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Cottus leiopomus

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Taxonomy [top]

Kingdom Phylum Class Order Family
ANIMALIA CHORDATA ACTINOPTERYGII SCORPAENIFORMES COTTIDAE

Scientific Name: Cottus leiopomus
Species Authority: Gilbert & Evermann, 1894
Common Name(s):
English Wood River Sculpin

Assessment Information [top]

Red List Category & Criteria: Near Threatened ver 3.1
Year Published: 2014
Date Assessed: 2011-11-10
Assessor(s): NatureServe
Reviewer(s): Smith, K. & Darwall, W.R.T.
Facilitator/Compiler(s): Hammerson, G.A. & Ormes, M.
Justification:
Listed as Near Threatened because extent of occurrence is less than 5,000 sq km, area of occupancy probably is less than 2,000 sq km, and habitat quality probably is slowly declining (less than 30 percent over 10 years or three generations) due to various ongoing threats that may be causing population decline and fragmentation. Currently, the distribution is not severely fragmented, population size is very large, and the species occurs in more than 10 locations, so the species does not fully qualify for the Vulnerable category.
History:
1996 Vulnerable
1994 Rare (Groombridge 1994)
1990 Rare (IUCN 1990)

Geographic Range [top]

Range Description: Range includes the Wood River basin and its three associated subbasins, the Big Wood River, Little Wood River, and Camas Creek, in south-central Idaho (Meyer et al. 2008).
Countries:
Native:
United States
Range Map: Click here to open the map viewer and explore range.

Population [top]

Population: Meyer et al. (2008) surveyed 102 sites that were less than 10 meters wide and found C. leiopomus in 20 sites; it is likely that the species occurred in additional sites that were not sampled. Zaroban (2010) found this species in a large number of sites likely representing at least several dozen distinct occurrences (subpopulations); the species was detected in 49 subwatersheds.

Meyer et al. (2008) estimated population size at 1.36 million individuals at least 20 mm total length; this may have been an underestimate because larger streams were not sampled.

Trend over the past three generations is uncertain, but distribution and abundance have probably been slowly declining.
Population Trend: Decreasing

Habitat and Ecology [top]

Habitat and Ecology: This sculpin occurs mainly in creeks and small rivers with cool, clear waters and swift current; bottom dweller. It is found in riffle areas with gravel-rubble substrate (Lee et al. 1980, Page and Burr 2011).

Meyer et al. (2008) found that Wood River Sculpin presence increased as stream width:depth ratio and percent cobble/boulder substrate increased and stream gradient decreased.

In the Big Wood River and on the Soldier Creek Stapp Preserve (TNC), this species occurred mainly in riffles and, to a lesser extent in the latter site, beaver dam pools, where the fishes may have been trapped in unfavourable habitat (Merkley and Griffith 1992). It uses seasonal side channels during high water (Merkley and Griffith 1992). Individuals may burrow into bottom mud when disturbed. This species may be most abundant where trout populations are relatively low (Merkley and Griffith 1992). Sculpins are indicators of high water quality (cool temperatures, high oxygen content, low pollution).

Eggs are laid probably on the underside of rocks in cobble/boulder areas.
Systems: Freshwater

Threats [top]

Major Threat(s): Threatened by habitat degradation as a result of land development, water diversion, removal of streamside vegetation, and poor land management practices (Simpson and Wallace 1982); these contribute to bank erosion, siltation, and excessive water warming (Spahr et al. 1991), as well as population fragmentation (Meyer et al. 2008).

"The development of irrigation projects, floodplain encroachment, and stream channelization from residential development, as well as migration barriers at road crossings have resulted in a loss of habitat and connectivity among populations. Loss of riparian habitat and reduced flows in streams can increase water temperature, reducing habitat suitability. Water quality degradation from pesticides and herbicides affects this sculpin and aquatic insects prey. Dams, diversion structures, culverts, and dewatered stream channels can fragment populations resulting in loss of gene flow. Introduced fish can increase predation and competition." Source: Idaho Fish and Game, http://fishandgame.idaho.gov/ifwis/cwcs/pdf/Wood%20River%20Sculpin.pdf.

Jelks et al. (2008) categorized this species as Threatened due to (1) present or threatened destruction, modification, or reduction of habitat or range and (2) restricted range.

Conservation Actions [top]

Conservation Actions: Better information is needed on life history and reproductive biology. Bear Lake should be surveyed for precise population numbers and distribution.

Citation: NatureServe 2014. Cottus leiopomus. The IUCN Red List of Threatened Species. Version 2014.3. <www.iucnredlist.org>. Downloaded on 26 November 2014.
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