PREFERRED HABITATS OF SLIMY AND MOTTLED SCULPIN IN 
COLDWATER TRIBUTARIES OF THE UPPER MISSISSIPPI RIVER, 
SOUTHEASTERN MINNESOTA

Neal Mundahl, Kristin Nelson, Michael Harnung, and Sarah Hach
Department of Biology, Winona State University, Winona, MN 55987

Habitat use and preferred habitats of slimy (Cottus cognatus) and mottled (Cottus bairdi) 
sculpin were examined in five coldwater tributaries of the Upper Mississippi River in 
southeastern Minnesota.  Availability and sculpin use of substrate type, water depth, and 
bottom current velocity were assessed to determine habitat preferences for both young-
of-year (YOY) and adult sculpin.  Most (>70%) individuals of both species (slimy n = 
777, mottled n = 100) used coarse substrates and vegetation, shallow water (< 30 cm), 
and slow current velocities (<20 cm/sec).  Adults of both species preferred boulder 
substrate, whereas YOY preferred gravel and rubble.  Slimy sculpin YOY and adults also 
preferred vegetation, but mottled sculpin did not.  Mottled sculpin YOY and adults 
preferred shallower water (0-20 cm) than slimy YOY (0-30 cm) or adults (10-50 cm).  
Slimy YOY and adults and mottled YOY preferred slower bottom velocities (0-30 
cm/sec) than mottled adults (20-40 cm/sec).  Preferred substrates, depths, and current 
velocities were all found together (ideal habitat) at >15% of individual points surveyed in 
the streams.  Two streams where slimy sculpin were recently reintroduced contained <8% 
ideal habitat, but another contained >18%.  Sections of two streams that had been 
improved for trout habitat had one-third less ideal sculpin habitat than nearby, 
unimproved sections of the same streams, primarily the result of more deep (>60 cm) 
water in improved sections.  To improve success, future sculpin reintroductions should 
focus on coldwater streams that have >10% ideal sculpin habitat.

Keywords: sculpin, preferred habitats, coldwater streams, Cottus