Catostomus warnerensis abstract

Threatened fishes of the world: Catostomus warnerensis Snyder, 1908 (Catostomidae).

From

Williams, J.E. in press. Threatened fishes of the world: Catostomus warnerensis Snyder, 1908 (Catostomidae). Environmental Biology of Fishes :

Common names

Warner sucker (preferred), redhorse.

Conservation status

Endangered (IUCN red list), Threatened (U.S. Endangered Species Act).

Identification

A moderately-large catostomid (maximum 407 mm SL), D 9-12, A 7-81 P 14-17, V 9-11, LL 73-83. The dark upper sides and back are sharply separated from the creamy-white belly and lower sides. Spawning males and some females with brilliant red intermingled with the dark pigment of the sides. Other distinguishing characteristics include a large fronto-parietal fontanelle and small eyes.

Distribution

Endemic to Warner Basin, Oregon and Nevada. Range includes the permanent lakes in the valley (Hart, Crump and Pelican), ephemeral lakes, sloughs, and lower-gradient streams, White et al (1991) recently documented the sucker from Twelvemile Creek, Nevada, a small tributary of the Warner Basin.

Abundance

Historically abundant and widely-distributed in the basin, the Warner sucker still maintains sizable numbers in few habitats. An aggregation (spawning run?) of Warner suckers in a canal north of Hart Lake was estimated at 1,316 individuals during 1979 (Coombs et al 1979). In most habitats. the Warner sucker is rare, although aggregations of spawning adults or young-of-the-year may be encountered. Warner suckers comprised 2.5% of fishes collected in basin-wide 1987-89 surveys (Williams et al 1990). The larger of the remaining populations in Hart and Crump lakes, typically threatened by normative fishes, also faced severe drought during the past few years.

Habitat and Ecology

The species commonly occurred in the large, shallow natural lakes of the valley, spreading into sloughs and ephemeral lakes during wet years. Spawning runs occur in the spring as lake-dwelling fish move into tributary streams. Resident stream fish also are present in low-gradient streams. In lake habitats, individuals may live 20 years (White et al 1991). Reproduction: Spawning occurs primarily in the Honey and Twentymile creek systems, but also in canals (Williams et al 1990) and along the wave-swept lake shorelines (White et al 1991). In April 1989, spawning occurred in Honey Creek within 0.5 km of Hart Lake, and in May, in the canal north of the lake (Williams et al 1990). These are remnants of large, springtime runs of "redhorse" that were common prior to the 1940's.

Threats

Numerous small, agricultural diversion dams on creeks reduce stream flows and prevent migrations of adults and young. In lake habitats, normative brown bullhead, Ictalurus nebulosus, and crappie, Pomoxis spp., are abundant. The crappie are presumed predators on young suckers. During the late 1980's to present, drought has threatened remaining fish.

Conservation Actions

Studies conducted in 1979 (Coombs et al 1979), 1987-89 (Williams et al 1990), and 1991 (White et al 1991) have monitored changing conditions, determined threats, and established recovery strategies. Completed actions include fencing of streams to restore riparian vegetation, acquisition of ephemeral lake habitat, and construction of a fishway for passage over a diversion dam on Twentymile Creek. Drought conditions during 1991 prompted transplant of 80 adults to nearby Summer Lake Wildlife Management Area (White et al 1991).

Conservation Recommendations

Additional relocation efforts may be necessary if the drought continues. Drought conditions also may create opportunities to control normative fishes. Efforts to facilitate free movement of fish between lakes and spawning areas should be expanded. This may include construction of additional fishways, removal of deteriorating dams, and restoration of natural stream channels.

Remarks

Many of the above conservation actions also benefit the increasingly-rare native redband trout, Oncorhynchus mykiss ssp. Continuing drought during 1992 has dried "permanent" lakes, such as Hart and Crump, for the first time since the 1930's, highlighting the importance of preserving diverse habitat types.

References

Coombs, C. I., C. E. Bond & S. F. Drohan. 1979. Spawning and early life history of the Warner sucker (Catostomus warnerensis). Report to U.S. Fish and Wildlife Service, Sacramento, California. 52 pp.

Snyder, J. O. 1908. Relationships of the fish fauna of the lakes of southeastern Oregon. Bulletin of the Bureau of Fisheries. 28(for 1907):69-102.

White, R. K., T. L. Ramsey, M. A. Stern & A. V. Munhall. 1991. Salvage operations and investigations of the range and stream habitat characteristics of the Warner sucker, (Catostomus warnerensis), during spring and summer 1991. Oregon Natural Heritage Program, Portland. 44 pp.

Williams, J. E., M. A. Stern, A. V. Munhall & G. A. Anderson. 1990. Conservation status of threatened fishes in Warner Basin, Oregon. Great Basin Naturalist. 50:243-248.

Preparator

Jack E, Williams, Division of Wildlife and Fisheries, Bureau of Land Management, Department of the Interior, Washington D.C. 20240, U.S.A.

DFC	Home	Search	Species Index		Area Index	What's New	Comment
(Dean Hendrickson)				General information: (E. Phil Pister)