1; Davila-Paulin, JA²; Minckley, CO³; Najera, SN⁴; Campoy-Favela, JR⁵; Garcia-Hernandez, J⁶; Yruretagoyena, C⁷; Ellis, ME⁸  (1 DICTUS, Universidad de Sonora, Hermosillo, Sonora.; 2 Reserva de la Biosfera Gran Desierto de Altar y el Pinacate SEMARNAP, El Pinacate, Son.; 3 Arizona Fisheries Resources Office, US Fish and Wildlife Service, Park, AZ.; 4 US National Park Service, Las Cruces, NM.; 5 Reserva de la Biosfera Alto Golfo de California y Delta del Río Colorado SEMARNAP, San Luis R.C./Instituto del Medio Ambiente y Desarrollo Sustentable de Sonora (IMADES), Estación de Campo Golfo de Santa Clara, San Luis R.C., Son.; 6 Deptartment of Soil Water and Environmental Science, University of Arizona, Tucson, AZ.; 7 Centro Regional de Estudios Ambientales, A.C. (CREAS), Mexicali, B.C.; 8 Imperial National Wildlife Refuge, U.S. Fish and Wildlife Service, Martínez Lake, AZ.)

The northwestern region of Mexico are crossing by an intensive drought that affects directly to the native fish. The mayor reservoirs in Sonora, Sinaloa, and in smaller proportion in Chihuahua, retain minimal water volumes and the natural riverbeds are not the exception. The study, conservation and management of the native fish is made difficult in such desertic area. The efforts gathered in this abstract are the most relevant registered a long of the year.

The Recovery and Management Project of the Desert pupfish ({Cyprinodon eremus}) in the Rio Sonoyta within the Gran Desierto de Altar y El Pinacate Biosphere Reserve maintains as principal objective the protection of the desert pupfish desert and their habitat through the management and restoration of a portion of the Rio Sonoyta. Until the moment, activities have been concentrated in recovering the riparian habitat in a segment of the river through the elimination of the salt pine ({Tamarix ramossisima}) and to protect this river segment where the desert pupfish was found permanently. The Funds for this project for the most part originates of the USFWS.

Additionally, and as support to this project, it has been proposed the creation of a stock population of {C.eremus} within the Rio Sonoita Basin in facilities of the Puerto Peñasco Experimental Unit of DICTUS, without assured funds until the moment.

The Project Binacional Cooperative Effort for the Conservation of the Desert Pupfish ({Cyprinodon macularius}) in the Alto Golfo de California y Delta del R|i|o Colorado Biosphere reserve, M|e|xico, include efforts developed from 1998 in relationship to the systematical evaluation and conservation of the desert pupfish populations ({C. macularius}) in several sites within the Resere. The activities include evaluation collections in the zones of wetlands where the species inhabits  such as the El Doctor Ci|e|negas (several sites) and in two sites in the margins of the Ci|e|nega de Santa Clara (adjacent lagoons to the Wellton-Mohawk Channel and the area of the Ejido La Flor del Desierto). 5 fenced zones (of different surfaces) have been created in the locality of El Doctor to favor the expansion of the wetlands, recover the vegetation and to restore shallow zones for the species. It has been collaborated with several efforts of diffusion and local environmental education on this species and the status through a permanent exhibition within Information Center of the Estaci|o|n de Campo del Golfo de Santa Clara, guided visits with teachers and students and the cooperation of members of ejidos surrounding the wetlands. From the evaluation samplings we have detected a sensibly reduction of the  population found in the Wellton-Mohawk Channel adjacent lagoons has, while in the rest of the sites are found relatively abundant. It was registered a new population in the locality known as La Pila, in which was transferred to a tank for reproduction. Currently it is worked in the allusive signs placement to the species conservation, the impression of a diffusion booklet, a curricular on the species for teachers and the installation of a permanent exhibition on the species in the Museum of the Geot|e|rmica Cerro Prieto. This effort is supported by the U.S. Fish and Wildlife Service, North American Wetland Conservation Council, Comisi|o|n Nacional de AreasNaturales Protegicas/SEMARNAP and the International Alliance of the Desert Sonorense (ISDA).

The Project Concentration of selenium (Se) in Desert Pupfish (|Cyprinodon macularius|) collected from the Colorado River delta wetlands, Mexico, have as objective to determine the levels of selenium in the endangered Desert Pupfish found in the Colorado River delta wetlands where high levels of selenium have been detected in sediments. Selenium is a naturally occurring element that originates from Cretaceous formations upstream the Colorado River. These areas are continuously being eroded and dissolved selenium concentrations can be found along the river until it reaches the Gulf of California. High levels of selenium have been found in backwaters of the River, although no effects on wildlife have been recorded. Selenium is a nutrient but it is also a toxic element if consumed at higher concentrations. It can cause reproductive failure, embryonic abnormalities and death in wildlife. During July 2000, a field collection at three sites in the delta was conducted. All fish were collected using traps. In sites where other species were trapped, they were also analyzed. The three sites visited were The El Doctor pozos, La Flor del Desierto, and the Geothermal evaporation lagoons. As Conclusions, levels of selenium in desert pupfish and sailfin molly exceeded the threshold for potential reproductive impairment for sensitive species. However, there are no signs of abnormal development or reproductive failure. It is possible that the threshold for native fishes is higher than for non-natives, due to the historic presence of selenium in the Colorado River waters.

La región del Noroeste de México se encuentran atravesando por una intensa sequía que afecta directamente a los peces nativos. La mayor parte de las presas en Sonora, Sinaloa y en menor proporción en Chihuahua retienen mínimos volúmenes de aguas y los cauces naturales no son la excepción. El estudio, conservación y manejo de los peces nativos se hace diffcil en un ámbito desértico. Los esfuerzos recopilados en este resumen son los mas relevantes registrados a lo largo del año.

El Proyecto de Recuperación y Manejo del pez cachorrito del Desierto (Cyprinodon eremus) en el Río Sonoyta dentro de la Reserva de la Biosfera El Pinacate y Gran Desierto de Altar mantiene como objetivo principal la protección del pez cachorrito del desierto y su habitat mediante el manejo y restauración de una porción del Río Sonoyta. Hasta el momento las actividades se han concentrado en recuperar el habitat ribereño en un segmento del río mediante la eliminación del pino salado (Tamarix ramossisima) y proteger éste segmento de río donde se encuentra permanentemente el pez cachorrito. El financiamiento para éste proyecto en su mayoría proviene del USFWS. Adicionalmente y como apoyo a éste proyecto, se ha propuesto la creación de una población de resguardo de C.eremus dentro de la Cuenca del Río Sonoyta en instalaciones de la Unidad Experimental Puerto Peñasco del DICTUS sin que hasta el momento se recaude un financiamiento asegurado.

El Proyecto Esfuerzo Cooperativo Binacional para la Conservación del Pez Cachorrito del Desierto (Cyprinodon macularius) en la Reserva de la Biosfera Alto Golfo de California y Delta del Río Colorado, México, comprende esfuerzos desarrollados desde 1998 en relación a la evaluación sistemática y conservación de las poblaciones del pez cachorrito del desierto (Cyprinodon macularius) en varios sitios dentro de la Reserva. Las actividades incluyen colectas de evaluación en las zonas de humedales donde habita la especie como las Ciénegas El Doctor (varios sitios) y en dos sitios en los márgenes de la Ciénega de Santa Clara (lagunas adyacentes al Canal Wellton-Mohawk y el área del Ejido Flor del Desierto). En la localidad de El Doctor se han cercado 5 zonas (de diferentes superficies) para favorecer la expansión de los humedales, recuperar la vegetación y restaurar zonas someras para la especie. Se ha colaborado con diversos esfuerzos de difusión y educación ambiental local sobre esta especie y su situación mediante una exhibición permanente dentro del Centro de Información de la Estación de Campo Golfo de Santa Clara, visitas guiadas con maestros y alumnos y la cooperación de miembros de ejidos aledaños a los humedales. De los muestreos de evaluación hemos detectado que la población encontrada en las lagunas adyacentes al Canal Wellton-Mohawk ha disminuido sensiblemente, mientras que en el resto de los sitios se encuentran relativamente abundantes. Se registró una nueva población en la localidad conocida como La Pila en donde se transfirió a un estanque para su reproducción. Actualmente se labora en la colocación de letreros alusivos a la especie y su conservación, la impresión de un folleto divulgativo, una curricula sobre la especie para maestros y la instalación de una exhibición permanente sobre la especie en el Museo del Campo Geotérmico Cerro Prieto. Este esfuerzo es apoyado por el U.S. Fish and Wildlife Service, North American Wetland Conservation Council, Comisión Nacional de Areas Naturales Protegidas/SEMARNAP y la Alianza Internacional del Desierto Sonorense (ISDA).

El proyecto Concentración de Selenio (Se) en el Pez Cachorrito del Desierto (Cyprinodon macularius) colectados en humedales del Delta del Río Colorado, México, tiene como objetivo determinar los niveles de selenio en el pez cachorrito del desierto en peligro de extinción en humedales del Delta del Río Colorado, donde se han detectado niveles altos de selenio en los sedimentos. El selenio es un elemento que naturalmente ocurre y se ha originado de formaciones Cretácicas río arriba del la Cuenca del Río Colorado. Estas áreas son continuamente erosionadas y las concentraciones de selenio disueltas se pueden encontrarse a lo largo del río hasta su desembocadura en el Golfo de California. Altos niveles de selenio se han encontrado en remansos del Río, aunque no se hayan registrado efectos sobre la fauna silvestre. El selenio es un alimento pero es también un elemento tóxico si se consume a elevadas concentraciones. Puede ocasionar falla reproductiva, anormalidades embrionarias y muerte en la fauna silvestre. Se realizaron colectas de campo en tres sitios del delta durante Julio del 2000. Todos los peces se colectaron usando trampas. En los sitios donde otras especies se atraparon, también fueron analizados. Los tres de sitios visitados fueron pozos El Doctor, La Flor del Desierto y las lagunas de evaporación de la Geotérmica de Cerro Prieto. Como conclusiones se encontró que los niveles de selenio en el pez cachorrito del desierto y molly de vela excedieron el umbral del deterioro del potencial reproductivo para especies sensibles. Sin embargo, no hay señales de desarrollo anormal o fracaso reproductivo. Es posible que el umbral para peces nativos sea más alto que para los nonativos debido a la presencia histórica del selenio en aguas del Río Colorado.

11:45:00 AM 11/16/00 - Northeast Mexico coordinator's report - Contreras-Balderas, S^*1  (1 Bioconservación A.C., Monterrey, N.L., México)

The drought is continuing in the region, although there are hopes that the hurricane season will bring enough rains to supply basic needs, but in general we keep with the water deficit. The Río San Juan sub-basin is at an all time low, below 2% its virgin runoff. Native fishes are suffering from this condition, and several species have become more scarce. The list of introduced fishes of Mexico continues to expand, with 8 recent additions in the San Juan sub-basin. The Río Salado, Río Alamo, and Río Conchos have not been surveyed recently. In the Casas Grandes complex, we found 2 pupfishes, 1 new and 1 possibly new, the second was observed on a vacation, and was gone when the locality was latter visited to take samples. In the Cuatro Ciénegas sub-basin, the UANL group is continuing its efforts to control the exotic African jewel fish (Hemichromis), tilapia, and water hyacinth. Only the last has been succesfully controlled, and Lourdes Lozano will report on this. The African jewel fish is expanding, and the aquarium screw snail reported by Alberto Contreras is now almost everywhere. On the positive side, the Federal Government has compiled the proposal of the Carta Nacional Pesquera, a report containing all basic information on endemic and exotic fishes in each of 10 regions, and it is supposed to regulate fisheries and aquaculture. It contains definitions, advises on legal uses and exploitation, threats to resources, and especially the recommendation to not introduce more aquatic species and control pollution. It has not received final approval, but at least the top national level has received a message. If the recommendations appear in the final report, they will become the regulatory body for fisheries and aquaculture. We should commend the Dirección General de Investigation en Acuacultura, SEMARNAP, for its compilation. The final version of the WWF report on the conservation priorities of the Chihuahuan Desert is ready to go to the printer. Another interesting book just out of the press is R. Claudi & J.H. Leach, 2000, Nonindigenous Freshwater Organisms, Vectors, Biology, and Impacts; Lewis Publishers. On November 9-11, 2000, the ONG meeting Uniendo la Cuenca was held, organized by the Coalition for Sustainable Development of the Río Grande/Río Bravo Basin, details later.

02:00:00 PM 11/16/00 - Using GIS and GPS to map the seasonal distribution and relative density of Independence Valley speckled dace and Independence Valley tui chub - Rissler, PH^*1; Scoppettone, GG¹; Shea, SS¹; Byers, S²  (1 USGS, BRD, Western Fisheries Research Center, Reno Field Station; 2 USFWS, Nevada Fish and Wildlife Office)

The Independence Valley speckled dace, Rhinichthys osculus lethoporus, and Independence Valley tui chub, Gila bicolor isolata, are endemic to Warm Springs Marsh, south-central Elko County, Nevada, USA. Warm Springs Marsh also harbors non-indigenous and predaceous largemouth bass, Micropterus salmoides, and bluegill, Lepomis macrochirus. The decline of the speckled dace and tui chub has been attributed to their limited distribution, habitat disturbances, and introduction of non-native fishes. Previous fish surveys in the area focused on the marsh’s water sources; several warm water springheads, and virtually ignored the 300 ha marsh itself. To institute a systemic sampling survey, Global Positioning System (GPS) and Geographic Information System (GIS) were employed. We used GIS to produce a 75 m sampling grid from a 1:100,000 scale hydrologic coverage of the marsh. The resulting grid produced 669 potential sampling points. The UTM (Universal Transverse Mercator)zone 11, NAD27 (North American Datum 1927) coordinates for the sampling grid were then downloaded into Precision Lightweight GPS Receivers (PLGR) to enable navigation to and from the sampling sites. Standard minnow traps were used as the capture method. The distribution of speckled dace and tui chub were highly affected by the occurrence of largemouth bass. Dace and chub were rare in areas where bass occurred. Dace were captured thoughout the marsh outside of bass occurrence while chub distribution was more patchy. Seasonally, captures of dace were highest in the spring followed by fall then summer while chub captures were highest in spring followed by summer and fall. This information will be used by resource managers to develop management guidelines for the recovery of these two species.

02:15:00 PM 11/16/00 - Flow variation and proposed management to enhance Colorado pikeminnow and razorback sucker in the Green River subbasin - Modde, T^*1  (1 U.S. Fish and Wildlife Service)

Following construction of mainstem dams, abundance and distribution of Colorado pikeminnow, {Ptychocheilus lucius}, and razorback sucker, {Xyrauchen texanus}, declined throughout the Colorado River Basin. Demise of native fishes resulted from lack of recruitment caused several factors including alteration of the natural hydrograph and predation from introduction of nonnative fishes into the altered habitats. The largest populations of Colorado pikeminnow and razorback sucker remaining in riverine habitats of the Colorado River Drainage are found in the Green River subbasin, of which a few tributaries still contribute natural flow magnitudes during the spring run-off.

Despite the presence of natural flows in several tributaries, the hydrograph of the middle Green River is heavily influenced by the operation of Flaming Gorge Dam. Since it construction in 1962, the magnitude and duration of spring flood flows have dramatically declined. The initial operating regime of the dam facilitated peaking power throughout the year and eliminated variability in seasonal flow rates. Reduction in discharge magnitude modified the geomorphic structure of the channel and reduced connectivity of the river to the floodplain. In addition, floodplain nursery habitat for razorback sucker was greatly reduced and main-channel backwater nursery habitat for Colorado pikeminnow was inundated during the summer months.

An increase in recruitment of Colorado pikeminnow in the middle Green River occurred following high flood flows in 1983-4 and re-operation of Flaming Gorge in 1988. The reduction of base flows of the dam increased the surface area of backwaters, increasing juvenile pikeminnow nursery habitat. Following re-operation of Flaming Gorge Dam releases, annual survey counts of adult Colorado pikeminnow have more than doubled. On the contrary, the numbers of razorback sucker remain depressed. Although base flows have increased pikeminnow nursery habitat, the magnitude of spring flows remained constrained from Flaming Gorge Dam such that re-operation flows are still much less than historical magnitude and duration. Thus, little floodplain habitat is available to drifting razorback sucker larvae. Although different habitat requirements are needed for both Colorado pikeminnow and razorback sucker, the flow variability is necessary to produce the geomorphic characteristics needed for recruitment of both species. Management is necessary to provide high spring flows that benefit recruitment of razorback sucker in high flow years, yet provide the geomorphic channel structure that enhances Colorado pikeminnow nursery habitat in subsequent lower flow years.

02:30:00 PM 11/16/00 - A new tool for an old problem: microsatellite DNA and polymorphism of Cichlasoma minckleyi in Cuatro Ciénegas, Coahuila - García de León, FJ¹; Hendrickson, DA^*2  (1 Laboratoria de Biología Integrativa, Instituto Tecnológico de Ciudad Victoria, Ciudad Victoria, Tamaulipas, México; 2 Texas Memorial Museum and Section of Integrative Biology, University of Texas at Austin, Austin, Texas, U.S.A.)

This paper communicates our recent isolation of microsatellite loci for genetic studies of the polymorphic cichlid, Cichlasoma minckleyi, of Cuatro Ciénegas, Coahuila, México. Microsatellite markers are recognized for several desirable characteristics, including a high mutation rate which results in high polymorphism; they are not subject to selection so the polymorphism is balanced by mutation and genetic drift; and specimens don't have to be sacrificed to be genotyped. Debate continues regarding whether the different morphs of C. minckleyi (molluscivore, detritivore and piscivore) represent different species or different morphs. It's possible that previously used genetic markers (allozymes) with low variability were incapable of answering this question, so we decided to investigate the potential of highly variable microsatellites as a tool to help resolve this dilemma. We captured and took fin clips from 40 individuals of each primary morph (molluscivore and detritivore) from one locality, and from 20 of the rare piscivore morph. The microsatellites had been obtained from a partial genomic bank of total DNA of C. minckleyi. Screening of the bank was done using non-radioactive methods employing DIG oligonucleotide tailing kits. Six types of oligonucleotide probes were used simultaneously in the screening: di, tri and tetranucleotides. One hundred and sixty four positive clones were obtained from a total of 1330 bacteria containing recombinant plasmids with C. minckleyi genome fragments. Thirty of these clones are in the process of being sequenced at the time of this writing and at least 10 loci will be employed for the analysis of genetic differences between morphs. We hope to report results when this paper is presented.

Esta presentación comunica los avances en la obtención de locis microsatélites para el estudio genético de los distintos morfos de Cichlasoma minckleyi en Cuatro Ciénegas, Coahuila, México. Los marcadores del tipo microsatélites son reconocidos por presentar ciertas características deseables entre ellas las que nos interesa comentar es su alta tasa de mutación lo que resulta en un alto polimorfismo; no estar sujetos a presiones de selección por lo que el polimorfismo se mantiene por un balance entre la tasa de mutación y la deriva genética; no se requerir de sacrificar al ejemplar para genotipar a los individuos. Hasta ahora no se ha resuelto el viejo problema de sí los diferentes morfos de C. minckleyi (moluscívoros, detritívoros y piscívoros) representan especies diferentes o solo se trata de un polimorfismo mantenido por presiones de selección durante la ontogenia. Es posible que el empleo de marcadores genéticos (aloenzimas) poco variables no haya permitido explicar eficientemente la presencia de este polimorfismo. Para intentar resolver este dilema se pensó en el uso de microsatélites porque podrían ser informativos debido precisamente a su alta tasa de mutación. Para ello se hicieron colectas capturándose 40 individuos de cada morfo principal (moluscívoro y detritívoro) y 20 del morfo más raro, el piscívoro, en una localidad. Los microsatélites se han obteniendo a partir de una banca genómica parcial de ADN total de C. minckleyi. El escrutineo de la banca se hizo mediante métodos no radioactivos empleando el kit DIG oligonucleotidos tailing. Para el escrutineo de la banca se usaron simultáneamente 6 tipos de sondas oligonucleotidicas con motivos di, tri y tetranucleotidos. Se obtuvieron 164 clones positivos de un total de 1330 bacterias conteniendo plásmidos recombinantes con fragmentos del genoma de C. minckleyi. Se secuenciarán 30 clones y se obtendrán al menos 10 locis que serán empleados para el análisis genético de los diferentes morfos. Se espera que para el momento de la presentación de este ponencia se tenga mas avances en esta investigación.

02:45:00 PM 11/16/00 - Selection forces and extinction risk of the humpback chub (Gila cypha) in the Grand Canyon - Van Haverbeke, DR^*1  (1 United States Fish & Wildlife Service)

The humpback chub (Gila cypha) is an endangered endemic cyprinid inhabiting the Colorado River. Long term stability and survivorship of the humpback chub population in Grand Canyon may be contingent upon the cumulative effects of a number of powerful selective forces. Among these are the effects of environmental stochasticity, heavy parasite loads and limited food resources in the Little Colorado River coupled with mass habitat alteration and predation in the mainstem Colorado River. Management of the species should be inclusive of the long term effects of these forces.

03:00:00 PM 11/16/00 - Exotic species and the decline of amphibians: unintended consequences on a global scale - Vredenburg, VT^*1  (1 Univ. of California, Dept. of Integrative Biology and Museum of Vertebrate Zoology)

A puzzling aspect of amphibian declines is that amphibians, particularly frogs, have been declining even in large protected areas. These habitats are generally thought to be relatively unaltered and undisturbed. However, the introduction of nonnative fish is a common practice throughout the world, and may be an important cause of declines. In the Sierra Nevada, California, the mountain yellow-legged frog has disappeared from >80% of its historic habitat during the past century. We used a survey of >1700 naturally fishless lakes and ponds in two large protected areas to describe the distribution of nonnative trout and mountain yellow-legged frogs. This survey indicated that the distributions of introduced trout and mountain yellow-legged frogs were non-overlapping. To test the hypothesis that introduced trout were driving this pattern, a fish-removal experiment was conducted over a four-year period. Frogs quickly recolonized the fish-removal lakes from nearby source populations, while numbers of frogs in fish containing control lakes remained low and constant. These data suggest that in some areas, the removal of exotic species may be sufficient to reverse the decline of some amphibians.

03:15:00 PM 11/16/00 - Desert pupfish movements among habitats around the Salton Sea - Sutton, RJ^*1  (1 U.S. Bureau of Reclamation)

The desert pupfish (Cyprinodon macularius) is a federally listed endangered species. It is the only fish species endemic to the Salton Sea in southern California. Recently, extreme variability in catch numbers suggests that desert pupfish move among habitats and may use the Salton Sea as a migration corridor to allow mixing of the gene pool. Movements of pupfish were studied among irrigation drains, shoreline pools, and Salt Creek using a mark and recapture technique. Sites were sampled six times during the summer of 1999. Collected pupfish were marked using fluorescent elastomer implants. Unique marks were used for each site. Of the 3,239 pupfish captured, 278 were recaptures, including 27 recaptures at areas different from where they were initially marked. Desert pupfish movements were detected in the southwestern area of the Salton Sea between a drain and a connected shoreline pool. Movements were also detected between Salt Creek and a connected shoreline pool. The marking technique was successful and showed promise for future marking studies, including population estimates.

03:30:00 PM 11/16/00 - Deterioration of Phantom Lake Spring, Jeff Davis County, Texas - Allan, NL^*1  (1 U.S. Fish and Wildlife Service, Austin Field Office)

Phantom Lake Spring is a desert ciénega in west Texas that provides important habitat for a unique assemblage of endemic aquatic organisms, including the federally endangered Pecos gambusia (Gambusia nobilis) and Comanche Springs pupfish (Cyprinodon elegans). In the 1930s, water flowed from Phantom Cave at more than 10 cubic-feet-per-second, but has steadily declined since agricultural development of the spring and surrounding region. The spring is now reduced to a small pool at the cave mouth with few characteristics of spring-run habitat. Present conditions will not support viable populations of fish and aquatic invertebrates. Diminutive amphipod (Gammarus hyalleloides) and a spring snail, Brune’s tryonia (Tryonia brunei), may already be extinct. The specific cause of declining groundwater levels are likely due to pumping of groundwater, compounded by a lack of rainfall to recharge aquifers. Desperate conservation measures are being taken: placing endangered fish in captivity; installing an emergency pumping system to sustain water in the spring outflow; and initiation of an intensive hydrogeological study of the supporting aquifer(s). Phantom Lake Spring is the latest spring failure in this region due to declining groundwater. Past and future groundwater use, limited recharge, and an absence of groundwater management in Texas threatens other desert springs with the same fate.

03:45:00 PM 11/16/00 - Determining the interspecific competitive effects of the invasive African jeweled cichlid, Hemichromis guttatus, on the endemic Cichlasoma minckleyi in Cuatro Ciénegas, México - Williamson, CA^*1; Guevara, AA; Moline, AB; Hendrickson, DA; Marks, JC  (1 Northern Arizona University; 2 Instituto  Tecnológico de Ciudad Victoria; 3 Northern Arizona University; 4 University of Texas at Austin; 5 Northern Arizona University)

The basin of Cuatro Ciénegas lies in the Chihuahuan desert of northern Mexico and contains over 200 springs and pools. The area is a high priority conservation site with many endemic fish and mollusks. Although geographically isolated, the basin is threatened by invading species potentially threatening the native biota; of particular concern is the African jeweled cichlid, Hemichromis guttatus. Since its discovery in 1996 in poza Churince, the fish has appeared in 3 additional habitats, one of which is the beginning of a river, possibly facilitating dispersal to many other sites within the basin. Stable isotope analysis of Hemichromis guttatus reveals that its diet closely overlaps two endemic fish species, the pupfish Cyprinodon bifasciatus and the juvenile form of the cichlid Cichlasoma minckleyi. Local people report that one of the pozas recently invaded by Hemichromis sp. once contained large numbers of C. minckleyi, which are no longer in this habitat, suggesting local extinction caused by competitive exclusion of the native fish. In order to identify competitive interactions between the two species, an in-situ experiment was performed in poza Mojarral Este to test whether intraspecific resource competition in juvenile C. minckleyi was greater than interspecific competition with Hemichromis guttatus. We monitored growth rates and stable isotope composition as indicators of competitive effects.

04:00:00 PM 11/16/00 - Emergency monitoring program for elimination and control of the exotic species of fishes, snails and plants of the Cuatro Ciénegas Valley, Coahuila, México - Lozano-Vilano, ML^*1; García-Ramírez, ME¹; Contreras-Balderas, S²; Contreras-Balderas, AJ¹  (1 Universidad Autónoma de Nuevo León; 2 Bioconservación, A.C.)

The Valley of Cuatro Ciénegas is located between 26o59'N and 102o02'W, with an extension of 1500 km2; ecologically it is one of the most important areas in North America; it has a high number of endemic species that occupy the diferent habitats. In the case of fishes, there are 11 species: Astyanax sp. Notropis xanthicara, Ictalurus sp., Lucania interioris, Cyprinodon atrorus, C. bifasciatus, Gambusia marshi, G. longispinis, Xiphophorus gordoni, Etheostoma segrex, Cichlasoma minckleyi; additionally there are also introduced species like carp (Cyprinus carpio) and African mojarras, Tilapia and Hemichromis sp., that are tolerant to environmental changes, easily adapted, markedly aggresive, and fast breeding; they may cause irreparable damage to the endemic species and ecosystem, may cause lowering of the native populations, and may replace totally the local species as observed in San José del Anteojo, where only a few surviving specimens of Astyanax were found, and through time they may be carried to extinction. Besides, we refer to the presence of the aquarium screw snail and water hyacinth (Eichhornia), which also have a negative effect in the basin native species. The screw snail is present nearly in all the pozas so it is impossible even to think of a way to get control of it due to its fast breeding rate, and its wide distribution. In the case of the water hyacinth we obtained very good results, as to this day there are very few remaining individuals found in recent visits.

El Valle de Cuatro Ciénegas se encuentra en el Estado de Coahuila entre las coordenadas 26o59’ N y 102o02’ W, con una extención de 1500 Km2; es una de las áreas más importantes en América del Norte desde el punto de vista ecológico; en el lugar existe un alto n mero de especies endémicas que ocupan los diferentes hábitats. En el caso de los peces, existen 11 especies: Astyanax sp. Notropis xanthicara, Ictalurus sp., Lucania interioris, Cyprinodon atrorus, C. bifasciatus, Gambusia marshi, G. longispinis, Xiphophorus gordoni, Etheostoma segrex, Cichlasoma minckleyi. Adicionalmente existen especies introducidas, tales como la Carpa (Cyprinus carpio) y las Mojarras africanas Tilapia sp y Hemichromis sp, especies que por su tolerancia a cambios en el medio, su fácil adaptación, su marcada agresividad y acelerada reproducción, pueden causar daños irreparables, a las especies endémicas y al ecosistema, pueden ocasionar disminución de las poblaciones nativas, y pueden llegar a sustituir totalmente a las especies locales como se observó en San José del Anteojo, donde se encontró solo algunos ejemplares de Astyanax sobrevivientes y con el paso del tiempo pueden llevar incluso a la extinción. Aunado a lo anterior, se destaca la presencia del caracol tornillo y del lirio acuático (Eichhornia), quienes también tienen un efecto negativo en las especies nativas de la cuenca. En el caso del caracol tornillo prácticamente esta en todas las pozas y es imposible ni siquiera pensar en alguna forma de control debido a su rápida reproducción y su amplia extención. En el caso del lirio acuático se tienen muy buenos resultados ya que a la fecha son pocos los individuos que se han encontrado en visitas recientes.

04:15:00 PM 11/16/00 - Managing nonnative aquatic species impacts: Implementation of the 1994 Central Arizona Project biological opinion - Stefferud, SE^*1; Marsh, PC²; Clarkson, RW³  (1 U.S. Fish and Wildlife Service, Phoenix, AZ; 2 Arizona State University, Department of Biology, Tempe, AZ; 3 U.S. Bureau of Reclamation, Phoenix, AZ)

In 1994, a biological opinion was issued by the Fish and Wildlife Service (FWS) finding that the Central Arizona Project (CAP) has the potential to introduce and spread nonnative aquatic species in the Gila River basin in Arizona, and thus jeopardize the continued existence of the federally-listed spikedace (Meda fulgida), loach minnow (Tiaroga cobitis), Gila topminnow (Poeciliopsis occidentalis), and razorback sucker (Xyrauchen texanus). To remove jeopardy, the Bureau of Reclamation was charged with a 5-part program, including constructing physical barriers on Aravaipa Creek and San Pedro River, monitoring, information and education, providing funding for management against aquatic nonnatives, and providing funding for other recovery actions for the four listed fish. Unfortunately, opinion implementation has met many roadblocks, including political lobbying to block funding and lawsuits seeking to overturn the opinion. However, the battle for acceptance that a problem with CAP and nonnatives exists, and that resources must be brought to bear on it, is winding down and we are moving forward in the on-the-ground battle to reduce nonnative/native conflicts to a level allowing survival, and hopefully recovery, of Gila basin native fishes. The "umbrella" approach taken by the 1994 opinion attempts to deal with the nonnative issue on a basin-wide basis, although physical barriers are focused at the bottom of the important native fish habitats. This approach is now being extended into the Santa Cruz subbasin, and FWS and Arizona Department of Game and Fish are considering whether a similar "umbrella" approach is appropriate for dealing with effects to native fish from sport fish stockings. There are a number of controversial aspects of the CAP "umbrella" approach. The underlying analysis is "big picture", where the potential for nonnatives to move throughout systems is assessed on a multi-decade basis, with consideration of future changes in weather patterns and human water and land uses. Some believe this is too speculative, resulting in overly negative conclusions. Reliance on a "last-ditch" stand at barriers just below native fish habitats rather than removing problem nonnatives near their point of incursion, is considered risky by some. Difficulty in detecting rare species during monitoring is a drawback in early identification of new incursions of nonnatives or increases in abundance. The emphasis on controlling threats from nonnative fish may be short-sighted in light of recent aquatic invertebrate, disease, and plant invasions. And, use of mitigation concepts where recovery actions are substituted for removal of threats is controversial, although in keeping with trends in the FWS. The success of the CAP approach cannot be judged this early in implementation; but, whether or not it works overall, substantial numbers of recovery actions are underway that would not have happened without the 1994 opinion. Many of those are discussed in a separate paper.

04:30:00 PM 11/16/00 - First true freshwater crab found in US - at Lake Las Vegas! - Cook, AE^*1  (1 Nevada Division of Wildlife)

A number of live Geothelphusa dehaani, a true freshwater crab of the family Potamidae, were found on two separate occasions this year on the shore of Lake Las Vegas, a 320-acre man-made lake 17 miles south of Las Vegas. This is the first known true freshwater crab found in nature the United States. Geothelphusa dehaani is native only to Japan and were most likely introduced via an "altruistic release" from a home aquarium. Life history data and current knowledge of population status will be presented.

04:45:00 PM 11/16/00 - Infection relationships between an exotic digenetic trematode and native fishes in springs of west Texas - McDermott, KS^*1; Brandt, TM¹  (1 USFWS, National Fish Hatchery & Technology Center)

An exotic digenetic trematode tentatively described as Centrocestus formosanus was found in 3 spring systems in west Texas: San Solomon Springs (Reeves Co.), Phantom Lake Springs (Jeff Davis Co.) and San Felipe Springs (Val Verde Co.). These springs are home to several threatened and endangered fishes and degree of infection by the parasite varied among springs, fish species and collection date. Impact on the native fishes appears minimal now, but epidemiology of the parasite is unknown. Six species of these native fishes, comprising two genera, were infected experimentally to determine if there were differences among species and genera in mean parasite load and development of the parasite over time. Twenty individuals of each of the species Cyprinodon elegans, Cyprinodon bovinus, Cyprinodon eximius, Gambusia nobilis, Gambusia gaigei and Gambusia affinis were exposed in the laboratory to parasite cercariae. Significant differences in mean parasite load were found among species of the same genus (p < 0.0001 for Gambusia, p < 0.05 for Cyprinodon), and differences in developmental stage during the same time interval were found between the two genera. Infection and development of the parasite appears to be highly variable among fish species.

05:00:00 PM 11/16/00 - Blue tilapia (Oreochromis aurea) predation on native fishes of the Muddy River, Nevada - Scoppettone, GG^*1; Antonio Salgado, J²; Nielsen, MB³  (1 USGS-BRD, Reno Field Station; 2 USGS-BRD, Reno Field Station; 3 USGS-BRD, Reno Field Station)

Blue tilapia (Oreochromis aurea) have caused native fish decline and extirpation in North American waters. This fish has been described as an omnivorous filter feeder that occasionally forages on benthic invertebrates, macrophytes, and detritus. Competition for food, change in energy flow, and aggression has been suggested as mechanisms by which blue tilapia replace native fish. We examined the guts of blue tilapia collected from a spring-brook trbutary of the Muddy River, Nevada to investigate if they are fish predators. We found that 123 blue tilapia had consumed a total of 346 fish. Among fish consumed were 11 federally listed Moapa dace (Moapa coriacea)and 12 native Moapa White River springfish (Crenichthys baileyi moapae.) This is the first documentation of blue tilapia piscivory contributing to native fish replacement.

08:45:00 AM 11/17/00 - Genealogical relationships among species of the genus Poeciliopsis - Mateos, M^*1; Sanjur, OI²; Vrijenhoek, RC¹  (1 Monterey Bay Aquarium Research Institute; 2 NAOS Marine Lab, Smithsonian Tropical Research Institute, Panama)

We examined mitochondrial Cytochrome b gene sequences to assess phylogenetic relationships among 12 of 18 known species in the genus Poeciliopsis (Cyprinodontiformes: Poeciliidae). Although relationships among several morphologically similar species had been hypothesized, this is the first attempt to infer phylogenetic relationships among members of the genus. Monophyly of the subgenus Poeciliopsis was strongly supported, but the subgenus Aulophallus (represented by Poeciliopsis elongata) clustered in some analyses with the outgroup species, Heterandria formosa, Poecilia butleri and Gambusia sp., rather than with the subgenus Poeciliopsis. Thus, the genus Poeciliopsis as presently constructed may comprise an artificial grouping. Earlier proposals regarding relationships among several closely related species in the subgenus Poeciliopsis were confirmed for the most part and grouped the 11 species into four 4 main clades. However, the relationships among these clades could not be resolved. Furthermore, the Leptorhaphis superspecies group (Poeciliopsis infans, Poeciliopsis lucida, and Poeciliopsis occidentalis) was also found to contain Poeciliopsis prolifica and an undescribed new species. Possible causes for the low resolution of these analyses are mutational saturation (especially in relation to the outgroup taxa) and lineage sorting. Additional taxa including Poeciliopsis retropinna (the only other known member of the subgenus Aulophallus), and additional characters (other genes) are needed to fully resolve these relationships.

09:00:00 AM 11/17/00 - Renovation and habitat restoration for Gila topminnow (Poeciliopsis o.occidentalis) in the Bylas Springs complex - Schleusner, C^*1  (1 USFWS Arizona Fishery Resources Office)

Bylas Springs is a complex of three springs located in the flood plain of the Gila River approximately one mile north of Bylas, AZ on the San Carlos Apache Indian Reservation. Springs S1, S2 and S3, were found to contain natural populations of Gila topminnow in 1968. Flooding in 1980 connected the springs with the Gila River and allowed the invasion of mosquitofish (Gambusia affinis) into S1 and S3. Habitat alterations reduced the surface flow in S2 resulting in the lose of that population of Gila topminnow. Subsequent renovations and barrier construction failed to permanently remove mosquitofish from the springs and by 1996 only a few Gila topminnow persisted in a small pool in S1. From 1996-2000 the U.S. Fish & Wildlife Service Arizona Fisheries Resources Office (AZFRO) planned and executed the successful renovations of S1, S2 and S3. The renovations included barrier construction, riparian rehabilitation and the reintroduction of Gila topminnow into the springs. Cooperators included: AZFRO, Arizona Ecological Services, San Bernardino National Wildlife Refuge, the San Carlos Apache Tribe, Arizona State University, Arizona Game and Fish Department, San Carlos Environmental Protection Agency and the Monsanto Company.

09:15:00 AM 11/17/00 - Winter reproduction of introduced poeciliids in warm springs - Phelps, J¹; Wald, M^*2; Unmack, PJ³  (1 Arizona State University, Department of Biology; 2 Arizona State University, Department of Biology; 3 Arizona State University, Department of Biology)

Numerous poeciliid fishes have been introduced into springs in the western United States, a novel environment due to their constant warm temperatures. This provides an ideal situation for testing of hypotheses relating to factors influencing reproduction, e.g., changes in photoperiod versus seasonal temperature variation. Unfortunately these fish introductions have also resulted in declines of native species, and the only real option for controlling exotics is removal, usually achieved via ichthyocide. Removal is more likely to succeed when populations are at their lowest level and/or non reproductive, since young can inhabit the extreme shallow margins and avoid poisoning. We sampled multiple populations of exotic poeciliids: Gambusia affinis, Poecilia mexicana, P. latipinnis, and P. reticulata autumn through spring, to test if reproduction was occurring based on the presence of developing embryos. Principal sites included springs in Ash Meadows, NV, Rogers Spring (Lake Mead), NV, and Watson Wash, AZ. Single samples were obtained from an additional seven springs. In all species, winter reproductive output was lower than in spring and varied among localities at the same time of year. All guppy populations were reproductive through winter, while the remaining species had some populations which were non-reproductive, while others reproduced only at relatively low levels. These results demonstrate considerable variation, even between geographically proximate springs with similar habitat parameters. If eradication efforts are to be attempted and one were concerned about juvenile survival, January would be the most appropriate time to treat a spring. Reproductive potential would be lowest and marginal habitats coldest (at least at night), hence more likely avoided by juvenile poeciliids.

09:30:00 AM 11/17/00 - Disease resistance in the endangered Gila topminnow - Giese, AR^*1; Hedrick, PW¹  (1 Arizona State University, Department of Biology)

Introduced diseases pose a serious threat to endangered species. Small populations experience reduced genetic variation which may in turn increase susceptibility to novel pathogens. The Gila topminnow (Peociliopsis o. occidentalis) currently exists in four watersheds in Arizona. Using sample fish from representative captive populations maintained at Arizona State University, we tested the resistance of Gila topminnows to a novel pathogen, Vibrio anguillarum, which causes vibriosis in fish. Results indicated differential resistance between populations. Conservation implications are discussed in the context of previously documented genetic variability between populations for genes of the major histocompatibility complex.

09:45:00 AM 11/17/00 - Effect of feeding regime on Gambusia cannibalism - Hubbs, C^*1  (1 University of Texas, Integrative Biology)

Gambusia has a reputation for a high rate of cannibalism in the aquarium literature. In contrasts tests with well fed fish have much lower cannibalism. A series of tests were run with new borns exposed to adults fed daily, every 2 days, 4 days, or 6 days. Those fed daily had much higher survival than those fed infrequently..Much higher survival occured with young in aquaria without predators showing that starvation of young was not the cause for the different survival with adults.

10:00:00 AM 11/17/00 - Genetic status of Leon Springs pupfish after renovation in response to genetic introgression by an introduced pupfish - Echelle, AA^*1; Echelle, AF¹; Kiner, L¹  (1 Oklahoma State University, Zoology Department)

Natural surface waters in Diamond Y Draw include two closely associated, but, except during rare flood events, isolated watercourses, both of which support the endangered Leon Springs pupfish Cyprinodon bovinus. In August 1998, a 400-m segment representing most of the upper watercourse was treated with antimycin A to remove a genetically introgressed C. bovinus x C. variegatus population. Precautions were taken to protect other species of concern (gastropods, amphipods, and an endangered Gambusia). The renovation was followed by release of about 500 genetically pure C. bovinus from a captive stock at Dexter National Fish Hatchery and Technology Center (DNFH). The lower watercourse of Diamond Y Draw was treated differently because the indicated level of genetic introgression was lower (7% vs 15%). In March 1999, all pupfish collected during intensive seining and trapping were removed and about 3,000 fish from the DNFH stock were released in an effort to swamp the introduced genome. After allowing time for reproduction, samples from both watercourses were assayed for 5 diagnostic allozyme loci and a diagnostic RFLP marker for mitochondrial DNA. After 13 months post-treatment for the upper watercourse, the pupfish population appeared devoid of introduced markers. The results for the lower watercourse are forthcoming.

10:15:00 AM 11/17/00 - Hybridization among suckers of the Klamath River basin, California-Oregon - Dowling, TE^*1; Carson, EW¹; Markle, DF²; Cavalluzzi, MR²; Simon, D²  (1 Arizona State University, Department of Biology; 2 Oregon State University, Department of Fisheries and Wildlife)

The Klamath River basin contains a unique assemblage of catostomid fishes, Catostomus rimiculus, C. snyderi, Chasmistes brevirostris, and Deltistes luxatus. Past studies of morphological variation have suggested extensive hybridization among some or all of these forms, placing the latter two species in a precarious state. We examined sequence variation in two mitochondrial genes (NADH dehydrogenase subunits 2 and 4L) from each of these four species to quantify the distribution of variation among geographic locations and species. While local samples were small for many species, this approach identified significant spatial differentiation for some species (e.g., C. rimiculus). These haplotypes fell into four distinct evolutionary lineages: C. rimiculus from the Rogue River, C. rimiculus from the Klamath basin, Deltistes, and C.snyderi-Chasmistes. Comparison of mtDNA haplotypes with morphological identifications was used to examine the extent of hybridization among these forms. Samples identified as C. rimiculus nearly always exhibited distinct mtDNA haplotypes in the same lineages that were rarely found in other species, indicating that this taxon is only rarely involved in the observed hybridization. Deltistes luxatus also tended to possess taxon specific haplotypes, however, some Deltistes exhibited C. snyderi-Chasmistes haplotypes and vice versa. As predicted in previous studies, most hybridization involves C. snyderi and Chasmistes, as most individuals of these two species share phylogenetically similar haplotypes.

10:30:00 AM 11/17/00 - Ecological forces leading to replacement of Pecos pupfish (Cyprinodon pecosensis) by its hybrids with Sheepshead minnow (C. variegatus) - Rosenfield, JA^*1; Angon, T¹; Cain, S¹; Jaeger, J¹; Sandoval, CM¹  (1 University of New Mexico, Dept. of Biology)

Pecos pupfish (Cyprinodon pecosensis) and sheepshead minnow (Cyprinodon variegatus) have hybridized in the Pecos River of New Mexico and Texas. The hybrids are fertile and have replaced Pecos pupfish throughout most of their historic range in a very short period of time. Our previous work revealed that sexual selection (both female choice and male-male competition) contributed to the formationa and rapid spread of the hybrid swarm. We have studied both the growth rates and swimming endurance of Pecos pupfish, sheepshead minnow, and their F1 hybrids. Our results reveal that sheepshead minnow and F1 hybrids enjoy ecological and life history advantages over pure Pecos pupfish. The ecological superiority of sheepshead minnow and F1 hybrids likely reinforces the sexual selection dynamics that we have previously reported. In addition, ecological superiority probably encouraged the spread of the hybrid swarm by contributing to a high intrinsic rate of population growth and high dispersal potential. Implications for conservation and restoration of Pecos pupfish will be discussed.

10:45:00 AM 11/17/00 - Hybridizing subspecies of Poeciliopsis occidentalis - Hurt, CR^*1  (1 Arizona State University, Department of Biology)

Microsatellites and nuclear DNA markers have shown that the two subspecies of Gila topminnows (Poeciliopsis occidentalis occidentalis and Poeciliopsis occidentalis sonoriensis) found in Arizona are quite distinctive. In our preliminary study we attempted to identify possible reproductive differences between the two subspecies. We compared mating behavior during ten minute observations of both interspecific and intraspecific crosses. Despite the similarities in mating behavior, some between subspecies crosses were unable to produce offspring. We then compared brood sizes, and morphological characteristics of the F1 progeny that were produced. Future studies will focus on the fitness of the hybrid offspring.

11:00:00 AM 11/17/00 - Juvenile growth of native fishes in the Little Colorado River: Implications for thermal modification of the Colorado River - Robinson, AT^*1; Childs, MR¹  (1 Arizona Game and Fish Department)

We estimated juvenile growth rates of four native fishes using the von Bertalanffy growth equation and length data from fishes captured during 1991-1994 in the Little Colorado River, a tributary to the Colorado River in Grand Canyon. We compared growth rates to water temperatures for all four species and modeled the consequences of warming the Colorado River (through a retrofit of Glen Canyon Dam) on growth of age-0 immigrants. Juvenile growth rates in the Little Colorado River were fastest for flannelmouth sucker (Catostomus latipinnis), slowest for speckled dace (Rhinichthys osculus), and intermediate for humpback chub (Gila cypha) and bluehead sucker (Catostomus discobolus). Growth rates for three of the four species were positively correlated with water temperature; flannelmouth sucker exhibited the strongest relationship followed by speckled dace, humpback chub, and bluehead sucker. Our model indicates that native fish that disperse into the cold Colorado River (8-12oC) from the relatively warm Little Colorado River within the first three months of life will grow very little by the end of age-0. It is likely that juvenile or older fish that disperse into the Colorado River are more likely to survive than those that migrate as larvae. Survival of native fish larvae that drift from tributaries into the Colorado River could probably be increased if water released from Glen Canyon Dam is warmed during the period of larval drift.

11:15:00 AM 11/17/00 - Upper Colorado River Recovery Program endangered fish stocking results - Czapla, TE^*1  (1 U.S. Fish and Wildlife Service)

Since 1996, experimental and augmentation stockings have been occurring with predominantly razorback sucker (Xyrauchen texanus) and bonytail (Gila elegans) in the Upper Colorado River and Green River subbasins. Over the past few years, hatcheries have been able to produce sufficient numbers of fish to stock. In addition, river and wetland acclamations have provided better survival of smaller fish. One of the greatest successes to date has been the appearance of hatchery-stocked razorback sucker, in a reproductive state, to the spawning bar in the middle Green River. Future stocking developments will more than likely involve wetland depressions and potentially fewer, but larger fish.

11:30:00 AM 11/17/00 - Habitat characteristics used by razorback suckers released into the Imperial Division, Lower Colorado River, California-Arizona; Phase III synopsis and overview of Phase IV - Gurtin, S^*1; Bradford, R¹  (1 Arizona Game and Fish Department, Research Branch)

Between January 1998 and December 1999, we released 100 adult razorback suckers (413-553 mm TL) implanted with ultra-sonic transmitters into the lower Imperial Division, and monitored their use of habitat. Available aquatic habitat within the study area was categorized as main channel, backwater, side channel or impoundment, and was described in terms of surface area and an array of measured habitat characteristics during each survey. We monitored fish distribution among habitat types at 2 to 3 week intervals. The fish used all habitat types, but did not use them in proportion to their availability. Backwaters continued to be selected more frequently than would be expected based on their relative availability. Based on data obtained during Phase III, two separate logistic regression models were developed for predicting use of specific backwaters based on measured habitat characteristics. The models predict use of backwaters poorly, however, non-use of backwaters can be predicted fairly well using select habitat characteristics. The results provide evidence that selection of backwaters by razorback suckers is not dependent on dynamic habitat characteristics (water quality) that we measured, but rather selection is likely based on backwater physical characteristics. Restoration of isolated backwaters (and associated Phase IV research) began in December 1999. Similar research on flathead catfish is expected to begin in autumn 2000.

11:45:00 AM 11/17/00 - Factors affecting the success of stocking woundfin in the Lower Virgin River - Golden, ME^*1; Holden, PB¹; Heinrich, J²; Abate, PD¹  (1 BIO/WEST Inc., Logan UT; 2 Nevada Division of Wildlife, Boulder City NV)

Experimental stocking of woundfin (Plagopterus argentissimus) has been attempted annually in the lower Virgin River since 1994 but survival has been poor. Two potential explanations for the poor survival of stocked fish are that the abundant red shiner (Cyprinella lutrensis) in the stocked reach interact negatively with the woundfin, or that hatchery reared woundfin are not able to adapt to food and habitat changes as they are moved into the riverine environment. We wanted to determine if red shiner numbers could be significantly reduced by mechanical removal, and if stocked woundfin could survive with lowered numbers of red shiners. We mechanically removed red shiners from a 4.5 mile reach of the Virgin River bound by irrigation diversions in May 1999 and stocked the reach with 1700 1-year old woundfin. Stocked woundfin disappeared by late August and woundfin catch rates showed a decline as early as 10 weeks after stocking. Red shiner numbers rebounded by August. We performed a second red shiner removal and woundfin stocking in October 1999 to further test the above hypotheses as well as to test whether larger numbers of young-of-the-year (YOY) woundfin would survive better than lower numbers of 1-year old woundfin. After the October removal, red shiner numbers remained low until June 2000, when numbers of YOY red shiners increased rapidly, and continued to do so throughout the summer. Woundfin catch rates remained stable and relatively high through April 2000. A June 2000 population estimate showed ~ 650 adult fish left in the reach. Even more encouraging than the number of surviving adults, was the fact that the stocked fish successfully spawned as evidenced by the nearly 400 YOY woundfin captured on one of the June sampling trips. The increased survival of the hatchery fish, and their ability to provide recruitment to the reach makes this the most successful stocking of woundfin to date. We removed red shiner and stocked additional woundfin in October 2000. The study is ongoing, but results from May 1999 - October 2000 will be presented.

02:00:00 PM 11/17/00 - Temporal and spatial use of a spawning site in the middle Green River by razorback suckers - Modde, T¹; Kitcheyan, DC^*1; Bowen, Z²  (1 U.S. Fish & Wildlife Service; 2 U.S. Geological Survey)

Sedimentation on spawning sites in the middle Green River has been mentioned as a potential impediment to the reproductive success of razorback suckers (Xyrachen texanus). Recent studies have indicated that fine sediment moves across the Escalante spawning bar in the middle Green River. Description of the timing and distribution of fish on the spawning bar are instrumental in determining whether sedimentation patterns impact hatching success. In an effort to address the relationship of spawning activity to sedimentation patterns, we monitored the timing and distribution of razorbackes suckes on the Escalante spawning bar during the spring 2000 spawning season. Razorback suckers were captured with electrofishing boats on the Escalante spawning area (i.e. Razorback bar) in the middle Green River between 01 May through 17 May 2000. Radio transmitters were externally attached to the dorsal keel of nine fish captured on the spawning bar. Two fish were of wild origin and seven were reared at the Ouray National Fish Hatchery and stocked in previous years. Eight of the nine fish were males and one was a female (hatchery origin). During a two week period, specific locations of razorback suckers were monitored during four individual 24-hr periods. During each 24-hr monitoring period, specific locations of fish were triangulated every hour. In addition, a telemetry logging station continually monitored fish presence on the spawning bar. Six fish were located on the spawning bar and five fish were detected on the bar for at least five days. Fish presence on the bar was related to both temperature and discharge. The distribution and time fish spent on the bar was compared between diurnal and nocturnal hours. Fish presence on the spawning bar occurred in a very localized area with other apparent useable spawning areas not utilized. The duration of time fish were found on the spawning bar was underestimated using electrofishing data only

02:15:00 PM 11/17/00 - Evolutionary history of populations of Pantosteus discobolus from the Little Colorado River in Arizona and New Mexico - Secor, CL^*1  (1 Arizona State University, Department of Biology)

Hypotheses of hybridization and typical evolutionary processes have been proposed to explain complex patterns of morphological variation in populations of Pantosteus discobolus from the Little Colorado River drainage of New Mexico and Arizona. Previous studies have supported both hypotheses, but disagreed on the relative influence of these forces in shaping variation. This study describes variation in mitochondrial and nuclear gene sequence from populations of P. discobolus in the Little Colorado River drainage to test these alternative hypotheses. Analysis of 2 mitochondrial genes indicates the existence of three forms in the Little Colorado River: Pantosteus discobolus, Pantosteus plebeius, and a unique form. Several populations contain polymorphisms of at least two of these lineages, indicating hybridization. Nutria Creek contains Pantosteus discobolus and Pantosteus plebeius haplotypes and localities in the Little Colorado River drainage near Springerville, AZ are mixtures of the unique Pantosteus and Pantosteus discobolus haplotypes. Patterns in nuclear genes from populations near Springerville support the mitochondrial data, but Nutria Creek appears to contain mixtures of nuclear gene alleles from Pantosteus plebeius and the unique form, a result not concordant with mitochondrial data. These results support previous findings and indicate that both forces have played substantial roles in generating patterns of variation observed in Little Colorado River populations of Pantosteus discobolus.

02:30:00 PM 11/17/00 - Distribution, movements, and habitat use of razorback suckers in Lake Mohave, Arizona-Nevada - Mueller, G¹; Marsh, PC²; Knowles, GW^*3; Wolters, T⁴  (1 U.S. Geological Survey; 2 Arizona State University, Department of Biology; 3 U.S. Fish and Wildlife Service; 4 Bureau of Reclamation)

We examined the distribution, movements, and habitat use of 10 wild adult razorback suckers (Xyrauchen texanus) in Lake Mohave, Arizona-Nevada, from November 1994 through July 1997, using sonic telemetry. Movement rates (0.00-17.35 km/d-1) and ranges (mean = 39 km) were similar to those for riverine populations. All study fish returned to spawning sites used in previous years, but they also visited other spawning areas. Spawning females were significantly (P = 0.031) more active than males (480 vs. 87 m/d-1) and moved substantial distances between spawning sites during peak reproduction (1-28 February). Fish became most active (m d-1, km month-1) after spawning and moved to areas known to support higher algal production. Fish were typically within 50 m (P < 0.001) of shore and at average depths between 3.1 and 16.8 (range 0.2 to >30.0 m). Adults were detected throughout the available thermal gradient (12-30 C), but during summer typically had body temperatures between 18 and 22 C. Vertical movements within the water column showed no correlation with depth or time of day, but seasonal shifts suggest fish may regulate body temperature by seeking specific temperatures during reservoir stratification.

02:45:00 PM 11/17/00 - Razorback sucker studies on Lake Mead, Nevada and Arizona, 1999-2000 - Abate, PD^*1; Holden, PB¹; Ruppert, JB¹  (1 BIO/WEST Inc., Logan UT)

Over the previous three years (1996-1999) razorback sucker studies on Lake Mead have followed two separate reproducing populations (at Echo Bay and Las Vegas Bay) and have documented exceptional growth rates of individual fish as well as limited recruitment. After the initial two years of data gathering, the study focus evolved to concentrate on determining when these relatively young fish were recruited and whether other spawning populations were present in the lake. Lakewide larval sampling was conducted and aging of razorback sucker netting mortalities was conducted. Results indicated that indeed, the Lake Mead population was relatively young however no new spawning populations were located.

Research activities for the 1999-2000 study year continued with lakewide larval sampling, development and use of a non-lethal aging technique, and monitoring at the two populations centers where the study was initiated in 1996. Lakewide larval sampling located eleven larval razorback sucker at the Colorado River inflow area. Subsequent netting did not locate any spawners in this area. However, an adult razorback sucker was captured in this area by Arizona Game and Fish in 1998. Also during this study year, aging methods were refined and 11 razorback sucker were aged.  Select razorback suckers caught in trammel nets were anesthetized, and approximately quarter inch segments of the second and third, left pectoral fin rays were surgically removed. These segments were sectioned, sanded and polished, and read under a microscope. Of the 11 fish processed in this manner; four were aged at 13 years, three had an age range of 11-13 years and will be refined further, and four of them were 17 years or older with some refinement possible. Monitoring of razorback sucker at Echo Bay and Las Vegas Bay determined that these populations varied their habitat use during fall/winter and spring/summer seasons as was evident in previous years. Also, both populations successfully produced larvae which were collected throughout the February through May 2000 spawning season.

03:00:00 PM 11/17/00 - Phylogeography of the Rio Grande sucker, Catostomus plebeius, in New Mexico - McPhee, MV^*1; Turner, TF¹  (1 Department of Biology, University of New Mexico)

Population connectivity and demographic rescue probably play an important role in maintaining populations of many stream fishes. Populations of Río Grande sucker (Catostomus plebeius) have become increasingly isolated in the upper Río Grande as the introduced white sucker (Catostomus commersoni) has displaced them from much of the species' historical range. However, the implications of this isolation for persistence of the Río Grande sucker are not clear. The degree to which populations of Río Grande sucker in New Mexico have been connected in the past was examined using phylogenetic and geographic analysis of mitochondrial DNA variation. The results of this analysis are discussed in the context of historical demographic dynamics and future management considerations.

03:15:00 PM 11/17/00 - Escape response performance in the larval razorback sucker, Xyrauchen texanus - Wesp, HM^*1; Gibb, AC¹  (1 Northern Arizona University, Department of Biology)

The razorback sucker, Xyrauchen texanus, is an endangered fish native to the Colorado River system. Previous research suggests that declines in wild populations are due to a lack of larval recruitment. In this study, we tested the hypothesis that poor escape response performance of larval razorback suckers contributes to low recruitment. The larval escape response behaviors of razorback suckers reared at 12 C and 18 C were elicited and digitally recorded over a developmental period to determine 1) if the larvae displayed the escape response and 2) if maximum swimming speed during the response was significantly slower than speeds reported for other fish larva. Response behaviors for 56 razorback suckers were digitized using Didge analysis software. Larval razorback suckers did display escape response behaviors, with speed of the response increasing as length increased during development. In addition, escape response speeds for suckers were similar to those reported for other fish larva at the same size. Preliminary temperature comparisons indicate that maximum swimming speed during the escape shows a Q10 relationship of approximately 0.2. This low value suggests that the colder water temperature does not significantly affect escape response behavior. Thus, it appears that razorback suckers are capable of acclimating to lower Colorado River temperatures and poor escape response performance does not contribute to the lack of recruitment in the wild. Future work will compare escape response performance between the native razorback sucker and an introduced species, the rainbow trout, Oncorhynchus mykiss.

03:30:00 PM 11/17/00 - Effects of temperature on swimming performance of young-of-the-year flannelmouth sucker - Ward, DL^*1  (1 University of Arizona, Fish and Wildlife Cooperative Research Unit)

The flannelmouth sucker, Catostomus latipinnis, is one of the few native fish species that remain in the Colorado River below Glen Canyon Dam. Survival and recruitment of juveniles into the adult population is currently low. Cold swift water discharged below Glen Canyon Dam may impair swimming ability of young-of-the-year (YOY) flannelmouth suckers, potentially leading to increased predation and reduction of available habitat. We conducted fatigue velocity tests on young-of-the-year flannelmouth suckers in the laboratory to evaluate the effects of fish size, fish origin, water temperature, and water velocity on their ability to maintain position in a current. Fish 25 to 115 mm in total length were subjected to incremental increases in water velocity. Tests were conducted at 10 C, 14 C, and 20 C both with and without acclimation to test temperatures. Flannelmouth suckers not acclimated to test temperatures had fatigue velocities similar to acclimated fish. For all fish sizes, swimming ability was inversely related to water temperature. A 10 C decrease in water temperature resulted in up to a 40% decrease in swimming ability. Mean swimming ability of wild-caught YOY flannelmouth suckers was 6 cm/sec higher than the swimming ability of captive-reared flannelmouth suckers. We are currently using information on swimming ability to identify how changes in the temperature of water discharged from Glen Canyon Dam would affect the amount of habitat available for YOY flannelmouth suckers.

03:45:00 PM 11/17/00 - Phylogeography of Sonoran sucker, Catostomus insignis - Douglas, ME^*1; Douglas, MR¹  (1 Arizona State University, Department of Biology and Museum)

Native fish research in western North America has focussed primarily upon federally threatened and endangered (i.e., T&E) species because a sense of urgency is usually implicit, and monies are often available to complete these projects in a short period of time. However, research endeavors to conserve and adaptively manage those species not as yet pushed to the brink of extinction should also be a major imperative. This is because these forms are in a slow (and possibly irreversible) decline throughout their ranges. 'Species of concern' often inhabit smaller tributaries with limited distributions. The Sonora sucker (Catostomus insignis), with a distribution limited primarily to Arizona, falls into this category. Its conservation genetics are of particular interest, for this species is severely impacted by introduced nonnative fishes, habitat degradation, and stream diversion/fragmentation.

In this study, 213 individual C. insignis were examined from 18 populations distributed across the range of the species. Three mitochondrial DNA (mtDNA) genes (ATPase-8, ATPase-6, and ND2) were assayed for each individual, and thirty-nine haplotypes recovered from the combined 1,231 base pairs. Twenty of the 39 (51%) represent transitions at but a single base pair. The molecular variability in C. insignis displayed scant geographic structure. However, the Santa Maria and Bill Williams rivers did cluster together as a single group (at 56% bootstrap support), and an undescribed "Sonora-like" sucker was found in Tularosa Creek (NM) of the Gila River. Hplotypes of this undescribed form are also found in the Virgin and San Juan rivers, which are outside the distribution of C. insignis.

08:45:00 AM 11/18/00 - Contrasting patterns of mitochondrial and nuclear gene introgression in two pupfish endemic to the Cuatro Cienegas basin, Mexico - Carson, EW^*1  (1 Arizona State University,Department of Biology)

The pupfishes Cyprinodon bifasciatus and C. atrorus are endemic to the Cuatro Ciénegas basin, Mexico where they locally hybridize under natural and artificial conditions. A previous basin level survey of mtDNA sequence variation revealed that historic, natural hybridization between these species resulted in complete replacement of C. bifasciatus mitochondrial genome by that of C. atrorus. To gain a more comprehensive understanding of the patterns and effects of hybridization between these species, a similar survey of sequence variation was conducted at three nuclear gene loci (recombination activation gene-1 [RAG-1], creatine kinase-A [CK-A], and triosephosphate isomerase-B [TPI-B]). Morphologically pure populations of C. bifasciatus and C. atrorus were fixed for alternate alleles at all three loci. Two morphologically intermediate populations segregated for C. bifasciatus and C. atrorus alleles at each locus, indicating hybridization at these locations. Such hybrid populations were primarily composed of backcross genotypes, but possible F1 individuals were also identified.

09:00:00 AM 11/18/00 - Temperature effects on growth of juvenile humpback chubs - Figiel, C Jr^*1; Jackson, M¹; Ulibarri, M¹  (1 U.S. Fish and Wildlife Service)

Humpback chub Gila cypha are threatened with extinction due to habitat modifications associated with water development. As a result of dam construction, temperatures in the mainstem Colorado River are too cold for successful recruitment of humpback chub and other endangered fishes. Management options include releasing warmer water for native fishes, however the impact of changes in water temperature on fish growth and survival is needed. We examined the efffects of three temperatures (21 C, 24 C, 27 C) on growth of juvenile humpback chub previously reared at 12 C, 18 C, and 24 C. Growth rates (determined by total length and weight) were lower at 21 C compared to growth of fish grown at 24 C and 27 C. Fish previously reared at 12 C had a higher growth rate at all temperatures in this experiment compared to fish previously grown at 24 C, although did not catch up in size or weight. These findings suggest that warm water releases can benefit humpbacks by increasing their growth and thus shortening exposure to gape-limited predators but does not compensate for the previous effects of colder water.

09:15:00 AM 11/18/00 - Natural selection on an allozyme locus in the White Sands pupfish? - Miller, KM^*1  (1 North Dakota State University)

The White Sands pupfish (Cyprinodon tularosa), listed as Threatened in New Mexico, occurs in 4 habitats that vary widely in environmental salinity. At Malpais Spring, pupfish encounter a salinity gradient with salinity concentrations increasing from springhead (3.75 ppt) to marsh (9.23 ppt). The frequency of Pgdh100 (Phosphogluconate dehydrogenase) differed between low and high salinity sites at Malpais Spring. This suggests that natural selection may be acting to maintain the polymorphism at the Pgdh locus. Alternatively, genetic drift may explain the spatial variation for Pgdh100. However, if the pattern is due to drift, congruent patterns of population structure should also be reflected in neutral molecular markers such as microsatellites. In this study genetic analyses of two microsatellite loci (WSP-02, WSP-11) were conducted to assess genetic structure within Malpais Spring. Microsatellite allele frequencies did not differ between upper and lower Malpais Spring (X2 = 8.648, P = 0.28). This finding is consistent with the hypothesis that Pgdh is under selection. To further explore the potential selective impact of salinity, experiments were conducted involving the exposure of pupfish eggs to high (35 ppt) and low (3.5 ppt) salinity. In general, high salinity had a negative effect on hatching success. Although pupfish are known to have a wide tolerance for environmental salinity, these data suggest that salinity may be an important selective factor in White Sands pupfish. The potential of such selective forces acting on threatened species may be critical in the development of management plans, especially if translocation to novel environments is necessary.

09:30:00 AM 11/18/00 - Translocations and costs of parasitism for White Sands pupfish (Cyprinodon tularosa) - Collyer, ML^*1  (1 North Dakota State University)

Translocations of the White Sands pupfish (Cyprinodon tularosa), a New Mexico State threatened species, have resulted in altered parasite communities for recently established populations. Native populations of C. tularosa occur at Malpais Spring and Salt Creek. Based on their genetic uniqueness, and their reproductive isolation in ecologically different habitats, Stockwell et al. (1998) determined that these populations represent two evolutionarily significant units (ESUs) of C. tularosa. Fish were translocated from Salt Creek to Mound Spring and Lost River in the 1970's; thus, the Salt Creek ESU has been twice replicated. White grubs (Diplostomatidae) heavily infect fish at Mound Spring, but do not infect fish in the Salt Creek and Lost River populations. Correlative evidence suggests that parasitism of C. tularosa by white grubs is costly in terms of host fitness. Parasite load shows a seasonal pattern with significantly lower levels of infection for fish during the winter (F3,104 = 3.195, P = 0.027). Based on the parasite life cycle, these data suggest that heavily infected fish have lower winter survival. Here I report experimental results on the effects of parasitism by white grubs on the survivorship and life history traits of C. tularosa over a 60-day period. Fish that were parasitized had significantly reduced survivorship (X21df = 13.67, P<0.001), growth rates (ANCOVA: F1,71 = 4.135, P=0.037) and fat storage (ANCOVA: F1,71 = 11.5, P = 0.001) compared to unparasitized fish. I conclude that parasitism by white grubs is likely to impact host fitness. Further, these data suggest that the Mound Spring habitat is not a suitable habitat for replication of the Salt Creek ESU.

09:45:00 AM 11/18/00 - Temporal genetic variation and the effective population size in the silvery minnow, Hybognathus amarus: a preliminary evaluation - Turner, TF^*1; Alo, D¹  (1 University of New Mexico, Department of Biology and Museum of Southwestern Biology)

We studied temporal genetic variation at a panel of nuclear DNA microsatellite loci in the endangered Río Grande silvery minnow. Samples were taken at a single location over two generations (1999-2000) to estimate levels of genetic diversity in the species, and to evaluate temporal changes in genetic diversity. Preliminary analysis indicated a higher frequency of heterozygotes than expected under Hardy-Weinberg equilibrium for three of five loci studied. Short-term heterozygote excess is expected when a population has undergone recent and dramatic declines in abundance. Temporal shifts in genetic diversity were used to estimate the current (variance) effective population size, but accuracy of these estimates may be compromised by small sample sizes (ca. 50 individuals per year class).

10:00:00 AM 11/18/00 - Comparison of Cichlasoma minckleyi ram and suction feeding kinematics to those of other cichlid fishes - Hulsey, CD^*1  (1 Center for Population Biology:  Section of Evolution and Ecology, University of California, Davis)

The feeding performance of biting morphs of Cichlasoma minckleyi on elusive prey was compared to the feeding performance of six other species of cichlids. Using high speed video (500 fps), we measured the contribution of both ram and suction to feeding strikes. Suction was quantified as the linear distance that the prey moved towards the predator once the predator began the fast opening portion of the gape cycle during the strike. We measured ram, the linear distance the predator travels towards the prey, in two ways. We quantified both the movement of the predator's body towards the prey and body movement plus the additional contribution of upper jaw protrusion towards the prey. To quantify the strike variables of each cichlid species, we used three individuals that ranged in size from 65 to 85 mm. We examined 15 brine shrimp, Artemia sp., and up to 5 guppy, Poecilia sp., capture events per individual. Surprisingly, the trophically diverse group of cichlid species examined did not differ from one another in the amount of suction produced when capturing either prey type (p < 0.65). Species did differ significantly in the amount of ram used during prey capture but only when feeding on the more elusive guppies (Body Ram: p < 0.056; Body + Jaw Ram: p < 0.047). Biting C. minckleyi displayed less body ram than the piscivores Cichla ocellaris, Crenicichla gayi, and Petenia splendida, but did not differ from Cyprichromis leptosoma or Astrotonotus ocellatus. The same pattern was found in the body + jaw ram components of strikes except that C. minckleyi had significantly more body + jaw ram than Cyprichromis leptosoma. In general, we found that the distance traveled during the predatory strike of a cichlid fish is composed of several times more ram than suction and that suction does not vary among predators or prey type. This analysis has important implications for the dichotomy of fish into ram versus suction feeding types and suggests that composite indices of feeding performance such as ram/suction ratios should be regarded with caution. Finally, it is predicted that if the piscivorous morphs of C. minckleyi were compared to biting morphs, the piscivorous morphs will not differ in the amount of suction produced but instead should use more ram during prey capture.

10:15:00 AM 11/18/00 - Genetic variation in speckled dace from the Virgin River basin (UT,  AZ, NV) - Douglas, MR^*1; Warrack, SR¹; Douglas, ME¹  (1 Arizona State University, Department of Biology and Museum)

The Virgin River has been subjected to water removal for agricultural purposes since mid-1800's. Of late, regional urbanization and tourism have also absorbed much of the basin's water. These conditions, coupled with introductions of nonnative fishes, have seriously impacted endemic fishes. Several are now listed as endangered, while others are "of concern."

The speckled dace (Rhinichthys osculus) is widespread throughout western North America, and concomitantly in the Virgin River basin. Interestingly, it is neither endangered nor "of concern" to resource agencies. The basin-wide distribution of genetic diversity in this fish could be a model for other species in the basin, especially those now greatly restricted in range and abundance. To accomplish this, 10 individuals were sampled from each of the following 13 sites (east to west): North fork of Virgin River, La Verkin Creek, above Washington Field's diversion, at mouth of Santa Clara River, Santa Clara below Gunlock Reservoir, Santa Clara at Veyo, Moody Wash, Virgin River at Littlefield (AZ), Beaver Dam Wash above confluence (AZ), Beaver Dam Wash above Montoqua (UT), Virgin River at Mesquite (NV), Meadow Valley Wash (NV), and Condor CN (NV). MtDNA was isolated from muscle and 2 regions of the molecule (ATPase 8 and 6) were amplified and sequenced. Preliminary results indicate considerable variability within and among populations, and suggest differentiation between several tributaries vs mainstem, and in the mainstem above vs below the Virgin River narrows. Management implications are discussed.

10:30:00 AM 11/18/00 - Theoretical and empirical investigations of larval fish drift in Aravaipa Creek, Arizona - Keithley, RK^*1; Schwemm, MR¹; Minckley, WL¹  (1 Department of Biology, Arizona State University, Tempe, AZ.)

Theoretical models and field collections were utilized in analysis of larval fish drift in Aravaipa Creek, Arizona. Neutrally buoyant gel beads, a surrogate for larval fish, were used as a modeling device to describe distribution of drift during downstream displacement. Diffusive spread of the beads was approximated by applying the one-dimensional diffusion-convection equation. Drifting larval fishes were collected from March through May 2000, and were compared qualitatively to the diffusion model. In addition to providing insight into patterns of dispersal, the study encompassed several aspects of larval fish ecology, e.g. species composition, drift densities, and diel periodicity.

10:45:00 AM 11/18/00 - A newly documented locality for the desert chub (Gila eremica) in a tropical canyon, Río Mátape basin, Sonora, México - Varela-Romero, A^*1  (1 DICTUS, Universidad de Sonora, Hermosillo, Son.)

The desert chub ({Gila eremica}) has been recently described as a species surviving to extreme desert conditions in the Sonora and Matape River Basins in Sonora. Traditionally it has been recorded occupying the headwaters of the principal riverbeds of their distribution. In the last summer, two populations of the desert chub were registered in tank habitats in the La Balandrona and Las Pirinolas Canyons in the south portion of the Sierra El Aguaje in the extreme southwest of the Río Mátape Basin. 18 (52mm to 140mm LT) and 45 (23mm to 75mm LT) specimens of {G. eremica} were collected in tanks with rock and sand bottoms with important coverages of palms vegetation in the Cannons La Balandrona (28^o^02'16.1" N and 111^o^07'36"Wr, 350 m elevation) and Las Pirinolas (28^o^05'32.9"N and 111^o^02'15.0"W, 200 m elevation) respectively. The tanks, connected by shallow arroyos in most of the situations, varied in depth of 0.5 to 2.5 m in dry season, and the fisicoquemical variables looks acceptable for the development of the native fish. La Sierra El Aguaje include too the Nacapule, Las Barajitas and Aguaje Robinson Canyons between other, and represent tropical vegetation areas surrounded by desert vegetation where they have been registered endemic plants, geographically isolated tropical species and native fauna with interest for the conservation. This singular desert region of the Central Coast of Sonora, not only offers a favorable panorama for the protection and conservation of this endemic fish, it also represents an invaluable region of the Sonoran Desert.

El charalito del desierto (Gila eremica) ha sido recientemente descrito como una especie sobreviviente a condiciones desérticas extremas en las cuencas de los Ríos Sonora y Mátape en Sonora. Tradicionalmente se ha registrado ocupando las cabeceras de los cauces principales de su distribución. En el verano reciente, dos poblaciones del charalito del desierto fueron registradas en habitats de tanques en los Cañones La Balandrona y Las Pirinolas en la porción sur de la Sierra El Aguaje en el extremo suroeste de la Cuenca del Río Mátape. Diéz y ocho (52mm a 140mm LT) y 45 (23mm a 75mm LT) especímenes de G. eremica fueron colectados en tanques con fondos de roca y arena con importantes coberturas de vegetación de palmas en los Cañones La Balandrona (28o02'16.1" N y 1o07'36" O, 350 msnm) y Las Pirinolas (28o05'32.9" N y 11o02'15.0" O, 200 msnm) respectivamente. Los tanques, conectados entre si por arroyos someros en la mayoría de las situaciones, variaron en profundidades de 0.5 a 2.5 m en época de secas y las variables fisicoquímicas permanecieron aceptables para el desarrollo de los peces nativos. La Sierra El Aguaje comprende además los cañones Nacapule, Las Barajitas y El Aguaje de Robinson, entre otros, y representan áreas de vegetación tropical rodeada por vegetación desértica donde se han registrado especies de plantas endémicas, especies tropicales aisladas geográficamente y fauna nativa de interés para la conservación. Esta singular región desértica de la Costa Central de Sonora, no sólo ofrece un panorama favorable para la protección y conservación de éste pez endémico, sino de una invaluable región del Desierto Sonorense.

11:00:00 AM 11/18/00 - Native fish conservation and the Central Arizona Project - Marsh, PC^*1; Clarkson, RW²; Stefferud, SE³  (1 Arizona State University, Department of Biology, Tempe AZ; 2 U.S. Bureau of Reclamation, Phoenix Area Office, Phoenix AZ; 3 U.S. Fish and Wildlife Service, Arizona Ecological Services Field Office, Phoenix AZ)

U.S. Fish and Wildlife Service (FWS) in 1994 issued a Biological Opinion on the transport and delivery of Colorado River water to the Gila River basin via U.S. Bureau of Reclamation (BR) Central Arizona Project. The opinion determined the project would jeopardize continued existence of four native fishes, loach minnow (Tiaroga cobitis), spikedace (Meda fulgida), razorback sucker (Xyrauchen texanus) and Gila topminnow (Poeciliopsis occidentalis), and adversely modify critical habitat of the first three. The reasonable and prudent alternative necessary to remove the threat of jeopardy included annual transfer of $500,000 for 25 years from BR to FWS. These funds are to be used for conservation of Gila River basin native fishes and non-native fish control. Potential projects are developed by a multi-agency technical team working in cooperation with a suite of regional conservation experts, and selection for funding is aided by a long-term guidance document. Highest priority is given to projects that benefit all native fishes, for example, development of taxon-specific piscicides and protection of key recovery areas. Through autumn 2000 a total of $1.5 million has been transferred over three fiscal years and allocated to 58 individual or continuation projects with a total cost of $1.73 million; five other projects valued at $589,000 have been identified for the next FY. Ten of the 58 projects have been completed, nine have been deleted, four are currently underway, and the remainder is yet to be contracted. Individuals and organizations interested in Gila River basin native fishes are encouraged to contact BR or FWS with their ideas.

11:15:00 AM 11/18/00 - Conservation genetics of Siphateles bicolor, a threatened desert endemic - Serway, CN^*1; Wilcox, JL¹; Stein, J²; Martin, AP¹  (1 University of Colorado at Boulder & Nevada Division of Wildlife; 2 Nevada Division of Wildlife)

The Great Basin is home to many threatened endemic aquatic species, including the tui chub, Siphateles bicolor (formerly Gila). Populations of this monotypic minnow living in isolated spring habitats throughout Nevada have been severely threatened by anthropogenic habitat degradation and the introduction of exotic species. The distinct morphological differences seen between populations has caused much dispute over the number of extant subspecies, leaving managing agencies unsure of which populations are in need of attention. This study employs mitochondrial DNA to accurately determine relationships among the multiple populations and to understand whether current descriptions reflect evolutionary significant units or phenotypic plasticity. Three main clades were identified, two of ancient (mid-Pliocene) origin while the third consisted of recently isolated lineages (late Pleistocene) with incomplete sorting of ancestral variation. Little correlation was found between geographic location and phylogenetic relatedness. Additional research consisting of 2 microsatalite loci, although preliminary, supports the mitochondrial data. This offers managing agencies a more clear picture as to which populations should be targeted for conservation, while providing additional insight on both the time scales at work and the processes driving the evolution of desert fishes.

11:30:00 AM 11/18/00 - Monitoring and conservation efforts for the desert pupfish Cyprinodon macularius and the Quitobaquito pupfish, C. eremus, on La Biosefera Alto Golfo de California y Delta del Rio Colorado  y La Biosfera El Pinacate y Gran Desierto de Altar, and Baja del Norte - Minckley, CO^*1; Campoy-Favela, JR²; Davila-Paulin, JA³; Thorson, MS¹; Schleusner, CJ⁴  (1 Arizona Fisheries Resources Office, U.S. Fish & Wildlife Service,  60911 Hwy 95, Parker, Arizona 85344; 2 La Biosefera Alto Golfo de California y Delta del Rio Colorado, SEMARNAP, A. P.452, San Luis Rio Colorado, Sonora, Mexico, C.P. 83400; 3 La Biosfera El Pinacate y Gran Desierto de Altar, SEMARNAP,  A.P. 125, Puerto Penasco, Sonora, Mexico, C.P. 83550; 4 Arizona Fisheries Resources Office, U.S. Fish & Wildlife Service, P.O. Box 710, Peridot, Arizona 85542)

This presentation discusses conservation efforts for pupfish during 2000, on two Mexican biospheres located in northern Sonora, Mexico and in Baja del norte. Management efforts for pupfish on the lower gulf biosphere include the construction of livestock exclosures at several spring sites within the El Doctor Marsh. The vegetative response of the bulrush and cattails has been so great within these exclosures that it threatens the open water habitat for the pupfish. Artificial disturbance will be required to maintain the springs as refugia for pupfish. This is a joint effort between the biosphere and the U.S. Fish & Wildlife Service (Service).

On the Pinacate Biosphere, efforts are being made to remove salt cedar and other nonnative plants from a one kilometer core area along the Sonoyta River to secure an area for the Quitobaquito pupfish. This will be done by installing a low, water-inflated dam to increase habitat. Cattle will also be fenced out of this area. Discussions have also been held with the University of Sonora about establishing a refugia at their facility in Puerto Penasco. This project is a joint effort between the Biosphere and AZFRO-Parker, Cabeza Prieta NWR, the International Sonoran Desert Alliance, Organ Pipe National Monument and local high schools.

Activities for pupfish in Baja California include establishing another population of the desert pupfish found in Laguna Salada. This site will be at Guadalupe Canyon, a drainage entering Laguna Salada.

Additionaly, education programs are being developed on both biospheres, and at the geothermal plant at Cerro Prieto, to provide information to the public, local municipalities, and schools. These programs include display aquariums, presentations, and literature on pupfish.

11:45:00 AM 11/18/00 - Aspects of the life history of the roundtail chub, Gila robusta (Cyprinidae), in the Yampa River canyon, Colorado - Ross, ST^*1; Modde, TC²  (1 Department of Biological Sciences, University of Southern Mississippi; 2 U.S. Fish and Wildlife Service, Colorado River Fish Project)

The Gila robusta complex includes three large, morphologically variable cyprinid species native to the Colorado River drainage. All three members of this complex, G. cypha, G. elegans, and G. robusta, occur (or occurred) in the Yampa River Canyon. Both G. elegans and G. cypha are federally listed as endangered with the former likely extirpated from the Yampa River; only G. robusta is still unlisted and relatively common although it is a candidate for listing. Life history aspects, including age and growth, age at first reproduction, and secondary sex characteristics such as tubercle development are poorly known for G. robusta, and indeed for all three species. Consequently, in addition to providing information directly on G. robusta, this species may be considered a surrogate to better understand life history characteristics of G. elegans and G. cypha. Gila robusta were collected during July in 1998 and 1999 by angling and electrofishing in the Yampa River Canyon in Dinosaur National Park. Fish ranged from 90-365 mm SL. Ages were determined from scales, opercular bones and otoliths. Because data analysis is still ongoing, only data from 1998 are reported here. Actual verification of growth checks as annuli is difficult due to limited seasonal access to the study area, thus eliminating marginal increment analysis. Verification will be based on age changes of modal size groups collected in subsequent years. Based on presumed annular marks in otoliths, ages ranged from 2û21 years. Annuli from opercle bones generally agreed with otolith data. Presumed ages based on scales were less than those based on otoliths after 8 years. Based on preliminary data, gonadal maturation occurs by age 8 for females and 7 for males. Detailed field sketches of tuberculation patterns were made for 8 fish (5 males, 3 females). Both males and females show tubercle development on the head, dorsum, and pectoral rays. Although data are limited, intensity of tuberculation is positively related to gonadal development.

02:00:00 PM 11/18/00 - A national program for monitoring stream conditions in the western United States - Baker, JR^*1; Kepner, WG²; Chaloud, DJ²; Kinney, WL¹; Hamilton, ME¹; Jones, KB²  (1 Lockheed Martin Environmental Services; 2 U.S. Environmental Protection Agency, Las Vegas)

The U.S. Environmental Protection Agency recently initiated a four-year survey of streams in the Western United States as a component of the Environmental Monitoring and Assessment Program (EMAP). EMAP is developing indicators to monitor and assess the condition of ecological resources at a regional or state level of scale. This is accomplished by randomly selecting sites and by obtaining a representative sample of biotic assemblages along with physical and chemical measures. These data are then used to estimate the biological integrity of the sites. Since the stream sites are randomly selected, the data collected can be used to make regional and statewide estimates of stream condition. States included in the survey are Arizona, California, Colorado, Idaho, Montana, Nevada, North Dakota, Oregon, South Dakota, Utah, Washington, and Wyoming. An overview of the survey design, logistics, sample design and a preliminary account of fishes from stream sites sampled in Arizona, Nevada, and Utah will be presented.

02:15:00 PM 11/18/00 - Identifying areas of conservation priority for native fishes in the Gila River Basin using GIS - Unmack, PJ^*1; Minckley, WL¹  (1 Arizona State University, Department of Biology)

Southwestern North America provides a stark example of a depauparate and unique native fish fauna decimated by environmental depredation, introduced non-native species, and other factors. The fauna has declined to the point where most species are biologically imperiled. Due to the restricted availability of surface water and concern for the continued existence of the fauna, the region has been intensively sampled and substantial records exist from which to build a comprehensive database of fish occurrences. As reported here before, individual records for the Gila Basin have been compiled from museum records, primary, and "gray" literature. Data were geographically referenced using GIS. Several components were incorporated into determining conservation priorities: present day richness for native species, Threatened and Endangered species richness, percentage and absolute decline in native fishes, non-native species richness, etc. Our results consisted of a table containing many factors (as outlined above) summarized by watersheds and stream reaches. These data were best suited for graphical display. There are many ways conservation priorities can be determined, we incorporated two factors, the ratio of threatened species richness to total species richness, and intactness (whether any species had been lost or not). These were divided into seven categories with the number of watersheds for each shown in parentheses: no fish records (117), not intact and no threatened species (88), intact and no threatened species (25), not intact and 15-35% threatened species (15), intact and 15-35% threatened species (17), not intact and >40% threatened species (11), and intact and >40% threatened species (6). Results and data from our analyses are available at http://fish.la.asu.edu/gilafish.

Several problems arose. How should a stream that once had seven native species but now has only four natives and many introduced species rank relative to one that has only ever had two native fishes and today has no exotics? Distribution of early collection records was biased by access limitations rather than covering representative areas. In recent years, few vouchers have been retained, and introduced species were rarely kept, now most recent records tend to be in "gray" literature which cannot be confirmed, checked for misidentifications, or re-examined when taxonomic changes occur. Another problem is the lack of negative data, it is not possible to know if species weren't collected because they were not present, or if they were not adequately sampled. GIS provided an excellent means by which this type of data can be analyzed. Assimilation of data into a GIS allows ease of display and high query capability. More importantly, GIS allows spatial analysis of relations among biotic and abiotic factors, including fish occurrence relative to permanency of water, geologic structure, stream gradients, altitude, land use, species associations, etc.

02:30:00 PM 11/18/00 - Cienega Creek stream restoration project - Simms, JR^*1  (1 US Bureau of Land Management)

A 1.4 mile reach of Ciénega Creek, Pima County, Arizona was disturbed by farming activities in the 1970's. Modifications include 3 dams, one levee and a road crossing/canal system that diverts water away from 3 miles of Ciénega Creek into a small tributary. This disturbance of the creek has effected riparian development and habitat for a multitude of special status species including Poeciliopsis occidentalis (Gila topminnow), Gila intermedia (Gila Chub), Empidonax traillii (south western willow flycatcher), Thamnophis eques (Mexican garter snake) and Rana chiricahuensis (Chiricahua leopard frog). The hydrologic and ecologic processes of this stream segment were restored using principles of stable natural channel morphology with the idea that restoration would be self-sustaining under the current sediment load and hydrograph. Key aspects of the design were to maintain the proper pattern, dimension and profile of the segment being restored. Structures were removed, the diversion canal blocked, road crossing moved and reconstructed, and a new stream segment constructed. Revegetation and 2 grade control structures composed of boulders were used to stabilize areas at risk of erosion. Monitoring has begun and will be used to gage the level of physical and biological change resulting from stream restoration efforts.

02:45:00 PM 11/18/00 - Recovery status of the Apache trout Oncorhynchus apache - Ruiz, LR^*1; Gatewood, T²; Novy, JR³; Young, K⁴; Ward, J⁵  (1 USFWS, Arizona Fishery Resources Office; 2 White Mountain Apache Tribe, Wildlife and Outdoor Recreation Division; 3 Arizona Game and Fish Department; 4 Arizona Game and Fish Department; 5 USFS, Apache/Sitgreaves National Forest)

Listed as endangered in 1973 and downlisted in 1974 to threatened, the Apache trout Oncorhynchus apache is one of three trout native to the Southwestern United States. Historically, the trout was distributed throughout the headwaters and tributaries of the Salt and Little Colorado rivers and extant populations are now protected by natural barriers in headwater reaches of streams that originate in the White Mountains of Arizona. The U.S. Fish and Wildlife, U.S. Forest Service, Arizona Game and Fish Department, and the White Mountain Apache Tribe cooperatively lead the recovery efforts of the Apache trout that include the following activities: 1) surveys and inventories of Apache trout in historical habitat; 2) analytical techniques that allow for verification of genetic purity; 3) construction of artificial barriers to prevent upstream migration of non-native salmonids that impede any future hybridization with rainbow trout O. mykiss and cutthroat trout O. clarki and competition with and predation by brown trout Salmo trutta and brook trout Salvelinus fontinalis; 4) renovation to remove hybridized and non-native salmonids from historical habitats; 5) replication of pure Apache trout populations into renovated habitats; 6) hatchery propagation of Apache trout; and, 7) education and outreach programs.

03:00:00 PM 11/18/00 - Significance of fluvial, sand-bed habitat to desert river minnow conservation - Hoagstrom, CW^*1  (1 U.S. Fish and Wildlife Service, New Mexico Fishery Resources Office)

The native fish assemblage of desert and plains rivers includes a suite of fluvial specialist minnows(Cyprinidae). These rivers historically consisted of a shifting sand-bed, low, sparsely vegetated banks, and a wide floodplain. Efforts to quantify physical or biological conditions of sand-bed rivers have been limited in scope and have only been linked anecdotally to the life history of native fishes. Sand-bed rivers (rivers with an unlimited sand supply and sand to the depth of maximum scour) are hydraulically unique. In-channel morphology (bed configuration) is directly determined by mean and local velocity. Different bed configurations create and sustain different sand-bed characteristics (e.g. particle size, insterstitial space) which affects connectivity between surface water, parafluvial water, and groundwater. This connection is critical to in-stream nutrient cycling and primary productivity. Historical conditions provided multiple bed configurations(habitat types) at all times. The abundance, extent, shape, and location, of each bed configuration was constantly changing as discharge varied and bed sand advanced downstream. Activities associated with human development (e.g. flood control, sediment control, flow diversion, groundwater depletion, channelization) have intentionally interrupted and eliminated the very processes which maintained fluvial, sand-bed habitat. Resulting degradation has caused species loss but the true nature of such loss is difficult to quantify due to lack of ecological understanding. This lack makes river restoration for native fish conservation a challenge. The upper Río Grande Basin (upstream of the Fall Line) provides an example of the concurrent decline of fluvial, sand-bed conditions and fluvial specialist minnows. Historical accounts document that 1900 miles of the mainstem Río Grande, Río Chama, and Pecos River were dominated by fluvial, sand-bed conditions. Fluvial specialist minnows were historically collected from the majority of this stretch. Reaches from which fluvial specialist minnow occurrence was poorly validated (few collections or individuals) were most poorly sampled and most heavily impacted by early developments including upstream dams, upstream diversion, channelization, and groundwater mining. Currently, phantom shiner (Notropis orca) is extinct. Río Grande silvery minnow (Hybognathus amarus) is confined to 283 km of the Río Grande and bluntnose shiner(Notropis simus) is restricted to 148 km of the Pecos River. Both reaches maintain sand-beds but fluvial conditions are endangered. Speckled chub (Macrhybopsis aestivalis) and Río Grande shiner (Notropis jemezanus) persist in the remote canyonlands of the lower Pecos and Big Bend(Río Grande), TX. However, they are only abundant in the middle Pecos River, NM where they are associates of bluntnose shiner. Primary threats to fluvial specialist minnows are water and sediment deprivation (habitat destruction). If they are to be conserved, unique ecological features of fluvial sand-bed channels must be recognized, described, protected, and restored.

03:15:00 PM 11/18/00 - Status of the Amargosa toad and habitat within the Oasis Valley, Nevada - Stein, JR^*1; Hobbs, BM¹; Wasley, GA¹  (1 Nevada Division of Wildlife)

During the summer of 1998 and 1999 we captured, tagged, and released 1,431 adult Amargosa toads, Bufo nelsoni, and estimated a population of 4,697 adult toads occurring in our study area. Our study area encompassed 13 survey locations comprised of 121 acres or approximately 20% of emergent vegetation associated with wetlands and surrounding transition and upland habitats present in the Oasis Valley. Although growth rates and movement distances were highly variable we were able to determine home ranges and growth rates. It was determined that male toads moved an average of 72.9 meters and female toads moved an average of 44.99 meters from capture to recapture. Five toads moved between survey locations during the study, the largest movement was 1,406 meters. Growth rates were identical for males and females, although females attained a larger ultimate size. Toad capture locations demonstrated a significant preference for south by southwest aspects. Toad densities per hectare were highest in areas that are primarily urban and lower in areas which most represent historic habitat conditions. Toads also showed a strong preference for transition and disturbed habitats with bare earth which allows the use visual acuity for foraging. These results plus survey effort results from 2000 will be presented.

03:30:00 PM 11/18/00 - Recent changes in fish statistics: Verde River, Arizona - Rinne, JN^*1  (1 USDA, Forest Service, Rocky Mountain Research Station)

Decline in total fish abundance, changes in community composition, dramatic decline to disapparance of native spcies, increase in nonnative species, and lack of recruitment of native species have recently been recorded in the upper Verde River, Arizona. Hydrographs during these changes in fish statistics have included both peakflow, flood events and the current, sustained (4-year) predominantly baseflow regime. Paralleling changes in fish statistics have been notable changes in aquatic habitat. Both natural (hydrograph) and anthropogenic (fishery and grazing management) factors will be discussed as interdependent legislators of the short- and long-term sustainability of viable native fish populations in the upper Verde River.

03:45:00 PM 11/18/00 - Community structure and food web dynamics in Devils Hole, Nevada - Wilson, KP^*1; Blinn, DW¹; Threloff, D²; Herbst, D³  (1 Northern Arizona University, Department of Biology; 2 Death Valley National Park; 3 Sierra Nevada Aquatics Research Lab)

Estimates of allochthonous and autochthonous carbon mass were measured in Devils Hole, Nevada, to determine the seasonal importance of each in the diet of the endangered Devils Hole pupfish, Cyprinodon diabolis. Diet and stable isotope analyses were also employed to examine seasonal variability of carbon sources for C. diabolis. Solar energy was monitored continuously and litter traps (allochthonous input) were collected at 4 wk intervals for one year. Algal and invertebrate composition and biomass were measured at bimonthly intervals. Primary productivity and total ecosystem metabolism were also estimated at bimonthly intervals. Terrestrial plants made up approximately 57% of the allochthonous input during the year with the greatest input in December and April. Seasonal composition and biomass of autochthonous carbon is directly related to solar energy input. Daily light energy during the summer, with a maximum of 3 h of direct light, ranged from 200 mE*m-2 s-1 to 1350 mE*m-2 s-1 compared to a maximum of only 30 mE*m-2 s-1 during the winter when no direct light reached the system. Mean algal biomass in the summer was 24.50 g AFDM m2 (SE ±6.4) and composed of dense cyanobacterial mats and Spirogyra sp. filaments, while average winter biomass was 5.50 g AFDM m2 (±2.5) and composed largely of diatoms and Oscillatoria spp. Annual invertebrate biomass averaged 0.47 g AFDM m2 (±0.04) and was dominated by the snail Tryonia variegata. Diets of C. diabolis revealed large quantities of carbonate crystals, detritus, and diatoms. Gut content analysis also had small numbers of Stenelmis calida, Liodessus affinis, T. variegata, and Hyalella sp. in 30% of the fish examined. Preliminary multiple stable isotope analysis showed a depletion of d13C from October 1999 to February 2000. October values ranged from -28.5 to -24.5o/oo, while February values ranged from -29 to -31o/oo. This suggests C. diabolis utilizes different carbon sources during the year. The implications of the trophic status of the flatworm, Dugesia dorotocephala on the pupfish population will be discussed.

04:00:00 PM 11/18/00 - Ecology and status of Ash Meadows naucorid populations - Parker, MS^*1; Scoppettone, GG²; Neilsen, MB²  (1 Southern Oregon Universiy, Department of Biology; 2 US Geological Survey, Reno Field Station)

This study examined factors determining the distribution and abundance of two endemic species of creeping water bugs, Ambrysus amargosus and A. relictus (Heteroptera: Naucoridae), within and among thermal springs of the Ash Meadows National Wildlife Refuge. Specifically, we conducted field surveys and manipulative experiments to explore naucorid population dynamics, life histories, habitat associations, and feeding ecology. Our goal was to provide information useful in guiding efforts to restore severely altered spring habitats. Here we will summarize results of our two-year investigation and discuss them in the context of future restoration activities.

04:15:00 PM 11/18/00 - Desert fishes of the past: archaeological fish remains from Owens Valley, California - Butler, VL^*1; Delacorte, MG²  (1 Portland State University; 2 California State University, Sacramento)

Excavation of multiple archaeological sites in Owens Valley, California has provided a substantial assemblage of fish remains spanning much of the last 8000 years. Striking changes in taxonomic representation and body size are indicated. Large-bodied Catostomus fumeiventris (Owens sucker) dominates early sites that date before 4500 years ago; Gila bicolor (tui chub) and smaller Catostomus predominate in later sites that date to the last 500 years. Two main factors, environmental change and cultural use patterns, may account for these trends. The environmental explanation suggests that changes in extent and stability of aquatic habitat favored different fish taxa given differences in life history strategies. The cultural explanation holds that there was a wider expansion in resource use, leading to scheduling conflicts and shifts in fish use. These explanations are examined along with the difficulty of distinguishing environmental from cultural factors in accounting for change in the archaeological record.

04:30:00 PM 11/18/00 - Ash Meadows: a photographic perspective 1938-2000 - Webster, T^*1; Unmack, PJ  (1 Desert Springs Action Committee; 2 Arizona State University, Department of Biology)

Ash Meadows has played an important role in the conservation movement in the American West, especially in the formation of the Desert Fishes Council. This was due to it's permanent water supply in an otherwise parched landscape, which attracted the attention of ranching and housing developers who vastly modified the aquatic habitats. Fortunately, environmental concerns ruled the day and ultimately resulted in the formation of the Ash Meadows Wildlife Refuge. Due to the significance of the area and the interest in its conservation, many photographs exist from the late 1960's and early 1970's. Fewer photos exist prior to this time. Present efforts are focusing on locating additional photographs from all time periods, as it is difficult to get series of images suitable for comparison due to differences in photographic perspective. However there is sufficient documentation for a basic comparisons of changes from when Robert Rush Miller began his studies there in 1938. A major hiatus exists until the late 1960's when many students, professors and others involved with the "proto" Desert Fishes Council spent much time in the area, many of whom photographed habitats. Our own involvement in Ash Meadows began in 1994-5 and is continuing. Several springs have good series of photos that provide an indication of changes over time. These include Big, Jackrabbit, Kings Pool, Point of Rocks, Crystal, Longstreet, Rogers, and Fairbanks. These photographic comparisons allow both anthropomorphic and natural changes over time to be recorded. They also document nature's ability to recover from seemingly total devastation, both of which are useful in restoration efforts.

POSTER - Photophobic reactions in hydrobiid snails from the Owens Valley, California - Bowler, PA^*1  (1 University of California, Dept. of Ecology and Evolutionary Biology, and White Mountain Research Station, 3000 E. Line Street, Bishop, CA)

Photophobic sensitivity was examined in Pyrgulopsis wongi Hershler, P. perturbata Hershler, P. owensensis Hershler, and Tryonia protea (Gould, 1855) using ten minute exposures to sunlight and darkness on a circular grid indicating distance traveled for two groups of fifty snails per species at each locality. Some species from sites with no fish predators exhibited only a slight photophobic reaction (P. wongi and P. owensensis), while one taxon (P. perturbata) from a predator inhabited location (Fish Slough) showed rapid photophobic response. Tryonia protea from the predator rich Owens River had no reaction and is abundant at the locality sampled on both rock surfaces and aquatic vegetation during the daytime. Pyrgulopsis californiensis from the UC Natural Reserve System's Oasis de los Osos Reserve (San Bernardino County near Palm Springs) has no fish predators and was not photophobic in its responses. The light sensitive species congregated under rocks placed along the grid in addition to moving far greater distances in the light exposure treatments. The photophobic species had little movement in the dark, while the non-reactive species exhibited little movement at all, with distances similar in both light and darkness. A large population of Tryonia protea from the mainstem Owens River above Benton Crossing is reported, which is the only truly fluvial Hydrobiid known from the Owens Valley or of which the author is aware in the Great Basin.

POSTER - Feeding ecology and habitat of the threespine stickleback, {Gasterosteus} {aculeatus} {microcephalus}, in a threatened population of northwestern Baja California, México - Ruiz-Campos, G^*1; Sánchez-Gonzáles, S¹; Contreras-Balderas, S²  (1 Facultad de Ciencias, Universidad Autónoma de Baja California, Ensenada, B.C., México; 2 Bioconservación, A.C., San Nicolás de los Garza, N.L., México)

The feeding ecology and habitat of the threatened threespine stickleback ({Gasterosteus} {aculeatus}{microcephalus} Girard, 1854) were  monthly determined from November 1996 to May 1997 in  a mesohaline lagoon of northwestern Baja  California, México. The analysis of 179 stomach contents indicate basically a diet of microcarnivorous type, mainly composed of cyclopoid copepods (43.8%) and larvae of chironomids (39.1%). The diet in function of the size and sex of the fish was dominated by copepods in autumn and winter, and by larvae of chironomids during spring. Diet overlap (Schoener's index) was significant between size classes (I= 30-45 mm  standard length [SL] and II= 46-60 mm SL) and sexes of the fish. Individual trophic diversity was different along the study period, however, it was significantly similar (p< 0.05) with the size and sex of the fish. The average prey size consumed by the fish was independent of the size of its mouth. The feeding strategy of the threespine stickleback shifted from opportunist in winter to specialist in spring.

POSTER - Effect of introduced crayfish on growth of two native fishes of the Colorado River basin - Carpenter, J^*1; McIvor, CC¹  (1 US Geological Survey, Biological Resources Division)

The introduction of non-native organisms into aquatic ecosystems is considered a major factor in the decline of native fish in the west. Although crayfish are not native to the Colorado River basin, they are now found in portions of the mainstem and in many of its tributaries. The virile crayfish (Orconectes virilis), an aggressive polytrophic species, is the most common crayfish in the Colorado River basin. I conducted field and laboratory experiments to assess competition for food between virile crayfish and two native fishes: Gila chub (Gila intermedia) and flannelmouth sucker (Catostomus latipinnis). In Sabino Creek, Arizona, I manipulated crayfish densities in isolated pools to examine effects of crayfish on growth, mortality, and recruitment of Gila chub. Regardless of crayfish density, Gila chub declined slightly in weight and condition, and I observed no difference in mortality and recruitment as well. In the laboratory, I conducted density manipulation experiments to measure intra- and interspecific food competition between crayfish and the two fishes. Growth of Gila chub was less affected by competition with crayfish than by intraspecific competition. Thus both field and laboratory experiments indicate crayfish are not strong competitors with Gila chub for food. However, in the laboratory, growth of flannelmouth sucker was negatively impacted by presence of crayfish. These experiments provide evidence that introduced crayfish can reduce fish growth by competition for food, however native fishes differ in their vulnerability to crayfish competition.

POSTER - Temperature tolerances and habitat conditions for Bonneville cutthroat trout in the Thomas Fork of the Bear River, Wyoming. - Johnstone, H C^*1; Rahel, F J  (1 University of Wyoming, Department of Zoology and Physiology; 2 University of Wyoming, Department of Zoology and Physiology)

Bonneville cutthroat trout occupy only a fraction of their historical range, and some of the last remaining genetically pure populations are in the Thomas Fork of the Bear River, Wyoming.  The creeks in this drainage experience summer high water temperatures reported to be lethal to other trout.  Water temperatures and water quality were monitored in the Thomas Fork during summer of 1998 and 1999 to determine if conditions may be limiting to Bonneville cutthroat trout populations.  Daily maximum July-August water temperatures averaged 22.1oC, ranging from 17.6-25.0&#61616;C.  In the laboratory, the temperature lethal to 50% of the population during a 7 day constant exposure was 24.2oC.  However, when temperatures were cycled for 7 days and maximum temperatures were in the lethal range for only a few hours each day, fish did not die.  This temperature scenario simulates conditions observed in the field.  There were significant declines in activity and feeding from the control diel cycle (10-20oC) to the warm diel cycle (16-26oC), indicating sublethal effects of increased temperature.  Based on my field and laboratory results, I concluded that for the summer seasons of 1998 and 1999 water temperatures may have occasionally reached stressful levels in some streams but were not acutely lethal for Bonneville cutthroat trout in the Thomas Fork drainage.

POSTER - Bait and switch: attraction of tui chub to baited traps - Hartshorn, E^*1; Tobey, T N¹  (1 Bishop Union High School, CA)

We conducted an experiment out at the McNally ditch, a distributary of the Owens River, 3 miles north of the Laws Museum, (Inyo County, CA). The project was part of our Advanced Biology high school class. Our goal was to find a more effective way to trap hybrid tui chubs (Gila bicolor ssp.) to improve the information known today about the native tui chub (Gila bicolor snyderi). Other capture methods such as electrofishing have been a subject of debate because of the chance of injuries to the fish. We attempted to lure fish with everything from chocolate to cat food. We thought that they would be attracted to the smells of our concoctions but through our research we found that they were more lured to the traps that had no bait at all (p<0.01). Perhaps these small minnows have a bigger brain and a smaller nose than we thought.