The Effects of Water Temperature and Simulated Angling on the Physiological Stress Response of Largemouth Bass

The Largemouth Bass Micropterus salmoides, a popular sport fish, is subjected to multiple sublethal stressors during angling, including high water temperature, exercise, handling, live-well retention, and weigh-in procedures. Combined effects of ambient temperatures on the stress response recovery from angling-induced exercise have not been tested in conditions similar those encountered tournaments. Therefore, we assessed temperature (17, 25, 33°C) differential (?4, 0, +4°C) physiological (mean length = 331 mm) at rest, following simulated angling stressor, throughout 8 h live wells. Stress variables were measured whole blood (hematocrit, hemoglobin, pH, partial pressure oxygen [pO2], carbon dioxide [pCO2], Na+, K+, Ca2+, Cl?, leukocytes) plasma (cortisol, glucose, lactate, osmolality). Fish acclimated 17°C showed greatest cortisol after chasing stressor; however, higher levels pCO2, monocyte percentage found 33°C, lymphocyte lower 33°C than 17°C. When was manipulated, highest fish coldest (acclimated retained 13°C wells) warmest condition 37°C wells). However, all colder extremes survived, whereas 100% mortality occurred condition. Besides cortisol, indicators less pronounced temperatures. Glucose, notably K+ concentrations wells, Cl? lowest. Low lymphocytes monocytes indicate reduced immunocompetence or inflammation. Mortality may result exhaustion aerobic anaerobic energy sources, failure recover metabolic acidosis, an inability regain ionic balance.