Artificial stream channels were used to study habitat choice, interspecific interactions, use of refugia, and locomotory activity of Pit sculpin, Cottus pitensis, marbled sculpin, C. klamathensis macrops, and rough sculpin, C. asperrimus, from the Pit River drainage, California. An attempt was made to determine whether these factors affected the distribution of these cottids, testing the following hypotheses: (1) Species do not differ in selection of depth, substrate, or cover type; (2) Species do not differ in the way in which they use refugia or in locomotory activity. When given a choice of deep (9 = 43 cm) or shallow (9 = 20 cm) water, the species differed in the percentage of individuals using deep water and were ranked rough sculpin (greatest use of deep water) > marbled sculpin > Pit sculpin. When offered a choice of sand or cobble substrate, all species chose cobble substrate more often than sand substrate; however, use of sand increased from marbled sculpin to rough sculpin to Pit sculpin. When given the choice of cobbles or plants as cover, the species did not exhibit a preference. Marbled sculpin used refugia most often, and there was a significant positive correlation between size of marbled sculpin and use of refugia. Pit sculpin were more active than marbled and rough sculpin. The results for depth selection were consistent with field studies, but those for substrate and cover were not. The difference in habitat choice and behavior among the species could not explain their field distribution. Differences in behavior among the species may result in differential vulnerability to predators in different habitat types. This may explain the absence of Pit sculpin from areas dominated by the other species.
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Larry R. Brown (1991) studied this question.