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<br />decrease, the greater the mortality (Burton et al. 1979, Speakman and Krenkel <br />1972, Griffith 1978). <br />We suspect that mortality of 2-week-old larvae would be greater in the wild <br />because the fish shocked with 10 and 15 C decreases exhibited behavioral changes <br />that might have been lethal. Observers of cold shock kills caused by power <br />plant shutdowns have reported that stunned fish are stranded or covered, and <br />preyed upon by birds and other unaffected fish. We observed that fish shocked <br />with the 15 C drop lost equilibrium, floated with the current in the test. <br />aquaria, and ultimately settled to the bottom. Those shocked with 10 C did not <br />loose equilibrium, but did reduce their level of activity and occupied lower <br />portions of the water column than did control fish. These behavioral changes <br />are well documented in the literature and have been termed "cold coma", a <br />physiological state relating to osmoregulatory dysfunction and cessation of <br />opercular movement (Doudoroff 1942, Allanson et al. 1971). <br />The 19-day-old fish gained 9-10 mm during the course of the 26 day study, <br />with fish shocked at 10 and 15 C drops gaining about 1 mm less than controls <br />(Figure 4). This decrease is probably insignificant, but analyses are not yet <br />complete. The 72-day old fish gained only about 4 mm during the course of the <br />study, with no downward trend at greater temperature decreases. <br />A map of the confluence of the Green with the Yampa and the location of <br />Ryan thermographs placed in the rivers by Mr. Rick Jones, USFWS, Vernal, who <br />supplied temperature data to us, is shown in Figure 5. The mean noon-time water <br />temperatures above and below the confluence were monitored from 12 July to 9,, <br />August 1984 (Table 3). Daily temperaturg fluctuation at each site was 2 <br />a226PrR.crb Page 4