The Nonindigenous Occurrences section of the NAS species profiles has a new structure. The section is now dynamically updated from the NAS database to ensure that it contains the most current and accurate information. Occurrences are summarized in Table 1, alphabetically by state, with years of earliest and most recent observations, and the tally and names of drainages where the species was observed. The table contains hyperlinks to collections tables of specimens based on the states, years, and drainages selected. References to specimens that were not obtained through sighting reports and personal communications are found through the hyperlink in the Table 1 caption or through the individual specimens linked in the collections tables.

Cottus extensus
Cottus extensus
(Bear Lake Sculpin)
Native Transplant

Copyright Info
Cottus extensus Bailey and Bond, 1963

Common name: Bear Lake Sculpin

Taxonomy: available through www.itis.govITIS logo

Identification: Page and Burr (1991); Sigler and Sigler (1996).

Size: 17 cm TL

Native Range: Bear Lake, Utah and Idaho (Page and Burr 1991).

Native range data for this species provided in part by NatureServe NS logo
Hydrologic Unit Codes (HUCs) Explained
Interactive maps: Point Distribution Maps

Nonindigenous Occurrences:

Table 1. States with nonindigenous occurrences, the earliest and latest observations in each state, and the tally and names of HUCs with observations†. Names and dates are hyperlinked to their relevant specimen records. The list of references for all nonindigenous occurrences of Cottus extensus are found here.

StateFirst ObservedLast ObservedTotal HUCs with observations†HUCs with observations†
UT198719871Upper Green-Flaming Gorge Reservoir
WY198719871Upper Green-Flaming Gorge Reservoir

Table last updated 6/19/2024

† Populations may not be currently present.

Ecology: Bear Lake Sculpin are small (generally less than 90 mm TL) cottids endemic to Bear Lake, and are one of the most abundant fishes in the lake. They occur throughout the lake, with adults spawing in littoral areas on rocky substrate, and juveniles found throughout the lake in benthic habitats (to 50 m depth) (Sigler and Sigler 1996; Ruzycki et al. 1998). The are benthic carnivores, primarily consuming zooplankton and benthic invertebrates. Juveniles occuring in the deeper profundal portion of the lake perform diel vertical migrations to warmer, shallower waters at night, an adaptation to speed digestion (Wurtsbaugh and Neverman 1988).

Means of Introduction: Intentionally stocked into Flaming Gorge Reservoir (Sigler and Sigler 1987, 1996), apparently to serve as forage for large predatory fish species.

Status: Established in Flaming Gorge Reservoir (Utah Division of Wildlife Resources 2012).

Impact of Introduction: The impacts of this species are currently unknown, as no studies have been done to determine how it has affected ecosystems in the invaded range. The absence of data does not equate to lack of effects. It does, however, mean that research is required to evaluate effects before conclusions can be made.

Remarks: In its native habitat this species is very abundant and considered important forage for large predators such as cutthroat trout and lake trout (Sigler and Sigler 1987, 1996).

References: (click for full references)

Page, L.M., and B.M. Burr. 1991. A field guide to freshwater fishes of North America north of Mexico. The Peterson Field Guide Series, volume 42. Houghton Mifflin Company, Boston, MA.

Ruzycki, J.R., W.A. Wurtsbaugh, and C. Lay. 1998. Reproductive ecology and early life history of a lacustrine sculpin, Cottus extensus (Teleostei, Cottidae). Environmental Biology of Fishes 53:117-127.

Sigler, W.F., and J.W. Sigler. 1987. Fishes of the Great Basin: A Natural History. University of Nevada Press, Reno, NV.

Sigler, W.F., and J.W. Sigler. 1996. Fishes of Utah. University of Utah Press, Salt Lake City, UT.

Utah Division of Wildlife Resources. 2012. Bear Lake sculpin. http://dwrcdc.nr.utah.gov/rsgis2/search/Display.asp?FlNm=cottexte. Accessed on 24 Jan 2012

Wurtsbaugh, W.A. and D. Neverman. 1988. Post-feeding thermotaxis and daily vertical migration in a larval fish. Nature 333:846-848.

Other Resources:
FishBase Summary

Author: Pam Fuller, and Matt Neilson

Revision Date: 1/24/2012

Peer Review Date: 1/24/2012

Citation Information:
Pam Fuller, and Matt Neilson, 2024, Cottus extensus Bailey and Bond, 1963: U.S. Geological Survey, Nonindigenous Aquatic Species Database, Gainesville, FL, https://nas.er.usgs.gov/queries/FactSheet.aspx?speciesID=503, Revision Date: 1/24/2012, Peer Review Date: 1/24/2012, Access Date: 6/19/2024

This information is preliminary or provisional and is subject to revision. It is being provided to meet the need for timely best science. The information has not received final approval by the U.S. Geological Survey (USGS) and is provided on the condition that neither the USGS nor the U.S. Government shall be held liable for any damages resulting from the authorized or unauthorized use of the information.


The data represented on this site vary in accuracy, scale, completeness, extent of coverage and origin. It is the user's responsibility to use these data consistent with their intended purpose and within stated limitations. We highly recommend reviewing metadata files prior to interpreting these data.

Citation information: U.S. Geological Survey. [2024]. Nonindigenous Aquatic Species Database. Gainesville, Florida. Accessed [6/19/2024].

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For general information and questions about the database, contact Wesley Daniel. For problems and technical issues, contact Matthew Neilson.