Several largemouth bass Micropterus salmoides tournaments in Ontario were visited in the summers of 1999 and 2000 to examine the physiological changes that occur in largemouth bass as a result of tournament procedures. Physiological variables were compared among tournament‐caught largemouth bass, resting laboratory controls, and angled controls. The plasma cortisol and glucose concentrations and plasma osmolarity in tournament‐caught largemouth bass sampled within 5 min following the weigh‐in were significantly greater than those in both control groups. Tournament‐caught fish also exhibited ionic disturbances that involved increases in plasma sodium and potassium concentrations, but there were no significant changes in the levels of plasma chloride. Large changes in the metabolic status of largemouth bass sampled following the weigh‐in included major reductions in the muscle energy stores phosphocreatine, adenosine triphosphate, and glycogen and large increases in muscle and plasma lactate concentrations. In contrast, no significant changes occurred in the mRNA levels of heat‐shock protein 70 in several tissues or in plasma creatine phosphokinase activity. Taken together, these results indicate that live‐release angling tournaments cause a significant physiological disturbance in largemouth bass, but there is no evidence that these events normally result in serious cell damage.

This study combines laboratory experiments with temperature monitoring and fish sampling in the wild to determine if Atlantic salmon (Salmo salar) parr from the Miramichi River in New Brunswick are currently experiencing significant sublethal heat stress during the warm summer months. Laboratory experiments indicated that Hsp 70 mRNA and protein and Hsp 30 mRNA were all significantly induced in Atlantic salmon parr between 22°C and 25°C. Field sampling during moderate spring temperatures and a high-temperature event in summer further indicated that the threshold for mRNA induction of both Hsp 70 and Hsp 30 is around 23°C, but Hsp 70 protein levels were only significantly elevated in the field at 27°C. Hsc 70 mRNA and protein levels were not significantly increased during heat stress under laboratory conditions. In the field, however, Hsc 70 mRNA was significantly increased at 23°C and both Hsc 70 mRNA and protein levels were elevated at 27°C. Taken together, the results of this investigation suggest that Atlantic salmon parr from the Miramichi River are currently experiencing temperatures that will cause significant protein damage and induce a heat-shock response for about 30 days each summer.

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