Thermal tolerance of lake sturgeon
Wilkes, Paul Andrew
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Habitat restoration has allowed management agencies to begin reintroducing lake sturgeon (Acipenser fulvescens) into the Coosa River of Georgia and Alabama; however, high summer temperatures may preclude establishment of a self-sustaining population. In this study, we estimated the critical thermal maxima of 200 days post-hatch (DPH) and 400 DPH lake sturgeon. The 400 DPH age group had the lowest critical thermal maxima; they lost equilibrium at 35.1°C when acclimated at 24.9°C and at 33.1°C when acclimated to 18.1°C. To assess the effects of prolonged exposure to high temperature on lake sturgeon, we subjected groups of lake sturgeon to four increasing temperature regimes of 26°C, 29°C, 32°C and 35°C. When exposed to temperatures above the ULSTLT (31.7°C), feed consumption was reduced by 20-35% and weight gain was negligible. At temperatures near the CTM (35.1°C), feeding rate decreased to near zero. Prolonged exposure of lake sturgeon to temperatures near their CTM resulted in mortality of all individuals.