Slimy Sculpin

Characteristics

The head and anterior body are flattened dorso-ventrally with the posterior body and caudal peduncle compressed laterally. The mouth is terminal with numerous teeth in narrow bands on the upper and lower jaws. The head, back and sides are olive-brown with dark mottling. The lower region of the head and belly are lighter to whitish. It has two-lobed, narrowly-connected dorsal fins. The frontal dorsal fin has 7 to 9 soft spines and the second lobe has 16 to 18 rays. The anal fin has 11 to 13 rays; the pelvic fins are thoracic with a single spine and 3 pelvic rays. The pectoral fin has 13 to 14 rays. Scales are absent and the lateral line is incomplete, ending under the second dorsal fin. Fish rarely exceed 4-inches long.

Distribution

Only in the northeast corner of Iowa; common in many cold water streams in this region.

Foods

Larval aquatic insects, invertebrates

State Record

State Records are not documented for non-game species.

Expert Tip

None

Details

The Slimy Sculpin is common in many coldwater streams in northeast Iowa. With only one exception, collections made in Iowa before 1969 reported only Slimy Sculpin. Noting the difficulty in distinguishing between Slimy and Mottled Sculpins, it is likely that past surveys probably contained both species.

The Slimy Sculpin lives in cold, headwater streams with moderate to fast currents in the Driftless Area of southwestern Wisconsin, northeastern Iowa, and southeastern Minnesota. In the Great Lakes area, Slimy Sculpins are often found in deep, oligotrophic lakes as well.

The Slimy Sculpin lives on the stream bottom. Movements are darter-like in their speed and often look like they are hopping. Activity is mostly nocturnal. When the fish lies motionless in one place for long periods of time, its coloration perfectly blends into the surroundings making it difficult to see.

Spawning takes place in late April and May. A nest cavity is cleaned by the male; eggs are deposited by the female in clusters on the undersides of stones. The male guards the nest 3 to 4 weeks, until the fry leave. Records show Slimy Sculpin living at least 5 years.

Sculpins have long been accused of preying on trout eggs and fry and even for direct competition for benthic invertebrates. Most of the trout eggs eaten are probably loose eggs that were not buried in the redd. Little evidence is available which shows sculpin limit trout numbers. It has even been speculated that sculpin predation on predaceous stoneflies may increase the numbers of drifting herbivorous insects for trout and reduce stonefly predation on trout eggs and young.

Recent stream sampling information is available from Iowa DNR's biological monitoring and assessment program.

Sources:

Harlan, J.R., E.B. Speaker, and J. Mayhew. 1987. Iowa fish and fishing. Iowa Conservation Commission, Des Moines, Iowa. 323pp.

Loan-Wilsey, A. K., C. L. Pierce, K. L. Kane, P. D. Brown and R. L. McNeely. 2005. The Iowa Aquatic Gap Analysis Project Final Report. Iowa Cooperative Fish and Wildlife Research Unit, Iowa State University, Ames

Photo credit: Canada's Polar Life