Responses of a Freshwater Sculpin (Cottus cognatus gracilis) to Temperature

Abstract

Temperature tolerance, avoidance, and preference of a freshwater sculpin, Cottus cognatus gracilis, are described for fish acclimated to constant temperatures ranging from 5 to 20 C. Critical thermal maxima varied from 23.5 C for fish acclimated to 5 C, to 29.4 C for fish acclimated to 20 C. Incipient upper lethal temperatures ranged from 18.5 C to 23.5 C. The ultimate upper lethal temperature was approximately 26.5 C. Avoidance temperatures ranged from 15.2 C at 5 C to 21.5 C at 15 C. Preferred temperatures for 5 C- and 15 C-acclimated fish were 9 and 12 C, respectively, and the final preferendum was about 10 C.