The role of boldness and cortisol responsiveness in determining vulnerability to angling in a popular sportfish species

Recent work suggests that fisheries-induced selection may act ondirectly on behavioral characteristics in addition to life history traits.These behavioral tendencies, which may include correlated levels ofboldness and activity as well as underlying stress-hormoneresponsiveness, are often referred to as "behavioral syndromes" or"stress coping styles". It was the goal of this study to measureboldness and cortisol responsiveness to stress in largemouth bassMicropterus salmoides taken from an experimental populationselected for differential vulnerability to angling, and to determine ifthese traits influenced the likelihood of capture. Fish were subjectedto an open-field test to evaluate boldness, then had blood drawn todetermine levels of plasma cortisol in response to an air-exposurechallenge. The fish were then stocked into an experimental pondwhere a week-long series of angling sessions took place. Binarylogistic regression modelling was run following these trials toevaluate the effects of fish size, selected line, boldness, andbaseline/post-stress cortisol levels on the probability of capture. Ofthese, post-stress cortisol levels emerged as a significant negativepredictor of whether the fish was captured (p{\textless}.03). Cortisol levels(baseline and post-stress) were not correlated with boldness levels inbass in this study. Our findings that fish with higher post-stresscortisol levels were less likely to be captured provides furtherevidence that fisheries-induced selection may act on behavior andphysiology in addition to life-history traits.