Pahrump Poolfish

Empetrichthys latos latos

Description

The Pahrump poolfish, Empetrichthys latos latos, is a slender fish, reaching a length of 3 in (8 cm). It has a broad mouth, a short and slender head, and no pelvic fins. Both sexes are greenish above and silvery green below. During spawning season males appear lightly washed with blue. The Pahrump poolfish is the only surviving species in the genus Empetrichthys, following the extinction in the late 1940s of the Ash Meadows killifish (E. merriami ). The Pahrump poolfish is also called the Pahrump killifish.

Behavior

Young Pahrump poolfish are more active during daylight while adults are more active at night. Peak spawning occurs in the spring, although different groups will spawn throughout the year. During her breeding cycle, the female seeks seclusion for egg-laying in remote corners of the springs. The fry remain near the bottom or in areas that offer protection from predation. This fish is omnivorous and eats a wide variety of insects, plant matter, and detritus.

Habitat

The Pahrump poolfish is adapted to alkaline mineral springs and outflow streams. Adults prefer deeper pools; juveniles are found near the surface in shallower areas of the springs, where there is aquatic vegetation. The ancestral spring of this species maintained a constant, year-round temperature of 76°F (24.4°C).

Distribution

The Pahrump poolfish and two subspecies inhabited separate springs in the Pahrump Valley in Nevada. Both of the other subspecies (E. l. concavus and E. l. pahrump ) are now extinct. Originally, this fish was known only from Manse Spring on the Manse Ranch in Nye County. It was eliminated from this spring in 1975 when the water dried up. An early transplant site at Latos Pools near Boulder City was lost to a flood in 1975. Two transplanted populations of the Pahrump poolfish survive—in Corn-Creek Springs Pond on the Desert National Wildlife Range northwest of Las Vegas in Clark County, and in the Shoshone Pond southeast of Ely in White Pine County. No more than several hundred of these fish are thought to survive.

Threats

The Manse Spring dried up because of excessive groundwater pumping for irrigation. The drying of the spring had been predicted by biologists, who moved the fish to other localities. The Corn-Creek Springs population may eventually be threatened by increased groundwater pumping related to the growth of the Las Vegas metropolitan area. Because habitat in Shoshone Pond is considered less than optimal, U. S. Fish and Wildlife Service (FWS) biologists consider the site a temporary holding pool.

Conservation and Recovery

Low numbers and restricted distribution make the Pahrump poolfish greatly vulnerable to extinction. The major recovery strategy will be to protect the two existing populations until further transplant sites can be located. The FWS hopes to establish at least three protected populations, each of 500 or more adults. Success in this effort would warrant delisting the species. An attempt is currently being made to rehabilitate Manse Spring, the Pahrump poolfish's ancestral pool.

Contact

U. S. Fish and Wildlife Service
Regional Office, Division of Endangered Species
Eastside Federal Complex
911 N. E. 11th Ave.
Portland, Oregon 97232-4181
Telephone: (503) 231-6121
http://pacific.fws.gov/

References

La Rivers, Ira. 1962. Fishes and Fisheries of Nevada.

Nevada State Fish and Game Commission, Reno.U. S. Fish and Wildlife Service. 1980. "Pahrump Killifish Recovery Plan." U. S. Fish and Wildlife Service, Portland.