What can selection experiments teach us about fisheries-induced evolution?

Abstract

There is evidence that fisheries are altering the phenotypic composition of fish populations, often in ways that may reduce the value of fish stocks for the exploiters. Despite the increasing number of theoretical and field studies, there is still debate as to whether these changes are genetic, can be reversed, and are occurring rapidly enough to be considered in fisheries management. We review the contribution that selection experiments have already provided with respect to the study of the evolutionary effect of fisheries, identify issues that still require more study, and outline future directions for doing so. Selection experiments have already been crucial in showing that harvesting can lead to phenotypic and genetic evolution over relatively short time frames. Furthermore, the experiments have shown the changes involve many other traits than those under direct selection, and that these changes tend to have population-level consequences, including a decreasing fisheries yield. However, experiments focused on fisheries-induced evolution that fulfil all our requirements are still lacking. Future studies should have more controlled and realistic set-ups and assess genetic changes in maturation and growth (i.e. traits most often reported to change) to be more relevant to exploited populations in the wild.

The evolutionary legacy of size‐selective harvesting extends from genes to populations

“…Controlled laboratory environment and a specific harvesting design allowed controlling for size‐dependent and other parental and epigenetic effects. This helped us to establish unambiguous cause (size‐selective harvesting)‐and‐effect (phenotypic and genetic changes) relationships (Diaz Pauli and Heino ) reinforcing the possibility that intensive harvesting of wild populations can indeed lead to fisheries‐induced evolution (FIE). Despite introducing obvious simplifications by maintaining discrete generations and allowing only single reproductive events, our selection experiment has value because it allowed the assessment of various phenotypic traits ranging from life‐history traits to physiology and behavior and applying a genomic approach to discover specific genes under selection.…”

“…; Uusi‐Heikkilä et al. ; Diaz Pauli and Heino ). Several, not mutually exclusive, mechanisms may be at play.…”

“…). In theory, experiments on FIE could also be designed in the wild (McAllister and Peterman ), but the cause‐and‐effect mechanism of size‐selective harvesting can best be studied experimentally in controlled laboratory environments (Conover and Baumann ; Diaz Pauli and Heino ). However, to date, only few experimental studies have conclusively reported harvest‐induced genetic changes based on quantitative genetics (Conover and Munch ; Philipp et al.…”

Marine growth patterns of southern British Columbia chum salmon explained by interactions between density-dependent competition and changing climate

“…Although beyond the scope of this study, decreases to body size in harvested fish species have also been the result of intensive and selective fishing in natural and experimental populations (Hard et al 2008;Diaz-Pauli and Heino 2014). Fisheries that select older or larger size classes can cause directional selection away from older or larger maturation of age because these fish experience greater mortality (Trippel 1995;Law 2000;Marshall and Browman 2007).…”

The effects of marine protected areas over time and species' dispersal potential: a quantitative conservation conflict attempt

“…However, in general there are several behavioural changes in fishers after establishing an MPA (e Costa et al, 2013). While it would be interesting to know whether landings attain the levels observed before the implementation of MPAs (convex curves for high dispersal distance) and how long this will take, other acting processes such as increased fishing pressure (García-Rubies et al, 2013) or phenotypic evolution (Diaz Pauli and Heino, 2014;Moustakas and Evans, 2013) also occur, thus long-term outputs are unlikely to be realistic. Thus, the model was only run long enough to discern some variability between species' dispersal abilities.…”