Implications of size-selective fisheries on sexual selection.

Silva Uusi‐Heikkilä

doi:10.1111/eva.12988

Abstract

Fisheries often combine high mortality with intensive size selectivity and can, thus, be expected to reduce body size and size variability in exploited populations. In many fish species, body size is a sexually selected trait and plays an important role in mate choice and mate competition. Large individuals are often preferred as mates due to the high fecundity and resources they can provide to developing offspring. Large fish are also successful in competition for mates. Fisheries‐induced reductions in size and size variability can potentially disrupt mating systems and lower average reproductive success by decreasing opportunities for sexual selection. By reducing population sizes, fisheries can also lead to an increased level of inbreeding. Some fish species avoid reproducing with kin, and a high level of relatedness in a population can further disrupt mating systems. Reduced body size and size variability can force fish to change their mate preferences or reduce their choosiness. If mate preference is genetically determined, the adaptive response to fisheries‐induced changes in size and size variability might not occur rapidly. However, much evidence exists for plastic adjustments of mate choice, suggesting that fish might respond flexibly to changes in their social environment. Here, I first discuss how reduced average body size and size variability in exploited populations might affect mate choice and mate competition. I then consider the effects of sex‐biased fisheries on mating systems. Finally, I contemplate the possible effects of inbreeding on mate choice and reproductive success and discuss how mate choice might evolve in exploited populations. Currently, little is known about the mating systems of nonmodel species and about the interplay between size‐selective fisheries and sexual selection. Future studies should focus on how reduced size and size variability and increased inbreeding affect fish mating systems, how persistent these effects are, and how this might in turn affect population demography.

Highlights

The high mortality and size selectivity imposed by many commercial and recreational fisheries may negatively affect population productivity, as small fish typically have low fecundity and reproductive success (Barneche, Robertson, White, & Marshall, 2018; Shelton, Sinclair, Chouinard, Mohn, & Duplisea, 2006; Uusi-Heikkilä et al, 2015)
But often neglected, factor contributing to reproductive success in exploited fish populations is intersexual and intrasexual selection
Body size plays an important role in sexual selection in numerous fish species, as females may prefer large males who are superior in male–male competition and have high resource-holding potential (Huntingford & Turner, 1987; Järvi, 1990; Parker, 1974; van den Berghe & Gross, 1989)

Summary

Introduction

The high mortality and size selectivity (i.e., removal of large individuals) imposed by many commercial and recreational fisheries may negatively affect population productivity, as small fish (subjected to low fishing mortality) typically have low fecundity and reproductive success (Barneche, Robertson, White, & Marshall, 2018; Shelton, Sinclair, Chouinard, Mohn, & Duplisea, 2006; Uusi-Heikkilä et al, 2015). Body size plays an important role in sexual selection in numerous fish species, as females may prefer large males who are superior in male–male competition and have high resource-holding potential (Huntingford & Turner, 1987; Järvi, 1990; Parker, 1974; van den Berghe & Gross, 1989).

Results

Conclusion