Experimental size-selective harvesting affects behavioral types of a social fish

Abstract

In most fisheries, larger fish experience substantially higher mortality than smaller fish. Body length, life-history and behavioral traits often correlate, such that fisheries-induced changes in size or life-history can also alter behavioural traits. However, empirical evidence regarding how size-selective harvesting alters the evolution of behavioural traits in exploited stocks is scarce. We used experimental lines of zebrafish (Danio rerio) that were exposed to positive, negative or random size-selective harvest over five generations. Our aim was to investigate whether simulated fishing changed the mean personality of the surviving females five generations after initial harvesting halted. We found that mean boldness, activity, and sociability were significantly altered relative to a randomly harvested control line. Harvestinduced changes in individual-level personality were only detected in the negatively sizeselected line. By contrast, we did not detect harvest-induced evolution of personality in the positively size-selected line. We conclude that size-selective harvesting alters individual fish personality in a social fish.