Does body size affect the response to exercise in shortnose sturgeon (Acipenser brevirostrum)?

Abstract

The effect of body size on various hematological variables was examined in juvenile shortnose sturgeon (Acipenser brevirostrum) ranging in mass from 38 to 730 g. The blood was examined for differences in plasma ionic composition (Na + , K + , Cl − ), blood oxygen carrying capacities (hemoglobin, hematocrit), and plasma metabolite concentrations (lactate, glucose), before and following a standard 5-min chasing stress. All measured resting hematological variables were size independent in shortnose sturgeon. After exercise, levels of plasma lactate, potassium, and hemoglobin increased in all fish. Only post-exercise levels of chloride and hemoglobin changed in a size-dependent manner; however, the relationships were weak. The general lack of a relationship between body size and hematological variables might reflect the narrow range of fish sizes used in the present study. From a practical perspective, the results suggest that when examining the hematological stress response in juvenile shortnose sturgeon, a range of fish sizes could be used. This is important considering the variability in the growth rates of juvenile shortnose sturgeon under laboratory conditions.