Substrate 



Substrate composition appeared to be an important habitat 

 parameter influencing the distribution, and possibly the 

 abundance, of sculpin species found at any one particular sampled 

 reach. However, there were no clear distinctions between 

 species. 



Several explanations have been offered to explain the affinity of 

 sculpins for rubble substrates. Interstitial spaces which are 

 common in rubble substrates offer refuge from predatory fish and 

 birds. Sculpin typically attempted to escape the electroshocker 

 by burrowing into the substrate. In addition, rubble substrates 

 typically support higher concentrations of aquatic insects which 

 are thought to be the primary food source for sculpin. (Gangemi 

 1992, p36) Additionally, this survey found that sculpin 

 seemingly favor cover, shadows, low light intensity, and darker 

 colored substrate. When displaced from cover, sculpin would 

 typically dart away upstream to evade the disturbance. They 

 would then hold momentarily until disturbed again, and double- 

 back to their approximate point of origin. Also, sculpin deposit 

 their adhesive eggs in a mass on the underside of cobbles 

 suspended above the stream bottom, and do not typically have a 

 lengthy (longitudinal) range within a lotic habitat (Scott and 

 Grossman 1973) . 



Torrent sculpin appeared more capable of tolerating habitat with 

 some degree of finer substrate material than the slimy sculpin. 

 This may, in fact, be an indirect measure of some other habitat 

 parameter influencing torrent distribution (i.e. torrent might 

 prefer warmer stream temperatures, slower velocities, or lower 

 gradients typical of larger-order reaches) . 



Temperature 



Temperatures appear to exhibit some influence on species 

 distribution although species specific tolerance ranges were not 

 determined in this study. Torrent sculpin were typically found 

 at sites with warmer stream temperatures. Slimy sculpin appeared 

 to prefer sites with slightly cooler temperature ranges than did 

 the torrent sculpin (i.e. torrent might prefer warmer stream 

 temperatures, slower velocities, or lower gradients typical of 

 larger-order reaches) . 



23 



