Columbia Slimy Sculpin - Cottus cognatus
The slimy sculpin is native west of the Continental Divide, and a recent study (Neely et al. 2010) showed through DNA work that the Columbia Basin slimy sculpin is more closely related to a Russian sculpin in Siberia--not the slimy sculpin of the eastern U.S., as some previously thought. Like the rocky mountian sculpin, it prefers clear, cold, rocky streams but will also be found along cobbly shorelines of lakes. Like all sculpins, this species is a benthic invertivore meaning it eats primarily aquatic insects. They occasionally eat small fish or trout eggs but this is not a large part of their diet. All freshwater sculpins are spring spawners. The males select spawning sites on the undersides of rocks. The female is courted, enters the nest, and deposits a mass of adhesive eggs upside down on the ceiling of the nest. The male then guards the nest and newly-hatched young sculpins with vigilance.
The back and sides are brown to black with mottling; dark bands are often present. The underside is white. The first dorsal fin is fringed with orange on breeding males. No palatine teeth are present. Pelvic fins have 3 or 4 soft rays; if a fourth (inner) ray is present, it is usually two-thirds or less the length of the longest. Other Montana sculpins have four fully developed soft rays. Note: sculpin pelvic fins have one spine in addition to the soft rays. It is encased in a fleshy membrane with the first (outer) ray and is not distinct.
Western Hemisphere Range
Found throughout western MT in cold, clear rivers and streams.
Summary of Observations Submitted for Montana
Number of Observations:
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Map Help and Descriptions
(Observations spanning multiple months or years are excluded from time charts)
Its usual habitat is in the rocky riffles of cold, clear streams, but it is sometimes found along the rubble beaches of lakes, especially near the mouths of inlet streams (Brown 1971).
Food is comprised of mostly immature aquatic insects and invertebrates, but also includes any small fish available (Brown 1971).
Construction of the Libby Dam wiped out populations in a stretch of river now occupied by Lake Koocanusa (Huston 1984).
Spawning occurs in spring (Brown 1971). Incubation is in 30-40 days at 48-50 degrees F. They may become sexually mature at 2 years (Weisel 1957). Populations in northern Saskatchewan spawned in early May at 46 degrees F. with eggs hatching in 4 weeks (Scott 1973).
- Additional ReferencesLegend: View Online Publication
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- Brandt, S. B. 1986. Ontogenetic shifts in habitat, diet and diel-feeding periodicity of slimy sculpin in Lake Ontario. Trans. Am. Fish. Soc. 115:711-715.
- Brandt, S., and S. Madon. 1986. Rainbow smelt, Osmerus mordax, predation on slimy sculpin, Cottus cognatus, in Lake Ontario. J. Great Lakes Res. 12:322-325.
- Cuker, B. E., M. E. McDonald, and S. C. Mozley. 1992. Influences of slimy sculpin (Cottus cognatus) predation on the rocky littoral invertebrate community in an arctic lake. Hydrobiologia 240:83-90.
- Godkin, C. M., W. J. Christie, and D. E. McAllister. 1982. Problems of species identity in the Lake Ontario sculpins Cottus bairdi and C. cognatus. Can. J. Fish. Aquat. Sci. 39:1373-1382.
- Hanson, K. L., A. E. Hershey, and M. E. McDonald. 1992. A comparison of slimy sculpin (Cottus cognatus) populations in arctic lakes with and without piscivorous predators. Hydrobiologia 240:189-201.
- Hughes, G. W. and A. E. Peden. 1984. Life history and status of the shorthead sculpin (COTTUS CONFUSUS: Pisces, Cottidae) in Canada and the sympatric relationship to the slimy sculpin (COTTUS COGNATUS). Can. J. Zool. 62:306-311.
- Lawler, G. H. 1952. A new North American host for the fish parasite Triaenophorus nodulosus (Pallus). Can. Field-Nat. 66:111. [in C. cognatus]
- Lyons, J. 1990. Distribution and morphological variation of the slimy sculpin (COTTUS COGNATUS) in the north central United States. Can. J. Zool. 68:1037-1045.
- McAllister, D. E. 1964. Distinguishing characters for the sculpins Cottus bairdii [sic] and C. cognatus in eastern Canada. J. Fish. Res. Board Can. 21:1339-1342.
- Mousseau, T. A., N. C. Collins, and G. Cabana. 1988. A comparative study of sexual selection and reproductive investment in the slimy sculpin, Cottus cognatus. Oikos 51:156-162.
- Otto, R., and J. Rice. 1977. Responses of a freshwater sculpin (Cottus cognatus gracilis) to temperature. Trans. Am. Fish. Soc. 106:89-94.
- Owens, R. W., and R. A. Bergstedt. 1994. Response of slimy sculpins to predation by juvenile lake trout in southern Lake Ontario. Trans. Am. Fish. Soc. 123:28-36.
- Petrosky, C., and T. Waters. 1975. Annual production by the slimy sculpin population in a small Minnesota trout stream. Trans. Am. Fish. Soc. 104:237-244.
- Savino, J. F., and M. G. Henry. 1991. Feeding rate of slimy sculpin and burbot on young lake char in laboratory reefs. Environ. Biol. Fishes 31:275-282.
- Strauss, R. E. 1986. Natural hybrids of the freshwater sculpins Cottus bairdi and Cottus cognatus (Pisces: Cottidae): electrophoretic and morphometric evidence. Am. Mid. Nat. 115:87-105.
- Symons, P., J. Metcalfe, and G. Harding. 1976. Upper lethal and preferred temperatures of the slimy sculpin, Cottus cognatus. J. Fish. Res. Board Can. 33:180-183.
- Zimmerman, E. G., and M. C. Wooten. 1981. Allozymic variation and natural hybridization in sculpins, COTTUS CONFUSES and COTTUS COGNATUS. Biochemical Systematics and Ecology 9(4):341-346.