Upper Lethal Temperatures of Some British Columbia Freshwater Fishes

Abstract

During the summers of 1950 and 1951 the upper lethal temperature was measured for 14 species of freshwater fishes, representing five families. The fish were captured from lakes in the southern Okanagan Valley, and the experiments were conducted in the Summerland Trout Hatchery, Summerland, B.C. The upper temperature (°C.) at which 50 per cent of the fish died in 24 hours was estimated as follows, the approximate acclimation temperature being given in brackets: Salmo gairdneri kamloops fingerlings, 24.0(11); Oncorhynchus nerka kennerlyi fry, 22(11); Catostomus catostomus, 27(11.5), 26.6(14); Mylocheilus caurinus, 27(10), 27.1(14); Rhinichthys falcatus, 28.3(14); Richardsonius balteatus, 25(9–11), 27.6(14); Cottus asper, 24.1(18–19); Catostomus macrocheilus, 29.4(19); Micropterus salmoides, 28.9(20–21); Ptychocheilus oregonensis, 29.3(19–22); Ameiurus melas melas, 35.0(23); Perca flavescens, 26.5(18), 29.2(22–24); Lepomis glbbosus, 28.0(18), 30.2(24); Cyprinus carpio, 31–34(20), 35.7(26).