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16 Additionally, these data agree with observations of squawfish response to cold shock made by staff members at Dexter National Fish Hatchery, who have cultured squawfish for several years (Hamman 1981; 1985). Most reports conclude that the faster the rate of temperature decrease, the greater the mortality (Speakman and Kuenkel 1972, Burton et al. 19799 Griffith 1978). This relationship was evident when comparing squawfish response to abrupt and gradual 15 C decreases in this study. Effects of fish age also seem important since the 40-day old larvae were unaffected by temperature decreases imposed in this study. Young of other species are usually more sensitive than adults (Pitkow 1960, Nickum 1966), probably because their change in body temperature is more rapid than that of larger fish. Elliott (1981) found that 1000 g rainbow trout required 23-35 minutes to change body temperature after water temperature was lowered 10 C; change in small fish was rapid. However, difference in body weight between 14- and 40-day-old squawfish was.probably unimportant, and resistance to cold shock in older fish was more likely due to their greater pysiological ability to adapt. The changes in squawfish behavior were typical of those exhibited by other species when shocked with sudden temperature decreases. The "stunned" behavior has been termed "cold coma" and is a physiological state relating to osmoregulatory dysfunction and cessation of opercular movement (Doudoroff 1942, Pitkow 1960, Allanson et al, 1971). The fish that recovered from coma after shocks of 10 and 15 C in this study would probably not have done so in the wild. Observers of fish kills caused by cold shock have reported that stunned fish become stranded in shallows where they were easily preyed upon by birds and unaffected fish. Uneaten fish that settle to the bottom can become covered with settling solids