I tested the effects of different ration sizes on preferred temperatures of yearling lake charr, Salvelinus namaycush, by feeding them for about 2 weeks on one of four rations and then allowing them to thermoregulate in a temporal thermal gradient for 2 to 3 days. Selected temperatures and ration were directly and linearly correlated: the larger the ration, the higher the temperature selected. Mean preferred temperatures at different rations (shown in parentheses as percent of body weight per day) were as follows: 9.2A?C (0.3); 10.6A?C (0.8); 11.7A?C (2.0); and 12.6A?C (5.5). While the shift to lower temperature, under restricted ration, would maximize food conversion efficiency, previous growth studies indicate that even lower selected temperature would have been more beneficial.
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Effects of ration size on preferred temperature of lake charr Salvelinus namaycush