Railroad Valley springfish

Crenichthys nevadae

SPECIES CODE: E04T V01

STATUS:

Listed Threatened with Critical Habitat on March 31, 1986 (51 FR 10857 10865). Recovery Plan approved on March 15, 1997.

Note: All descriptions are abstracted and/or taken from the Recovery Plan (1996), excluding information cited from the NatureServe Explorer (2001).

SPECIES DESCRIPTION:

The Railroad Valley springfish is under the genus Crenichthys, this genus was once a part of the Cyprinodontidae family but is now in the family Goodeidae (NatureServe Explorer 2001). The average total length of the Railroad Valley springfish varies between 23-39mm (.9-1.5 inches), depending on the spring it occupies, although individuals may attain a total length exceeding 70mm (2.7 inches). The species is an opportunistic feeder, feeding primarily on filamentous algae in the spring, and animal foods in the summer.

REPRODUCTION AND DEVELOPMENT:

Railroad Valley springfish spawning has never been observed.

Examination of the reproductive organs of Railroad Valley springfish collected from Big Warm Spring and Big Spring revealed differences in developmental timing (Williams 1986). Females from Big Warm Spring had well-developed ovaries from spring through autumn, with the best development during the summer. Spawning at Big Warm Spring, although never actually observed, probably occurs from March through November. Railroad Valley springfish collected from near the terminus of the Big Spring outflow exhibited greatest ovarian development in the spring, with well-developed ovaries in the autumn and winter, but poor development in the summer (Williams 1986). Spawning in the outflow of Big Spring, although never observed, presumably occurs during the autumn, winter, and spring months (Williams 1986).

RANGE AND POPULATION LEVEL:

The Railroad Valley springfish is the only fish species native to the thermal spring systems of Railroad Valley, Nye County, Nevada. The Railroad Valley springfish still occur in all six known historical habitats; four thermal springs near Locke’s Ranch (Big, North, Hay Corral, Reynolds) and two thermal springs on the Dockwater Shoshone Indian Reservation (Big Warm and Little Warm).

No numerical estimates of the Duckwater Indian Reservation populations have ever been made. The Big Warm Spring population was described as “teeming” and “abundant” during the 1930’s, but declined to “exceedingly rare” between 1981 and 1982, following introduction of nonnative fishes and installation of a catfish rearing facility. A “teeming population occupied Little Warm Spring in 1934, and the springfish remain “common” despite the draining of an associated marsh and diversion of the spring outflow into two ditches.

The species has also been introduced into Chimney Springs, approximately six miles south of Locke’s Ranch, a seepage area which forms small thermal ponds at Sodaville in Mineral County, Nevada, and into springs at the source of Hot Creek Canyon, approximately 40 miles west of Locke’s Ranch. In 1994, the population at Chimney Springs was estimated at 5,800 individuals. The population at Hot Creek Canyon is located on the Dugan Ranch in an unnamed warm spring, and no recent population estimate has been made.

HABITAT:

The springs in which the fish inhabit range from 30ºC to 39ºC, with Chimney Springs being the hottest, ranging from 63ºC to 66ºC (145ºF to 151ºF). In their natural environment, Railroad Valley springfish will occupy habitats with water temperatures at the extremes of their tolerance limits (e.g., 14ºC or 40ºC; 57º or 104ºF) for limited amounts of time.

PAST THREATS:

All of the springs historically inhabited by the Railroad Valley springfish have been altered by man’s activity, and springfish populations have decreased in all habitats throughout its range. Diking of springpools, diversion of outflows, and channelization of outflow creeks have reduced suitable habitat for the Railroad Valley springfish at Big, Hay Corral, Big Warm and Little Warm Springs. The spring pools at Big Warm Spring and Hay Corral Spring are impounded by a concrete diversion structure and an earthen dam, respectively. Aquatic and riparian habitats around North Spring have been trampled and heavily grazed by cattle.

The populations at Chimney Springs have two major setbacks. In 1981, the introduced population at Chimney Springs was lost after spring discharge decreased due to pumping of underground aquifers. Another population was reintroduced after flows resumed. In addition to Chimney Springs, several other springs to the south of Locke’s Ranch

also failed during 1981. In 1988, cattle trampled the berms creating the three ponds, eliminating the fish in the ponds. However, a few were observed downstream and following repair, the fish were able to recolonize the ponds.

In 1984, the outflow channel from Little Warm Spring was channelized and its bordering marsh dried and burned to modify and improve diversions to nearby agricultural lands. Prior to this action, the habitat in Little Warm Spring was the most stable environment occupied by the springfish. Springfish habitat in the channel was approximately 400 yards long, 2 yards wide, and 1 yard deep, lightly vegetated, and bordered by deeply recessed undercut banks supporting mature marsh vegetation. Since channelization, this quality habitat is approximately 20 yards long and 1 yard wide.

The Big Warm Spring population has declined due to the introduction of guppies, mollies (Poecilia sp.), mosquitofish (Gambusia affinis), and catfish (Ictalurus punctatus). The introduced fish compete with and prey upon Railroad Valley springfish.

CURRENT THREATS:

The long term threat to the Railroad Valley springfish continues to be the alteration of its thermal spring habitats, excess groundwater pumping, and the introduction of exotic organisms, especially fishes.

CONSERVATION MEASURES:

LITERATURE CITED:

Deacon, J.E., T.B. Hardy, J. Pollard, W. Taylor, J. Landye, J. Williams, C. Williams, P. Greger, and M. Conrad. 1980. Environmental analysis of four aquatic habitats in east-central Nevada: June-September, 1980. Interim Final Summary Report to HDR Sciences.

NatureServe Explorer: An online encyclopedia of life [web application]. 2001. Version 1.6 . Arlington, Virginia, USA: NatureServe. Available: http://www.natureserve.org/explorer. (Accessed: June 25, 2002 ).

U.S. Fish and Wildlife Service. 1996. Railroad Valley Springfish (Crenichthys nevadae) Recovery Plan. Portland, Oregon. 56 pages.

Williams, C.D. 1986. Life history of the Railroad Valley springfish, Crenichthys nevadae Hubbs (Cyprinodontidae), of east-central Nevada. M.S. Thesis. Department of Biological Sciences, California State University, Sacramento.