Angling-induced cardiac disturbance of free-swimming largemouth bass (Micropterus salmoides) monitored with heart rate telemetry

The sub-lethal effects of catch-and-release angling have been poorly studied because of the difficulties in monitoring physiological parameters in free-swimming fish. Laboratory studies provide the opportunity to examine sub-lethal effects in controlled environments, but do not incorporate site-specific characteristics. In this study we angled free-swimming largemouth bass (Micropterus salmoides) equipped with heart rate transmitters to exhaustion using rod and reel, and exposed fish to air for 30 s. Experiments were repeated at four water temperatures (13, 17, 21, and 25degreesC). These field data were compared with published findings from largemouth bass collected at the same water temperatures in a controlled laboratory setting using Doppler flow probes. Field collected heart rate data increased with increasing water temperatures (Q(10) values 1.30-1.37). Pre-disturbance heart rates were similar to30% higher for free-swimming fish in the field than previously collected laboratory data at the same water temperatures. Fish angled in the field exhausted similar to40% more rapidly than fish chased in the laboratory. Maximal heart rate was similar to15% higher for free-swimming fish in the field than for data collected from laboratory restrained fish, but scope for heart rate was reduced by up to 20% in the field, especially at higher water temperatures. Heart rate in free-swimming fish was highly variable at all times, obscuring clear recovery patterns. Conversely, laboratory cardiac parameters exhibited less variable patterns, peaking clearly following disturbances and recovering in about 135 min, independent of water temperature. Based upon these findings, we suggest that comprehensive studies incorporating both laboratory and field experiments are needed for truly understanding the effect of catch-and-release angling on fish.