Mortality of Largemouth Bass during Catch-and-Release Tournaments in a Puerto Rico Reservoir

Abstract

In Puerto Rico, unique protocols are used during fishing tournaments for largemouth bass Micropterus salmoides. Live wells are not required, and many anglers retain their catch on metal stringers. During day tournaments, fish are collected and weighed by a roving weigh-in boat; night tournaments use a central weigh-in station. We monitored 15 fishing tournaments over 1 year in Lucchetti Reservoir, Puerto Rico, to quantify mortality rates and to evaluate the impact of tournaments on the adult fish population. Initial mortality was documented at weigh-in, and delayed mortality was determined by holding largemouth bass for 4 d in floating mesh pens with control (electrofished) largemouth bass. Initial and delayed mortality averaged 8% (range, 0–38%) and 43% (10–98%), respectively. The delayed mortality rate was adjusted by the control mortality rate (mean, 7%; range, 0–50%) for each tournament to yield adjusted delayed mortality rate (mean, 36%; range, 10–68%), which we used to calculate total mortality rate (mean, 42%; range, 13–68%). Although surface water temperature ranged only between 23°C and 28°C, total mortality was significantly lower (P ≤ 0.05) during January–February, being positively correlated with temperature. Night tournaments experienced significantly greater total mortality rates than day tournaments, most likely because of the eightfold longer retention of bass before weigh-in during night tournaments. Retention time was positively correlated with initial mortality rates. We estimated that tournament mortality removed 6% of the adult largemouth bass population and accounted for 23% of all fishing mortality. We recommended reducing tournament fishing during hotter, high-mortality periods; modification of night tournaments; and use of well-maintained live wells. Combined with angler education, such modifications of tournament procedures can reduce the impact of tournaments in tropical reservoirs.