Behavioural consequences of fisheries-induced evolution and their potential for population recovery

Fishing commonly targets large more valuable individuals, while small less valuable ones remain in the sea. By selecting the most profitable individuals, fishermen reduce chances that these valuable individuals pass their genes to next generations, a prax is that any animal breeder would consider counterproductive. Moreover, selective fishing leads to changes in life history traits (e.g., maturation, growth), which has repercussion for stock biomass and economic yield. At the UiB we are currently studying the consequences of size-selective fishing mortality on life history traits in nine experimental populations of guppies. Initial results show that our fishing regime that removes large individuals leads to slower growth and earlier maturation, as life his tory theory predicts. However, little is known on which other traits are affected by selective fishing. Changes in behaviour are the first response to human-induced environmental change, and have been suggested to be a key aspect in the interplay between ecology, evolution, conservation, and management. Moreover, fisheries can selectively remove specific behaviours (e.g., removal of less fearful individuals or more active ones) from a population, which can have implications for conservation and fishery pr oductivity. Fisheries scientists mostly overlook this behavioural dimension of fishing impact, and knowledge on its consequences is required. Thus, in collaboration with the University of California Davis we aim to address how fishing affects fish behavio ur. We will study behavioural traits under natural selection (anti-predator response) and behaviours related to adaptation to novel conditions (cognition and stress coping). We will compare the behavioural traits of the experimentally harvested population s from UiB and the wild-type populations present at UC Davis, which have been size-selected by natural predators.