Ash Meadows Amargosa Pupfish

Cyprinodon nevadensis mionectes

Description

The Ash Meadows Amargosa pupfish, Cyprinodon nevadensis mionectes, is a small minnow, rarely exceeding 2.75 in (6.9 cm) in length. Normally silver gray and darker across the back, breeding males turn an iridescent silver-blue.

Behavior

This pupfish breeds throughout the year with peak periods in spring and early summer. Like other pupfish, it feeds on insects and small, aquatic invertebrates.

Habitat

The Ash Meadows Amargosa pupfish occupies 10 spring areas within Ash Meadows, all of which are designated as critical habitat. It is established outside of its native range in clay ponds located approximately 3.75 mi (2.25 km) west of the Area of Management Concern boundary. Most of these habitats lie on public land within the boundaries of Ash Meadows Refuge and include spring sources and outflow channels occupied by the species. The size of its habitats range from Crystal Pool, with a spring pool measuring 49 ft (15 m) in diameter and 20 ft (6 m) deep and discharging 62.9 gal (238.2 l)/ sec, to small springs in the Five Springs complex that have no spring pool and discharge less than 0.02 gal (0.09 l)/sec. The outflows from many springs occupied by this pupfish combine with one another. These confluences, however, are restricted to springs lying relatively close together and do not occur between springs separated by great distances.

Distribution

The Amargosa pupfish is endemic to the Ash Meadows region, an unusual desert wetland east of the Amargosa River in western California and eastern Nevada. These wetlands are maintained by springs and seeps fed by an extensive groundwater system.

The pupfish is restricted to the 10 spring areas within Ash Meadows, all of which are designated as critical habitat (Big Spring, Bradford Spring #2, Jack Rabbit Spring, Point of Rocks Spring, Tubbs Spring, Crystal Pool, Crystal Reservoir, Lower Crystal Marsh, Longstreet Spring, Five Springs, Rogers Spring, Fairbanks Spring, Peterson Reservoir, Clay Pits Spring, and Forest Spring).

The Amargosa pupfish occurs in a wide variety of habitats, including shallow and deep streams from springs. It lives in large springs and outflows at Ash Meadow, including Fairbanks, Rogers, Longstreet, Jack Rabbit, Big, and Point of Rocks Springs, Crystal Pool, and two springs of the Bradford Springs group. Most of these habitats lie on public land within the boundaries of Ash Meadows Refuge.

Population estimates made during June 1982 and July 1982 recorded 568 and 1,189 pupfish, respectively, in Jack Rabbit Spring and 1,189 and 1,822 pupfish, respectively, in Big Spring. Quantitative estimates have not been made for other populations nor have these old estimates been updated.

Threats

Since habitats of this pupfish provide most of the surface water in the area, they were the most altered during agricultural development. All have been altered by diversion into earthen or concrete channels, impoundment, drying due to pumping of local groundwaters, and/or elimination of riparian vegetation during ground leveling. They also support the widest variety of introduced organisms. These alterations eliminated fish populations from Soda Spring and Point of Rock Pool #1, and depressed the size of remaining populations by decreasing the amount of available habitat.

Conservation and Recovery

Critical Habitat for the Ash Meadows Amargosa pupfish has been designated in the following springs and their outflows in Nye County, Nevada: Fairbanks, Rogers, Longstreet, Crystal Pool, Bradford, Jack Rabbit, Big, Point of Rocks, and three unnamed springs. The Critical Habitat designation also includes a buffer zone immediately surrounding these springs. The buffer zone is essential to the conservation of the fish because it provides vegetative cover that contributes to providing the uniform water and feeding conditions preferred by the pupfish.

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

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.

Soltz, D. L., and R. J. Naiman, eds. 1978. "The Natural History of Native Fishes in the Death Valley System." Natural History Museum of Los Angeles County, Science Series 30:17.

U.S. Fish and Wildlife Service. 2 September 1983. "Determination of Endangered Status and Critical Habitat for Two Fish Species, Ash Meadows, Nevada." Federal Register 48(172):40178-40186.