Proceedings of the

Desert Fishes Council

 

VOLUME XXXIII

 

2001 ANNUAL SYMPOSIUM

15 ‑ 18 November

Sul Ross State University

Alpine, Texas U.S.A.

Edited by

 

Dean A. Hendrickson

Texas Natural History Collection

University of Texas at Austin

10100 Burnet Road, PRC 176 / R4000

Austin, Texas 78758-4445, U.S.A.

 

and

 

Lloyd T. Findley

Centro de Investigación en Alimentación y Desarrollo, A.C.-Unidad Guaymas

Carretera al Varadero Nacional Km. 6.6, “Las Playitas”

Apartado Postal 284, Guaymas, Sonora 85400, MÉXICO

 

published: December 15, 2002 ISSN 1068-0381

P.O. Box 337 u Bishop, California 93515-0337 u 760-872-8751 Voice & Fax u e-mail: phil at desertfishes dot org


 

 

MISSION / MISIÓN

The mission of the Desert Fishes Council is to preserve the biological integrity of desert aquatic ecosystems and their associated life forms, to hold symposia to report related research and management endeavors, and to effect rapid dissemination of information concerning activities of the Council and its members.

OFFICERS / OFICIALES

President: David L. Propst, Conservation Services División, New Mexico Department of Game and Fish, Santa Fe, NM 87504

Immediate Past President: Gary P. Garrett

Executive Secretary: E. Phil Pister, P.O. Box 337, Bishop, California 93515-0337

COMMITTEES / COMITÉS

Executive Committee: Michael E. Douglas, Gary P. Garrett, Dean A. Hendrickson, Nadine Kanim, Paul C. Marsh, E. Phil Pister, David L. Propst

Area Coordinator: Nadine Kanim

Awards: Astrid Kodric Brown

Membership: Paul C. Marsh

Proceedings Co-Editors: Lloyd T. Findley and Dean A. Hendrickson

Proceedings Translation: Miguel Á. Cisneros, Lloyd T. Findley and Gabriela Montemayor

Program: Michael E. Douglas (Chair), Dean A. Hendrickson, Nadine Kanim

Webmasters: Dean A. Hendrickson and Peter Unmack

Local Committee: Nathan Allan and Chris Hoagstrom

MEMBERSHIP / MEMBRESÍA

Membership in the Desert Fishes Council is open to any person or organization interested in or engaged in the management, protection, or scientific study of desert fishes, or some related phase of desert fish conservation. Membership includes subscription to the Proceedings of the Desert Fishes Council. Annual dues are $25 (regular: domestic or foreign), $15 (student), $35 (family: 1 Proceedings), >$35 (sustaining), $650 (life, single payment), and $1,000 (patron: single payment). Membership applications are available on the website (below). Send dues payments and general contributions along with address information (including affiliation, voice, fax, and e‑mail) and indication of permission to include this information in a published directory of the Desert Fishes Council to:Jerry Stefferud, Membership Chair, 315 East Medlock Drive, Phoenix, AZ 85012, 602-274-5544, email: dfc-membership_at_cox.net. Membership applications are found at the end of this volume and online payment of dues using PayPal is available on the DFC website.

ABOUT THE PROCEEDINGS OF THE DESERT FISHES COUNCIL / SOBRE LOS PROCEDIMIENTOS DEL CONSEJO DE LOS PECES DEL DESIERTO

It is the policy of the Council to select and publish in the annual Proceedings of the Desert Fishes Council abstracts, discussion summaries, business items, resolutions, and other material submitted and presented at the Annual Symposium. All contributions are subject to editorial review and are published following technical editing and automated electronic processing to standardize format. Resolutions are published exactly as passed by the membership in the business meeting of the Annual Symposium. The Proceedings Translation Committee provides original translations of abstracts in English when translations are not provided by authors, and edits all Spanish abstracts provided by authors. The Translation Committee reserves the right to edit abstracts in one language to improve grammar and clarity before translating to the other language, but accepts full responsibility for errors in translations for abstracts they translate. The Proceedings are published and delivered to all members of the Desert Fishes Council and subscribing libraries in the year following the Annual Symposium.

 

The Council offers extensive information on the World Wide Web about itself and the organisms and ecosystems it strives to protect:

 

http://www.desertfishes.org

 

Permission to utilize copyrighted artwork on the cover was granted by University of Arizona Press and the artist, Barbara Terkanian.

 

 

 

 

 

 

 

 

ISSN 1068-0381                                                                                                          The entire DFC Proceedings is printed on recycled paper


TABLE OF CONTENTS / TABLA DE CONTENIDOS

MISSION / MISIÓN.. i

OFFICERS / OFICIALES. i

COMMITTEES / COMITÉS. i

MEMBERSHIP / MEMBRESÍA.. i

ABOUT THE PROCEEDINGS OF THE DESERT FISHES COUNCIL / SOBRE LOS PROCEDIMIENTOS DEL CONSEJO DE LOS PECES DEL DESIERTO.. i

Abstracts in Alphabetical Order (First Author) / Resumenes en Orden Alfabetico (Primer Autor). 1

Abate, PD; Holden, PB; Welker, TL.. 1

Razorback sucker, Xyrauchen texanus, studies on Lake Mead, Nevada and Arizona, 2000-2001. 1

Estudios sobre matalote jorobado, Xyrauchen texanus, en el Lago Mead, Nevada y Arizona, 2000-2001. 1

Aló, D; Turner, TF. 2

Genetic diversity and effective population size of endangered Río Grande silvery minnow: implications for species recovery. 2

Diversidad genética y tamaño efectivo poblacional de la carpa chamizal (especie en peligro): implicaciones para su recuperación. 3

Allan, NL.. 3

Conservation of threatened and endangered fishes of western Texas. 3

Conservación de peces amenazados y en peligro del occidente de Texas. 3

Andersen, ME.. 4

Bonneville Basin area report 4

Informe del área de la Cuenca de Bonneville. 4

Blasius, HB.. 5

Chemical removal of green sunfish, Lepomis cyanellus, from Sabino Creek, Arizona. 5

Remoción química del pez sol, Lepomis cyanellus, del Arroyo Sabino, Arizona. 5

Brooks, J1; Propst, D2; Hoagstrom, C1; Platania, S3; Turner, T3; Wiley, B4. 6

Native fish research and management in the upper/middle Rio Grande basin during 2001. 6

Investigación y manejo de peces nativos en las partes alta y media de la cuenca del Río Bravo (Rio Grande) durante 2001. 6

Camarena-Rosales, F1; Ruíz-Campos, G1; Varela-Romero, A2; Sánchez-González, S3; De la Rosa-Vélez, J4. 7

Preliminary aspects of genetic and morphological variation of native trouts from northwestern México. 7

Aspectos preliminares sobre variabilidad genética y morfológica de las truchas nativas del noroeste de México. 8

Carson, EW... 8

Relationship between genetic and environmental variation within a region of contemporary hybridization between two pupfishes endemic to Cuatro Ciénegas, Mexico. 8

Relación entre variabilidad genética y ambiental en una región de hibridación contemporánea entre dos especies de peces cachorritos endémicos de Cuatro Ciénegas, México. 8

Chart, T1; Mueller, G2; Pfeifer, F3; Modde, T3; Andersen, ME4. 9

Area report: upper Colorado River basin. 9

Informe de la cuenca alta del Río Colorado. 10

Cohen, AE1; Hendrickson, DA1; Marks, JC2. 11

Cuatro Ciénegas yesterday and today: a look at historic and modern photographs. 11

Cuatro Ciénegas ayer y hoy: una mirada a fotografías históricas y modernas. 11

Cohen, K1; Hendrickson, DA2; Hulsey, DH3. 11

Investigation of oral jaw polymorphism and functional morphology in Herichthys minckleyi (Cichlidae). 11

Investigación del polimorfismo bucal y morfología funcional en Herichthys minckleyi (Cichlidae). 12

Collyer, ML1; Novak, J2; Stockwell, CA1. 12

Analysis of morphological variation among White Sands pupfish, Cyprinodon tularosa, populations using geometric morphometric techniques. 12

Analisis de la variación morfológica entre poblaciones del cachorrito de White Sands, Cyprinodon tularosa, por medio de técnicas de morfometría geométrica. 13

Connor, PJ1; Hardy, TB2; Bartsch, NR2. 14

Assessment of the springflow and instream flow requirements of the fountain darter in Comal and San Marcos springs, Texas. 14

Evaluación de requerimientos de flujos de manantial y de canales para la perca de manantial en Comal y San Marcos, Texas. 14

Contreras Balderas, S1; Lozano Vilano, ML2; García Ramírez, ME2. 15

Indices of biological and bioecological integrity in the lower Río Bravo/Rio Grande, Mexico. 15

Indices de integridad biológica y bio-ecológica en la parte baja del Río Bravo/Rio Grande, México. 15

Contreras Balderas, S1; Lozano Vilano, ML2; García Ramírez, ME2. 15

Index of Biological Integrity: historical version for the Río Sabinas, Coahuila, Mexico. 15

Índice de Integridad Biológica: versión histórica para el Río Sabinas, Coahuila, México. 16

Contreras Balderas, S. 16

Northeast México Area Coordinator report 16

Informe del coordinador del Área Noreste de México. 16

Cook, AE1; Martinez, CT2; Clemmer, G5; Goochild, S2; Heinrich, JE1; Scoppettone, GG3; Sevon, M1; St George, D4. 17

Nevada area report 17

Informe del área de Nevada. 19

Davenport, SR1; Smith, JR1; Altenbach, CS2. 20

Propagation of Rio Grande silvery minnow, Hybognathus amarus. 20

Propagación de la carpa Chamizal, Hybognathus amarus. 21

Douglas, ME1; Douglas, MR2. 21

Biodiversity of catostomids in Arizona with emphasis on the Little Colorado River form.. 21

Biodiversidad de catostómidos en Arizona, con énfasis en la forma del Río Little Colorado. 21

Douglas, MR1; Douglas, ME2. 22

Genetic variation in speckled dace, Rhinichthys osculus, from the Colorado River basin. 22

Variación genética en la carpita pinta, Rhinichthys osculus, de la cuenca del Río Colorado. 22

Dowling, TE1; Kelsen, AT1; Markle, DF2. 23

Mitochondrial DNA variation among year classes of endangered suckers of Klamath Lake, Oregon. 23

Variación del ADN mitocondrial entre clases anuales de matalotes en peligro, en el Lago Klamath, Oregon. 23

Dudley, RK; Platania, SP.. 23

Downstream transport rates of passively drifting particles and larval Colorado pikeminnow, Ptychocheilus lucius, in the San Juan River. 23

Tasas de transporte río-abajo de partículas inertes a la deriva y de larvas de carpa gigante del Colorado, Ptychocheilus lucius, en el Río San Juan. 24

Echelle, AA1; Echelle, AF1; Contreras Balderas, S2; Lozano Vilano, ML3. 24

Pupfishes of the northern Chihuahuan Desert: perspectives on their conservation. 24

Peces cachorrito del norte del Desierto de Chihuahua: perspectivas sobre su conservación. 24

Edwards, RJ1; Garrett, GP2; Marsh-Matthews, E3. 25

Fish communities inhabiting the Río Conchos basin and middle Río Bravo/Rio Grande, Mexico and U.S.A., with emphasis on conservation and status. 25

Comunidades de peces de la cuenca del Río Conchos y la parte media del Río Bravo/Rio Grande, México y E.U.A., con énfasis en su conservación y estatus. 25

Garrett, GP.. 25

Innovative approaches to recover endangered species. 25

Enfoques novedosos para recuperar especies en peligro. 26

Garrett, GP1; Edwards, RJ2; Allan, NL3. 26

Desert fishes research and management in Texas during 2001. 26

Investigación y manejo de peces del desierto en Texas durante 2001. 27

Golden, ME1; Holden, PB1; Heinrich, J2. 27

Effect of mechanical removal of nonnative red shiner, Cyprinella lutrensis, on re-establishment of endangered woundfin, Plagopterus argentissimus, in the Virgin River, Nevada and Arizona. 27

Efecto de la remoción mecánica de la carpita roja no nativa, Cyprinella lutrensis, en el restablecimiento de la carpita afilada (en peligro), Plagopterus argentissimus, en el Río Virgin, Nevada y Arizona. 28

Harstad, DL; Stockwell, CA.. 30

Costs of parasitism (Diplostomatidae) to male White Sands pupfish, Cyprinodon tularosa. 30

Costos del parasitismo (Diplostomatidae) para los machos del cachorrito de White Sands, Cyprinodon tularosa. 30

Heinrich, JE; Grode, JR.. 30

Abundance of Moapa White River springfish, Crenichthys baileyi moapae, in the Muddy River, with recent surveys of other Muddy River native fishes. 30

Abundancia del pez de manantial Moapa del Río White, Crenichthys baileyi moapae, en el Río Muddy, con levantamientos recientes de otros peces nativos del Río Muddy. 31

Hendrickson, DA1; Cohen, AE2; Hulsey, D3; Marks, JC4. 31

Detailed studies of the Herichthys minckleyi (Cichlidae) population in the Poza Escobedo system, Cuatro Ciénegas, Coahuila, México: its relationship with snails (Mexipyrgus carranzae) and temperature, and notes on other biota. 31

Estudios detallados de la población de Herichthys minckleyi (Cichlidae) en el sistema de la Poza Escobedo, Cuatro Ciénegas, Coahuila, México: su relación con los caracoles (Mexipyrgus carranzae) y temperatura, con notas sobre otros organismos. 32

Hoagstrom, CW... 32

Historical and recent distributions of lower Pecos River fishes. 32

Distribuciones histórica y reciente de peces de la parte baja del Río Pecos. 32

Howells, RG.. 33

Declining status of freshwater mussels in the Rio Grande/Río Bravo, with comments on other bivalves. 33

Estatus de descenso de mejillones de agua dulce en el Río Bravo/Rio Grande, con notas sobre otros bivalvos. 33

Hubbs, C.. 34

Environmental causes for endemism in the Chihuahuan Desert, with examples from Gambusia. 34

Factores ambientales causantes del endemismo en el Desierto de Chihuahua, con ejemplos de Gambusia. 34

Hulsey, CD1; Hendrickson, DA2; Marks, JC3. 34

Ontogeny of feeding and functional morphology of Herichthys minckleyi 34

Ontogenia de la morfología alimenticia y funcional de Herichthys minckleyi 35

Karges, JP.. 35

Aquatic conservation and The Nature Conservancy in West Texas. 35

Conservación acuática y The Nature Conservancy en Texas Occidental 35

Kepner, WG1; Baker, JR2; Peck, DV3; Kaufmann, PR3; Hughes, RM4; Kinney, WL2; Chaloud, DJ1; Jones, KB1. 36

Aquatic stream indicator development in the western United States: preliminary results for Arizona, Nevada, and Utah. 36

Desarrollo de indicadores acuáticos para arroyos del occidente de EUA: resultados preliminares para Arizona, Nevada, y Utah. 36

Kitcheyan, DC; Modde, T. 37

Small-scale movement patterns of Colorado pikeminnow in regulated tributaries of the Green River. 37

Patrones de movimiento a pequeña escala de la carpa gigante del Colorado en tributarios controlados del Río Green. 37

Kloeppel, HM1; Marks, JC1; Hendrickson, DA2. 38

Interactions of an endemic snail and fish: negative effects of molluscivore presence on snail density. 38

Interacciones de un caracol y un pez endémicos: efectos negativos de depredadores de moluscos en la densidad de caracoles. 38

Kodric-Brown, A; Rosenfield, J. 38

Tempo and mode of hybridization: differences in competitive ability between populations of Pecos pupfish. 38

Tasa y forma de hibridación: diferencias en la habilidad competitiva entre poblaciones del cachorrito del Pecos. 39

Lang, BK1; Gervasio, V2; Berg, D2; Guttman, S2; Allan, NL3; Gordon, ME4. 39

Gammarid amphipods of northern Chihuahuan Desert spring systems: an imperiled fauna. 39

Anfípodos gamáridos de los sistemas de manantial del norte del Desierto de Chihuahua: una fauna amenazada. 39

Lema, SC; Watters, JV; Nevitt, GA.. 40

Considering alternative reproductive phenotypes in habitat and species restoration. 40

Consideración de fenotipos reproductivos alternativos para la restauración de hábitat y de especies. 40

McPhee, MV.. 41

Mechanisms of displacement of Rio Grande sucker by white sucker in the upper Rio Grande/Río Bravo. 41

Mecanismos de desplazamiento del matalote del Bravo por el matalote blanco en la parte alta del Río Bravo/Rio Grande. 41

Minckley, CO1; Gobalet, KW2; Hardin, K2. 41

Report on a collection of fish remains from the Little Colorado River canyon, Arizona. 41

Reporte de una colección de restos de peces del cañón del Río Little Colorado, Arizona. 42

Modde, T; Kitcheyan, C.. 42

Seasonal movement patterns of Colorado pikeminnow in regulated tributaries of the Green River subbasin. 42

Patrones de movimiento estacional de la carpa gigante del Colorado en tributarios controlados de la subcuenca del Río Green. 42

Mueller, G1; Marsh, P2. 43

Lost, a desert river and its native fishes: A historical perspective of the lower Colorado River. 43

Pérdida de un río del desierto y de sus peces nativos: Perspectiva histórica de la parte baja del Río Colorado. 43

Norris, SM1; Fischer, JM1; Minckley, WL2. 44

Are the world's fish faunas well known?: A preliminary examination of Gila from northwestern Mexico. 44

¿Son bien conocidas las ictiofaunas del mundo? Un análisis preliminar del género Gila del noroeste de México. 44

Parmenter, SC1; Becker, D1; Keeney, S1; Miller, R1; Millosovich, J1; Penix, S2; Russi, R3. 44

2001 California area report 44

Reporte 2001 del área de California. 46

Perkins-Keleher, MJ. 48

Bioassessments and determining the ecological integrity of Utah's desert wetlands. 48

Bio-evaluaciones y determinación de la integridad ecológica de los humedales desérticos de Utah. 49

Platania, SP.. 49

Fishes of the Rio Grande/Río Bravo in the northern Chihuahuan Desert 49

Peces del Río Bravo/Rio Grande en la parte norte del Desierto de Chihuahua. 50

Propst, DL1; Platania, SP2; Gottlieb, SJ2. 50

Preparation of a new, multimedia book on New Mexico fishes. 50

Preparación de un nuevo libro multimedia sobre peces de Nuevo México. 50

Reid, S1; Munhall, A2; White, R3; Allen, C3; Tinniswood, B4; Edwards, C4; Smith, R4; Chappell, P5. 51

Area report: Extreme northwestern Great Basin (Oregon and northeastern California). 51

Informe de área: Extremo noroeste de la Gran Cuenca (Oregon y noreste de California). 51

Reid, SB1; Kettratad, J2. 51

Modoc sucker -- the hybridization threat, fact or fiction?. 51

Matalote Modoc -- la amenaza de hibridación: ¿realidad o ficción?. 52

Remshardt, WJ; Watts, HE.. 52

Habitat use by an assemblage of fishes in the middle Rio Grande/Río Bravo, New Mexico. 52

Uso de hábitat por un conjunto de peces en la parte media del Río Bravo/Rio Grande, Nuevo México. 52

Rissler, PH; Scoppettone, GG.. 52

Population viability analysis of Independence Lake Lahontan cutthroat trout 52

Análisis de viabilidad de la población de trucha degollada de Lahontan del Lago Independence. 53

Robertson, MS1; Oborny, EO1; Arsuffi, TL2; Groeger, AG2; Hall, R3. 53

Variable flows and biodiversity associated with high-volume springs of the Edwards Plateau, Texas. 53

Flujos variables y biodiversidad relacionada a manantiales grandes de la Planicie Edwards, Texas. 53

Rogowski, DL; Stockwell, CA.. 54

Indirect effects of snail distribution on the White Sands pupfish, Cyprinodon tularosa. 54

Efectos indirectos de la distribución de caracoles sobre el cachorrito de White Sands, Cyprinodon tularosa. 54

Rosenfield, JA; Kodric-Brown, A.. 55

Population structure effects on rate of introgression between sheepshead minnow and Pecos pupfish. 55

Efectos de la estructura poblacional en la tasa de introgresión entre el bolín y el cachorrito del Pecos. 55

Ross, ST1; Modde, TC2. 56

Age determination and life history aspects of roundtail chub, Gila robusta (Cyprinidae), in the Yampa River canyon, Colorado. 56

Determinación de edad y aspectos del ciclo de vida de la carpa cola redonda, Gila robusta (Cyprinidae), en el cañón del Río Yampa, Colorado. 56

Schmidt, JC1; Everitt, BL2; Richard, GA3. 57

Hydrology, geomorphology, and transformation of the Rio Grande/Río Bravo. 57

Hidrología, morfología y transformación del Río Bravo/Rio Grande. 57

Schwemm, MR; Unmack, PJ. 58

Native catostomids as prey of introduced largemouth bass in a central Arizona stream.. 58

Catostómidos nativos como presas de la lobina negra introducida en un arroyo del centro de Arizona. 58

Scudday, JF. 58

My favorite fishing holes in west Texas: where did they go?. 58

Mis pozas de pesca favoritas en el oeste de Texas: ¿a dónde se fueron?. 58

Sharp, JM Jr.1; Boghici, R2; Uliana, MM3. 59

Groundwater systems feeding springs of northern Trans-Pecos, Texas. 59

Sistemas de agua subsuperficial que abastecen los manantiales del norte del sistema Trans-Pecos, Texas. 59

Stefferud, JA1; Propst, DL2. 59

Assemblages of fishes in the Guzmán Basin, Chihuahua, Mexico. 59

Conjuntos de peces en la Cuenca Guzmán, Chihuahua, México. 60

Stefferud, JA1; Bettaso, R2; Voeltz, J2; Gurtin, S2; Blasius, H2; Stefferud, S3; Marsh, P4; Sjoberg, J5. 60

Lower Colorado River area report 60

Reporte de área de la parte baja del Río Colorado. 62

Stefferud, SE1; Stefferud, JA2. 63

Can conservation be achieved through Section 7 of the Endangered Species Act?: Gila topminnow in Redrock Canyon, Arizona -- a case study. 63

¿Puede lograrse la conservación mediante la Sección 7 de la Ley de Especies en Peligro? El guatopote del Gila en el Cañón Redrock, Arizona: un estudio de caso. 64

Stephens, MJ1; Hendrickson, DA2; Arsuffi, TA1. 65

Heredity of trophic polymorphism of an endangered Mexican cichlid fish, Herichthys minckleyi 65

Transmisión por herencia del polimorfismo trófico de un pez cíclido mexicano en peligro, Herichthys minckleyi 65

Swanson, BO1; Gibb, AC1; Marks, JC1; Hendrickson, DA2; Williamson, C1. 65

Intraspecific competition in a polymorphic cichlid, Herichthys minckleyi: Does variation in jaw morphology lead to resource partitioning?. 65

Competencia intraespecífica en un cíclido polimórfico, Herichthys minckleyi: ¿Conlleva a la repartición de recursos la morfología de la mandíbula?. 66

Tech, CL.. 66

Reproductive behavior of Comanche Springs and Leon Springs pupfishes. 66

Conducta reproductiva del cachorrito de Manantiales Comanche y del cachorrito de Manantiales León. 67

Thomas, C1; Bonner, TH1; Garrett, GP2; Arsuffi, TL1. 67

Effects of Micropterus dolomieu on habitat selection of fishes from Devils River, Texas. 67

Efectos de Micropterus dolomieu en la elección de hábitat de peces del Río Devils, Texas. 67

Urbanczyk, KM... 68

Contemporary water supply and availability in the northern Chihuahuan Desert 68

Abasto actual y disponibilidad de agua en la parte norte del Desierto de Chihuahua. 68

Varela-Romero, A1; Ruíz-Campos, G2; Camarena-Rosales, F2; Sánchez-González, S3; de la Rosa-Velez, J4; Villareal-Lizarraga, A5. 69

Study and conservation of native fishes in northwestern México: review for year 2001. 69

Estudio y conservación de peces nativos en la región noroeste de México: reseña para el año 2001. 69

Wares, JP; Turner, TF. 70

Conservation genetics of native southwestern U.S. trouts. 70

Genética de la conservación de las truchas nativas del suroeste de EUA.. 70

Williamson, CA1; Hendrickson, DA2; Marks, JC1. 70

Competitive interactions between invasive and endemic cichlids in Cuatro Ciénegas, México: evidence from stable isotopes and field experiments. 70

Interacciones de competencia entre cíclidos invasores y endémicos en Cuatro Ciénegas, México: evidencia a partir de isótopos estables y experimentos de campo. 70

MINUTES OF THE BUSINESS MEETING / MINUTAS DE LA REUNION DE NEGOCIOS. 72

DFC Hydrologic Basin and Agency Report Coordinators. 75

DESERT FISHES COUNCIL MEMBERSHIP.. 76

MEMBRESIA EN EL CONSEJO DE LOS PECES DEL DESIERTO.. 77

 


Abstracts in Alphabetical Order (First Author) / Resumenes en Orden Alfabetico (Primer Autor)

Abate, PD; Holden, PB; Welker, TL

(BIO-WEST, Inc., Logan, Utah)

Razorback sucker, Xyrauchen texanus, studies on Lake Mead, Nevada and Arizona, 2000-2001

Abstract

Southern Nevada Water Authority and the Colorado River Commission of Nevada, in cooperation with BIO-WEST, Inc. (B-W) and Nevada Division of Wildlife initiated a cooperative razorback sucker, Xyrauchen texanus, study on Lake Mead in 1996 to gather more information regarding population size, recruitment potential, and general life history. Other agencies joining as cooperators at the beginning of the study included United States Bureau of Reclamation (BOR), U.S. Fish and Wildlife Service (USFWS), and National Park Service. In 1998, BOR agreed to contribute additional funding to search for unknown populations of razorback sucker within the lake and for intensifying sampling efforts for juvenile razorback sucker.

Research activities for the 2000-2001 study year focused on the Echo Bay and Las Vegas Bay study sites, and the Colorado River inflow and the Grand Wash Bay areas. Larval sampling at standardized sites was continued at Echo and Las Vegas bays, and area-wide larval sampling was continued at the Colorado River inflow area and Grand Wash Bay. Development and use of a non-lethal aging technique and monitoring at the two population centers at Echo and Las Vegas bays were continued.

Monitoring of populations at Echo and Las Vegas bays determined that they continued to show high rates of growth compared to other wild razorback sucker populations. Growth of razorback sucker recaptured in the fifth year was 20.1 mm per year for those captured at Echo Bay, and 9.1 mm per year for those captured at Las Vegas Bay. Additionally, both populations successfully produced larvae which were collected throughout the February-May 2001 spawning season. Total number of larvae collected at the Echo Bay study site was second highest for the five study years, and the total number collected at Las Vegas Bay was similar to past study years. Two juveniles were captured at Las Vegas Bay; one was processed by USFWS, and one had a fin-ray section removed by B-W for aging. Aging methods were refined from the previous year to incorporate a less intrusive fin-ray section removal method and the use of a low-speed saw to more quickly and accurately process the sections for aging. In total, seven adults and one juvenile were aged during the fifth study year. Although final age estimations were pending at the time of this writing, approximate ages were 3 years for the juvenile, and 6 to 14 years for the adults.

Research activities at the Colorado River inflow and