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

Abstract

Sublethal 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.

Received October 27, 2011; accepted September 9, 2012

ACKNOWLEDGMENTS

We thank M. J. Diana, L. Einfalt, and J. Wisher of the Kaskaskia Biological Station, who assisted with organization, field, and laboratory work. M. Carey, C. Deboom, Z. Blevins, A. Gingerich, B. Olds, A. Pope, and S. Landsman assisted with field work. M. Garthaus, S. Pallo, and J. Ferencak helped coordinate activities with the Illinois Department of Natural Resources (IDNR). The Ron Ward Memorial Scholarship awarded by the Champaign-Urbana Bass Club, and the Graduate Student Conservation Scholarship awarded by the Bass Anglers Sportsman's Society (B.A.S.S.), and Costa del March provided financial support to M. M. V. This project was supported in part by the IDNR, Division of Fisheries, through Federal Aid in Sportfish Restoration Project F-135-R and by the U.S. Department of Agriculture Cooperative State Research Education and Extension Service by McIntire–Stennis funds through project ILLU-875-328. We also thank the organizers and participants of the Ever-Bloom Tournament Trail, especially T. Brown and M. Blake, for their participation in the study. The Lake Bloomington Police and the staff of the McLean County Parks Department and Comlara Park, especially M. Steffa and B. Wasson, provided logistical support.