The metabolic and biochemical basis of vulnerability to recreational angling after three generations of angling-induced selection in a teleost fish

Although the selective pressures of commercial fishing are well known, few studies have examined this phenomenon in recreational fisheries. This study used a unique population of largemouth bass (Micropterus salmoides) with lines bred for low (LVF) and high (HVF) vulnerability to recreational angling. We evaluated whether differential vulnerability to angling was correlated with physiological traits, including metabolic rate, metabolic scope, anaerobic capacity, and biochemical response to exercise. Indeed, angling selection affected the metabolic rate of fish significantly. The standard metabolic rate was 10%, maximal metabolic rate was 14%, and metabolic scope was 16% lower for LVF compared with HVF. Following exhaustive exercise, LVF required 1 h for lactate levels to recover to control values, whereas HVF required 2 h. Anaerobic energy expenditure was significantly lower for LVF, a finding consistent with the observation that LVF swam at a steadier rate during exercise. Although the reasons behind vulnerability to angling are complex, the phenotypic trait "vulnerability to angling" appears to be linked to a suite of physiological traits, including metabolism and the capacity for anaerobic activity. Thus, angling-induced selection might alter the physiological characteristics of wild largemouth bass populations, with unknown outcomes for long-term population viability.