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9 <br />Mortality was higher in 7 of 8 of the 1984 treatments on 14-day old fish <br />than in 1985, possibly indicating that supersaturation may have been a <br />problem. Death of 40-day-old fish subjected to all shocks was similar to <br />controls, and substantially lower in all cases than that of 14-day-old <br />fish. <br />Fish shocked with 10 and 15 C decreases in 5 minutes exhibited <br />behavioral changes. Those shocked by the 15 C drop were briefly <br />hyperactive, and then lost equilibrium, floated with the current in the <br />test aquaria, or settled to the bottom. Ninety-six percent of the <br />mortality in these tanks occurred in the first 48 hours. Those shocked by <br />the 10 C decrease in 5 minutes did not loose equilibrium but did reduce <br />activity and occupied lower portions of the water column than did control <br />fish for about 14 hours. Deaths of fish exposed to 5 and 10 C decreases in <br />5 minutes occurred randomly over the duration of the experiment rather than <br />in the first 48 hours as observed in tanks where the temperature was <br />lowered 15 C. <br />Temperature shock had no significant effect on the growth of 40-day-old <br />fish, which grew 3.1-4.7 mm during the experiment (Table 2). Althouqh one- <br />way analysis of variance indicated significant growth in 3 of 4 experiments <br />on 14-day-old fish, there were no apparent trends. For example, fish <br />stocked by a 10 C decrease in 5 minutes in 1984 were longer than controls <br />at the end of the experiment, whereas those shocked by 5 and 15 C decreases <br />were shorter. Dead fish were removed and not replaced, hence the number of <br />fish per aquaria varied and may have influenced growth. Better growth of <br />14-day-old fish in 1984 compared to 1985 is evidence aqainst saturation <br />beinq much of a problem in 1984, and agreed with growth rates observed by <br />Hammon (1981). The difference between years could have been due to