Cyprinodon radiosus

Taxonomy

Assessment Information

Geographic Range

Population

Habitat and Ecology

Threats

Conservation Actions

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Taxonomy [top]

Kingdom	Phylum	Class	Order	Family
ANIMALIA	CHORDATA	ACTINOPTERYGII	CYPRINODONTIFORMES	CYPRINODONTIDAE

Scientific Name:

Cyprinodon radiosus

Species Authority:

Miller, 1948

Common Name/s:

English

–

Owens Pupfish

Assessment Information [top]

Red List Category & Criteria:

Endangered B1ab(iii) ver 3.1

Year Published:

2010

Assessor/s:

NatureServe (G. Hammerson)

Reviewer/s:

Mire, J.B. (Freshwater Fish Red List Authority), Collen, B., Richman, N. & Ram, M. (Sampled Red List Index Coordinating Team)

Justification:
Cyprinodon radiosus has been assessed as Endangered under criterion B1ab(iii). This species is estimated to have an extent of occurrence less than 5,000 km², and is now only known from five small locations. At one stage this species was thought to be extinct. Only two of these five subpopulations are said to be stable, however they are still considered to be threatened as these require active management to ensure no threats are present. Conservation efforts need to focus on active management of all five subpopulations to rid all threats and maintain a suitable breeding population.

History:

1996	–	Endangered
1994	–	Endangered (Groombridge 1994)
1990	–	Endangered (IUCN 1990)
1988	–	Endangered (IUCN Conservation Monitoring Centre 1988)
1986	–	Endangered (IUCN Conservation Monitoring Centre 1986)

Geographic Range [top]

Range Description:	This pupfish is endemic to the Owens Valley, California, from Fish Slough and its springs (Mono County) near Bishop downstream to Owens Lake (Inyo County), including springs around the lake (Moyle 2002). It is now confined to several special refuges in the Owens Valley (Bolster 1990, Mire 1993, Moyle 2002). This species is estimated to have an extent of occurrence less than 5,000 km².
Countries:	Native: United States
Range Map:	Click here to open the map viewer and explore range.

Population [top]

Population:	This species is represented by a small number of occurrences (subpopulations). As of the beginning of the 21st century, this species was regarded as stable in only two of five refuges (Moyle 2002), but they remained threatened because these sites require active, ongoing management to keep the habitat favourable for pupfishes and to keep out alien species (Moyle 2002). See Minckley et al. (1991) for a fairly detailed account of the historical status of this species. The existing population is descended from fewer than 1,000 individuals rescued from a drying habitat in 1969 (Pister pers. comm.).
Population Trend:	Decreasing

Population:

This species is represented by a small number of occurrences (subpopulations). As of the beginning of the 21st century, this species was regarded as stable in only two of five refuges (Moyle 2002), but they remained threatened because these sites require active, ongoing management to keep the habitat favourable for pupfishes and to keep out alien species (Moyle 2002).

See Minckley et al. (1991) for a fairly detailed account of the historical status of this species.

The existing population is descended from fewer than 1,000 individuals rescued from a drying habitat in 1969 (Pister pers. comm.).

Population Trend:

Decreasing

Habitat and Ecology [top]

Habitat and Ecology:	This pupfish was once abundant in shallow, clear, warm (about 10–25°C) sloughs, spring pools, irrigation ditches, marshes with emergent bullrushes and Chara mats, and flooded pastures along the Owens River (Lee et al. 1980, Moyle 2002). Now it occurs mostly in deep pools and shallows of artificially created refugia (Bolster 1990). It needs good quality water, aquatic vegetation, and a silt- or sand-covered bottom. Males establish spawning territories around rocks or vegetation where adhesive eggs can be laid and guarded. Females avoid male territories except when ready to spawn. Spawning substrate includes silty bottoms, submerged plants, algal clumps, rocks, or crevices, at depths up to 2 m (Moyle 2002). Larvae and juveniles stay close to the substrate (Moyle 2002). In early morning and late afternoon, mixed aggregations of 10–20 males and females swarm throughout the habitat, foraging by picking invertebrates and detritus from rocks and vegetation (Mire 1993). Hatching time is 6 days at an air temperature range of 24–27°C (Mire and Millet 1994).
Systems:	Freshwater

Habitat and Ecology:

This pupfish was once abundant in shallow, clear, warm (about 10–25°C) sloughs, spring pools, irrigation ditches, marshes with emergent bullrushes and Chara mats, and flooded pastures along the Owens River (Lee et al. 1980, Moyle 2002). Now it occurs mostly in deep pools and shallows of artificially created refugia (Bolster 1990). It needs good quality water, aquatic vegetation, and a silt- or sand-covered bottom. Males establish spawning territories around rocks or vegetation where adhesive eggs can be laid and guarded. Females avoid male territories except when ready to spawn. Spawning substrate includes silty bottoms, submerged plants, algal clumps, rocks, or crevices, at depths up to 2 m (Moyle 2002). Larvae and juveniles stay close to the substrate (Moyle 2002). In early morning and late afternoon, mixed aggregations of 10–20 males and females swarm throughout the habitat, foraging by picking invertebrates and detritus from rocks and vegetation (Mire 1993). Hatching time is 6 days at an air temperature range of 24–27°C (Mire and Millet 1994).

Systems:

Freshwater

Threats [top]

Major Threat(s):	Population declines observed in this species, have been attributed to water diversion and subsequent habitat alteration (loss of seasonally flooded shallows along the Owens River), and competition with, and predation by, introduced species. Current threats include introduced species [Largemouth Bass (which eliminated pupfish from the Owens Valley Native Fishes Sanctuary and BLM Spring; Moyle 2002), mosquitofish, bullfrogs, crayfish], encroaching vegetation (cattails, tules, and other emergent plants), and habitat degradation (including vandalism). All populations are in small, artificial situations, vulnerable to stochastic fluctuations.

Major Threat(s):

Population declines observed in this species, have been attributed to water diversion and subsequent habitat alteration (loss of seasonally flooded shallows along the Owens River), and competition with, and predation by, introduced species. Current threats include introduced species [Largemouth Bass (which eliminated pupfish from the Owens Valley Native Fishes Sanctuary and BLM Spring; Moyle 2002), mosquitofish, bullfrogs, crayfish], encroaching vegetation (cattails, tules, and other emergent plants), and habitat degradation (including vandalism). All populations are in small, artificial situations, vulnerable to stochastic fluctuations.

Conservation Actions [top]

Conservation Actions:	This species was once thought to be extinct, but has since been identified in a few, small refugia in eastern California. There are approximately five remaining occurences of this species, with only a few of these adequately protected. Recovery plans need to protect all five populations with at least 500 overwintering individuals, from all potential threats. Cyprinodon radiosus was previously assessed as Endangered (criterion A2ce) on the 1996 IUCN Red List version 2.3.

Conservation Actions:

This species was once thought to be extinct, but has since been identified in a few, small refugia in eastern California. There are approximately five remaining occurences of this species, with only a few of these adequately protected. Recovery plans need to protect all five populations with at least 500 overwintering individuals, from all potential threats.

Cyprinodon radiosus was previously assessed as Endangered (criterion A2ce) on the 1996 IUCN Red List version 2.3.

Citation:	NatureServe (G. Hammerson) 2010. Cyprinodon radiosus. In: IUCN 2011. IUCN Red List of Threatened Species. Version 2011.2. <www.iucnredlist.org>. Downloaded on 25 May 2012.
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