Working Group on Fisheries Induced Evolution (WGEVO; outputs from 2022)

The Working Group on Fisheries Induced Evolution (WGEVO) progressed on its three main objectives, namely: (i) assembling and reviewing empirical evidence of fisheries-induced evolution; (ii) developing tools for scientists and managers to monitor and mitigate fisheries-induced evolution and its consequences for fisheries; and (iii) estimating fisheries-induced Darwinian selection pressures in exploited stocks.

During the term, the primary focus of the group has been the estimation of fisheries-induced Darwinian selection pressure (FISP) on exploited stocks’ life history traits, with development of methods, support tools for users, and FISP estimation conducted on a sample of stocks distributed worldwide. WGEVO further developed the estimation procedure of fisheries-induced Darwinian selection pressures on exploited stocks’ life-history traits (somatic growth, maturation traits and reproductive effort). The methodological update refines the established estimation procedure for some of the relevant parameters and allows to obtain estimates of covariance among selected traits based on available stock data. The updated procedure is applied to 58 stocks inhabiting freshwater and marine environments, from pelagic, bentho-pelagic and benthic habitat.

The main findings emerging from the analyses show that on average, fishing induces statistically significant selection pressures towards earlier maturation at smaller size, reduced growth, and increased reproductive effort. Across stocks, fisheries-induced selection pressures align along two nearly independent axes: a growth axis describing negatively covarying pressures on somatic and gonadic growth, and a maturation axis describing pressures on maturation. WGEVO performed analyses aimed at identifying the main determinants of selection pressures’ strength within three broad categories: fishing characteristics, natural mortality characteristics and species life-history. R scripts for applying the framework developed and a R notebook to be used as user guide have been updated according to the revised procedures.