Threatened fishes of the world: Empetrichthys latos Miller, 1948 (Cyprinodontidae).

From

Williams, J. E. in press. Threatened fishes of the world: Empetrichthys latos Miller, 1948 (Cyprinodontidae). Environmental Biology of Fishes :

Common names

Pahrump poolfish (preferred), Pahrump killifish

Conservation status

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

Identification

A small, relatively-slender fish (maximum 70 mm SL), D 10-13, A 10-14, P 15-20F C 16-23, LL 29-33, pelvics lacking. Dorsal and anal fins set far back on body. Head is dorsoventrally depressed with broad mouth. Jaws unequal, with lower projecting ahead of upper.

Distribution

Three described subspecies, all endemic to springs in Pahrump Valley, Nevada, U.S.A. Empetrichthys 1. latos from a single spring on Manse Ranch, E. 1. pahrump (extinct) from 2 springs on Pahrump Ranch, and E. 1. concavus (extinct) from 1 spring on Raycraft Ranch (Miller 1948).

Abundance

Only remaining form, E. 1. latos, persists at 3 introduction sites in Nevada: Corn Creek. Spring Mountain Ranch State Park, and Shoshone Ponds, Sjoberg (1991) estimated total abundance of these populations at 24,800 in 1989. Fish is extirpated from historic locality on Manse Ranch. Habitat and ecology: The species occupied all available habitat in the spring pools and associated marshes in Pahrump Valley, where it is the only native fish. The spring at Manse Ranch was approximately 15 m wide x 18 m long and 2 m deep. Its water was crystal clear and its temperature of 24°C was constant. Poolfish are omnivorous, feeding on a wide variety of animal and plant matter.

Reproduction

Spawning peaks in spring, but may occur in any season if proper conditions are present.

Threats

The spring at Manse Ranch dried in 1975 because of excessive pumping of groundwater for agricultural development. Other springs containing poolfish in Pahrump Valley were filled or pumped dry in the 1950's and 1960's (Miller et al 1989). Prior to loss of spring habitats, poolfish populations had been reduced by introductions of carp and bullfrogs. Introduced populations are threatened by encroaching vegetation in the shallow ponds and the introduction of bullfrogs and other normative species.

Conservation action

Pahrump poolfish were first transplanted from Manse Ranch in 1970 and now occur in 3 relatively secure locations outside of their native range. The introduction sites are semi-natural but require periodic maintenance to control vegetation and to provide sufficient water supplies.

Conservation recommendations

The species cannot be considered to be recovered until a secure population is reestablished in its native habitat. Manse Ranch should be acquired by a conservation organization or Federal agency and its spring system restored. Close monitoring of introduced populations is required to determine population trends and control introductions of nonnative species. The recovery plan for the species (U.S. Fish and Wildlife Service 1980) also calls for further studies on the biology and habitat requirements.

Remarks

The only other species in the genus, E. merriami, became extinct in the early 1950's (Miller et al 1989). leaving E. 1. latos as the only surviving member of this genus.

References

Miller, R. R. 1948. The cyprinodont fishes of the Death Valley system of eastern California and southwestern Nevada. Miscellaneous Publications of the Museum of Zoology, University of Michigan. 68:1-155.

Miller, R. R.., J. D. Williams, & J. E. Williams, 1989. Extinctions of North American fishes during the past century. Fisheries (Bethesda). 14(6):22-38.

Sjoberg, J. 1991. Nevada Department of Wildlife Endemic Fish Program status report - 1989. Proceedings of the Desert Fishes Council. 21:241-244.

U.S. Fish and Wildlife Service, 1980. Pahrump killifish recovery plan. U.S. Fish and Wildlife Service, Portland, Oregon. 30 pp.

Preparator

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

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