Temporal Variation in the Physiological Responses in Largemouth Bass following Small Club Angling Tournaments

Abstract

AbstractSublethal physiological disturbances and mortality were quantified in Largemouth Bass Micropterus salmoides subjected to small, club‐style angling tournaments (<30 teams) held at two central Illinois lakes. Between April and October, physiological disturbances were assessed in four tournaments at Lake Bloomington, and mortality was assessed in four tournaments at Evergreen Lake. Indicators of physiological disturbances were evident in Largemouth Bass following club angling tournaments, with some temporal variation in responses. Plasma glucose concentrations increased in tournament‐caught fish relative to reference fish in all months, except during October, when glucose concentrations did not change; plasma cortisol values among tournament fish also were lowest during October. Plasma potassium levels decreased only in April, whereas chloride levels were unaffected by tournaments. Sodium concentrations varied across months, but the magnitude of tournament‐induced decreases were similar across all months. Whole‐blood hemoglobin was lowest in May, and although hematocrit significantly decreased in tournament‐caught fish in May, it remained unchanged in other months. Lactate increases occurred during all tournaments and were of similar magnitudes even though water temperatures ranged from 15.7°C to 27.6°C. Small, yet significant, temporal differences were observed in plasma sodium and in whole‐blood hemoglobin concentrations from reference fish collected in each month via electrofishing, which indicated temporal changes in baseline values for some parameters. Mortality at tournaments was low (<5%) and did not appear to vary across months. Our results suggest that physiological responses of Largemouth Bass to small, club‐style tournaments can vary temporally and are similar to those sustained during professional tournaments, even if mortality rates are generally low.