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Becker, George C. / Fishes of Wisconsin

Sculpin family - cottidae,   pp. 963-981 ff. PDF (8.9 MB)

Page 974

974    Sculpin Family-Cottidae 
Slimy Sculpin 
Cottus cognatus Richardson. Cottus-the bull's head, 
     an old name of the European sculpin called 
     miller's thumb; cognatus-related (to the Euro- 
     pean species Cottus gobio). 
Other common names: slimy muddler, common 
     slimy muddler, northern sculpin, sculpin, star- 
     gazer, Bear Lake bullhead, cockatouch, cottus, 
     big fin, northern miller's thumb (called miller's 
     thumb because its broad, flat head resembles 
     the flattened thumb of the miller who had the 
     misfortune to have his thumb crushed between 
Adult 80 mm, L. Michigan, Kewaunee Harbor (Kewaunee Co.), 7 
Apr. 1962. Lateral view above and dorsal view below. 
Head and anterior body flattened dorsoventrally; 
posterior body and caudal peduncle compressed lat- 
erally. Average length 76 mm (3 in). TL - 1.24 SL (in 
Citron Creek, Crawford County); TL = 1.19 SL (in 
Lake Michigan) (Foltz 1976). Depth into TL 5.0-5.9. 
Head length into TL 3.6-4.5. Snout rounded in lat- 
eral view. Mouth terminal, upper lip often protrud- 
ing slightly beyond lower. Numerous teeth in nar- 
row bands on upper and lower jaws; palatine teeth 
usually absent. Two midline mandibular pores. Gill 
membranes broadly joined to isthmus. Upper pre- 
opercular spine large, directed upward, and curving 
slightly inward; lower 2 preopercular spines small, 
directed downward, and covered by skin. Dorsal fins 
2, narrowly connected; first dorsal fin with 7-9 soft 
spines; second dorsal fin usually with 16-18 rays (last 
ray usually single). Anal fin rays usually 11-13 (last 
ray usually single). Pelvic fins thoracic, with 1 spine 
and 3 pelvic rays but appearing as only 3 elements 
(the spine and first ray encased in a single fleshy 
membrane); pectoral rays usually 13-14. Typical scales 
absent, but small patch of prickles present on sides 
below lateral line at level of first dorsal fin. Lateral 
line incomplete, terminating under second dorsal fin. 
Chromosomes 2n = 48 (W LeGrande, pers. comm.). 
  Upper region of head, back, and sides dark olive 
to dark brown, with dark mottling; often with 2 dark, 
oblique saddle marks under anterior and posterior 
parts of the second dorsal fin (especially evident in 
young); lower region of head and belly lighter to 
whitish. First dorsal fin darkly pigmented at base, 
with almost clear edge; remaining fins variously 
speckled, or banded as in the pectorals. 
  Breeding male dark overall, with a broad, reddish- 
orange edge on spinous dorsal fin; breeding female 
lighter overall, with distended abdomen. 
  Sexual dimorphism: Mature male with a subtrian- 
gular genital papilla, not present in female. 
In Wisconsin the slimy sculpin occurs in the Missis- 
sippi River, Lake Michigan, and Lake Superior 
drainage basins. In recent years this species has been 
discovered in isolated relict populations in the Mis- 
sissippi drainage in and near the driftless area. These 
populations, except for a few in Iowa and Minnesota 
tributaries to the Mississippi, appear to be widely re- 
moved from the rest of the species' range in the Great 
Lakes drainage and throughout Canada. 
  In 1964, slimy sculpins were collected from Citron 
Creek (Crawford County) by M. Johnson and were 
sent to the University of Michigan Museum of Zool- 
ogy for verification (Becker 1966). During July and 
August 1969, M. Johnson collected this species from 
11 sites in southwestern Wisconsin-at 4 locales in 
the upper Coon Creek system (Vernon and Monroe 
counties); 1 locale on Rush Creek (Crawford County), 
a tributary to the Mississippi River; 4 tributaries to 
the Kickapoo River (Crawford, Vernon, and Rich- 
land counties); and 2 locales in the Green River sys- 
tem (Grant County). In 1975, this species was taken 
with the mottled sculpin in Rock Creek (Barron 

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