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Gambusia gaigei

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA ACTINOPTERYGII CYPRINODONTIFORMES POECILIIDAE

Scientific Name: Gambusia gaigei
Species Authority: Hubbs, 1929
Common Name(s):
English Big Bend Gambusia

Assessment Information [top]

Red List Category & Criteria: Vulnerable D2 ver 3.1
Year Published: 2013
Date Assessed: 2012-02-03
Assessor(s): NatureServe
Reviewer(s): Smith, K. & Darwall, W.R.T.
Facilitator/Compiler(s): Hammerson, G.A. & Ormes, M.
Justification:
This species is listed as Vulnerable because it occurs in not more than five locations and has an area of occupancy of less than 20 sq km.
History:
1996 Vulnerable
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 species is restricted to springs in Big Bend National Park, Brewster County, Texas (Page and Burr 2011). Two populations are believed to have originally existed; one at Boquillas Spring and the other at "Spring 4" east of the Rio Grande Village campground in the national park. The Boquillas Spring population is extinct (spring stopped flowing in the 1950s), and the Spring 4 population was once extirpated (Hubbs et al. 2008). The species now consists of descendants of three individuals of the Spring 4 population and is maintained in refuges in Big Bend National Park and at the U.S. National Fish Hatchery in Dexter, New Mexico, as well as Spring 4 (Hubbs et al. 2008).
Countries:
Native:
United States
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: This species is represented by just a few extant occurrences, one of which is in a native habitat.

It was once depleted to three individuals. At present, several thousand Big Bend Gambusias inhabit two spring pool refugia and a spring-fed drainage ditch; smaller populations also occur in the presumed original habitat and the spring's outflow channel (Hubbs et al. 2002).

Trend over the past 10 years or three generations is uncertain but likely relatively stable.
Population Trend: Stable

Habitat and Ecology [top]

Habitat and Ecology: Habitat includes vegetated, spring-fed sloughs and ponds (Page and Burr 2011); clear, warm-water springs, outflows, and marshes (Minckley et al. 1991). Survival apparently is best under stenothermal conditions. The species persists principally because of its ability to live in artificially ponded spring waters (Minckley and Deacon 1991).
Systems: Freshwater

Threats [top]

Major Threat(s): Major threats include habitat loss from declining spring flows and reduced surface waters, competition with introduced species, and hybridization with introduced fishes.

Conservation Actions [top]

Conservation Actions: Park Service management goals include supplementing spring flows with well water in the dry season, restoration of habitat to approximate pre-development conditions, eradication of mosquitofish from springs and streams in the campground area, and eventual establishment of Gambusia gaigei in other suitable locations (Matthews and Moseley 1990). Any mosquitofish detected in habitat should be quickly eradicated.

Recovery plan: Rio Grande Fishes Recovery Team (1984).

Extant populations should be monitored regularly in order to be able to detect problems such as introductions of mosquitofish.

Citation: NatureServe 2013. Gambusia gaigei. The IUCN Red List of Threatened Species. Version 2014.2. <www.iucnredlist.org>. Downloaded on 20 October 2014.
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