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degrees; these diurnal changes were constant among stations. By subtracting the Green River temperature above the confluence from the Yampa River temperature, we found that the maximum temperature differential was about 6 to 7 C during the time that fish larvae were entering the Green. That difference was still 4 - 5 C at the site of the downstream recorder. The river conditions in 1984 would not have caused cold shock deaths. If conditions in other years change so that the temperature differences increases another 3 or 4 degrees, then the shock could cause behavioral changes that might lead to increased mortality from other secondary causes. We are continuing to analyze river temperature data from other years which show greater temperature differences between the two rivers than were found in 1984 (Miller et at. 1984). Miller et al. (1984) stated that: "Records provided by the Bureau of Reclamation and our collections indicated that in 1979, 1-980, and 1981, the temperature differences between the Yampa and Green River,-before mixing at Echo Park in August, were: 0 C (8-9-79), 1.5 C (8-8-80), and 1.5 C (8-5-81), respectively. -These were years when relative abundance of Colorado squawfish in the Green River was high. On August 4, 1983, however, a temperature differential of 10 C (16.2 F) was recorded at this location. Figure 14 provides temperature records for Flaming Gorge from 1979-83, and it can be seen that the temperature in 1983, apparently a very poor year for YOY Colorado squawfish, was also the lowest released in July and August from 1979 to 83." To predict temperature changes that might cause.direct mortality, a w nomograph published by Coutant in 1977 can be used (Figure 6). Note that our 15 C average mortality, where about 40% of our fish died, is in the "lethal" portion of the graph, while our 10 C average is comfortably on the safe side. a226PrR.crb Page 5