The slimy sculpin (''Cottus cognatus'') is a freshwater species of fish belonging to the family Cottidae, which is the largest sculpin family. They usually inhabit cold rocky streams or lakes across North America, ranging from the

Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five la ...

, southeast Minnesota, northeast Iowa, southwest Wisconsin and northeast Canada. Slimy sculpins have also been found roaming the cold streams of eastern Siberia./> They are commonly confused with their closely related relatives,

Mottled sculpin The mottled sculpin (''Cottus bairdii'') is a species of freshawater ray-finned fish belonging to the family Cottidae, the typical sculpins. This species has a wide but scattered North American distribution. As the name suggests, its coloration ...

(''Cottus bairdi''), and with tubenose gobies who are both freshwater fishes as well. The slimy sculpin is a nocturnal fish that usually spends most of its time on the stream bottom and seeks shelter under rocks and logs, especially during spawning season. When it swims, it sometimes appears to be "hopping" along the bottom because of its inefficient ability to swim. This is partly due to the absence of a swim bladder, which normally gives

buoyancy Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the p ...

to a fish./> The fish has been studied in waters where there is current freshwater acidification. Sculpin were found to be less active and have lower rates of reproduction when found in these waters. For these reasons, slimy sculpin have been identified as a good

indicator species A bioindicator is any species (an indicator species) or group of species whose function, population, or status can reveal the qualitative status of the environment. The most common indicator species are animals. For example, copepods and other sma ...

for changes in acidification among lakes, ponds, and streams.>

Distribution

Slimy sculpin are native to the United States, Canada, and the Russian Federation. In North America, slimy sculpins are found mainly in

Lake Superior Lake Superior in central North America is the largest freshwater lake in the world by surface areaThe Caspian Sea is the largest lake, but is saline, not freshwater. and the third-largest by volume, holding 10% of the world's surface fresh w ...

and its tributaries,

Lake Michigan Lake Michigan is one of the five Great Lakes of North America. It is the second-largest of the Great Lakes by volume () and the third-largest by surface area (), after Lake Superior and Lake Huron. To the east, its basin is conjoined with that ...

, and small cold streams found in southwestern Wisconsin, as well as the upper

Mississippi River The Mississippi River is the second-longest river and chief river of the second-largest drainage system in North America, second only to the Hudson Bay drainage system. From its traditional source of Lake Itasca in northern Minnesota, it ...

basin.> They have also been found in other areas of North America such as southeast Minnesota (mostly in the

), northeast Iowa, the upper Columbia River, Alaska, and most all of Canada, especially in Ottawa. Slimy sculpins have also been found in eastern Siberia, Russia.>NatureServe. 2013. Cottus cognatus. The IUCN Red List of Threatened Species 2013: e.T202658A15363317. .

Physical description

The slimy sculpin can easily be distinguished by its pair of free and independent pelvic fins, as well as not possessing any scales.>Lyons, J. University of Wisconsin Sea Grant Institution. The Slimy Sculpin. Accessed from: http://www.seagrant.wisc.edu/home/Default.aspx?tabid=605&FishID=138 The first and second lobed dorsal fins are narrow and touch, the first dorsal fin has 7–9 soft spines while the second has 16–18 fin rays. The lateral line ends below the second dorsal fin and is incomplete, but the lateral line system still helps orient the slimy sculpin in streams by balancing the pressure of currents. The anal fin has 11–13 fin rays and the pelvic fins possess 13–14 fin rays and is in the thoracic position.>Harlan, J.R., E.B. Speaker, and J. Mayhew. 1987. Iowa fish and fishing. Iowa Conservation Commission, Des Moines, Iowa. 323pp. The mouth and snout are terminal and very wide, and also contain a band of fine conical teeth in both the upper and lower jaw, but do not possess

barbels In fish anatomy and turtle anatomy, a barbel is a slender, whiskerlike sensory organ near the mouth. Fish that have barbels include the catfish, the carp, the goatfish, the hagfish, the sturgeon, the zebrafish, the black dragonfish and s ...

. Adults weigh in around 3-7g and measure up to 6.3–9.1 cm long. The maximum weight of a slimy sculpin is 16.86g and the maximum length is 12.8 cm.>Eakins, R. J. 2016. Ontario Freshwater Fishes Life History Database. Version 4.68. Online database. (http://www.ontariofishes.ca) When the fish moves, it is an inconsistently rapid and darter-like motion that looks like it's hopping due to its irregular compressed body shape. The sides, back and head of slimy sculpins are dark brown/olive and are mottled with dark irregular blotches and a light cream/white belly. If slimy sculpins lie motionless for a while they camouflage in so well with their surroundings that it is almost impossible to distinguish them./> Although they don't have any scales, they do have a few fine prickles anteriorly below the lateral line.>Froese, R., C.V., Garilao, and Scarola, J.F. Fish Base Summary. Accessed from: http://www.fishbase.se/summary/4068 Slimy sculpins often look very similar to the

tubenose goby ''Proterorhinus'' is a genus of fishes, known as the tubenose gobies. These gobiid fish are native to Eurasia where they occur in the region of the Caspian and Black seas, inhabiting marine, brackish and fresh waters. The species ''Proterorhi ...

as well.

Habitat

Slimy sculpins often inhabit swift rocky-bottomed cold streams, oligotrophic lakes, and even brackish waters at a preferred temperature range of 9-14 °C.Saball, D. 2001 Sculpin: Global Flyfisher. Accessed from: http://globalflyfisher.com/streamers-forage-fish/sculpin Nocturnally active fishes, they usually roam around in deeper waters ranging from 37–108 meters deep./> During the breeding season, females often lay their eggs under sheltered areas like large objects such as rocks or tree roots found at the bottom of lakes or streams that males will guard.

Reproduction

Males often become dark on their backs and sides, and orange on their first dorsal fin during mating season./> Males having orange on their first dorsal fin during breeding season is a survival disadvantage, meaning that they can be more easily preyed upon, yet still survive- showing to females that they are fit and have high reproductive success, therefore females are more attracted to these visually distinctive males. Males find nesting sites about 12 cm wide for females, and attract them to these nesting sites until spawning occurs which usually takes place in late April and May under protected areas such as stones or tree roots./> Once the eggs are laid, males drive the females out and lure a new female into the nest to lay her eggs. Males then protect the nest for 3–4 weeks containing many females' eggs until all of the eggs hatch. Male slimy sculpins have also been seen protecting their young after hatching as well./> Slimy sculpins live up to 4–7 years.

Diet

The primary food slimy sculpin prey on is invertebrate benthic insects, which make up 85% or more of their diet, but has also been known to eat crustaceans, fish eggs, and small fish. The invertebrate benthic insects on which the sculpin prey includes aquatic insects such as

mayflies Mayflies (also known as shadflies or fishflies in Canada and the upper Midwestern United States, as Canadian soldiers in the American Great Lakes region, and as up-winged flies in the United Kingdom) are aquatic insects belonging to the order ...

caddis flies The caddisflies, or order Trichoptera, are a group of insects with aquatic larvae and terrestrial adults. There are approximately 14,500 described species, most of which can be divided into the suborders Integripalpia and Annulipalpia on the ba ...

, stoneflies, and dragonflies./> Predatious fish that eat slimy sculpin are

lake trout The lake trout (''Salvelinus namaycush'') is a freshwater char living mainly in lakes in northern North America. Other names for it include mackinaw, namaycush, lake char (or charr), touladi, togue, and grey trout. In Lake Superior, it can als ...

, brook trout,

salmon Salmon () is the common name In biology, a common name of a taxon or organism (also known as a vernacular name, English name, colloquial name, country name, popular name, or farmer's name) is a name that is based on the normal language of ...

northern pike The northern pike (''Esox lucius'') is a species of carnivorous fish of the genus ''Esox'' (the pikes). They are typical of brackish water, brackish and fresh waters of the Northern Hemisphere (''i.e.'' holarctic in distribution). They are kno ...

, and

burbot The burbot (''Lota lota'') is the only gadiformes, gadiform (cod-like) freshwater fish. It is also known as bubbot, mariah, loche, cusk, freshwater cod, freshwater ling, freshwater cusk, the lawyer, coney-fish, lingcod, and eelpout. The species ...

that are native to cool freshwater streams just like the slimy sculpin. There is speculation that sculpins have been known to prey on trout egg that were loose from the redds. However, sculpins predation on stoneflies has reduced stonefly predation on trout eggs and their young./>

Conservation status

This species is currently at low concern for conservative action and does not need protection or major management plans./>

References

External links

{{Taxonbar, from=Q610177 Cottus (fish) Freshwater fish of the Arctic Fish of the Great Lakes Fish described in 1836