Fisheries‐induced evolution of alternative male life history tactics in Coho salmon

Abstract

Fisheries‐induced evolution (FIE) can result when harvest imposes artificial selection on variation in heritable phenotypic traits. While there is evidence for FIE, it remains difficult to disentangle the contributions of within‐generation demographic adjustment, phenotypic plasticity, and genetic adaption to observed changes in life history traits. We present evidence for FIE using dozens of Coho salmon (Oncorhynchus kisutch) populations in which males adopt one of two age‐invariant, heritable life history tactics: most mature as large three‐year‐old “hooknose” and typically fight for spawning opportunities, while some mature as small two‐year‐old “jacks” and fertilize eggs through sneaking. The closure of a fishery targeting three‐year‐old fish provided an experimental test of the prediction that fishery‐imposed selection against hooknose males drives an evolutionary increase in the proportion of males adopting the jack tactic. The data support the prediction: 43 of 46 populations had higher jack proportions during than after the fishery. The data further suggest that changes in jack proportion were not solely the result of demographic adjustments to harvest. We suggest that systems where fisheries differentially exploit phenotypically discrete, age‐invariant life histories provide excellent opportunities for detecting FIE.

Stochastic recruitment alters the frequencies of alternative life histories in age‐structured populations

“…Rather, increased mortality of hooknose males does inflate the relative abundance of jacks on the spawning grounds, but the number of fertilizations actually achieved by jacks does not increase proportionally due to FDS, mediating the population's realized evolutionary response to harvest. This may explain why documented increases in the prevalence of jacks in exploited salmon populations are uncommon despite long histories of size‐selective fisheries and extensive long‐term monitoring data (but see DeFilippo et al., 2019; Young et al., 2020). Importantly, this result emphasizes that frequency‐dependent mating (and sexual selection more broadly; Hutchings & Rowe, 2008) can filter how populations respond to fisheries‐induced selection and that measurements of frequency‐dependence (Berejikian et al., 2010) may be useful for predicting how alternative male life histories will respond to fishing or environmental change.…”

From the woods to the halls of science: Louis Bernatchez’s contributions to science, wildlife conservation and people

“…The authors invited to contribute to this Special Issue include both junior and senior researchers in the broad field of evolutionary/ecological/conservation genomics, reflecting the persistent mentoring to which Louis has constantly devoted so much time and energy (Figure 2). It is worthwhile to note that several of the papers detail long‐term research projects (Bowles, Marin, Mogensen, MacLeod, & Fraser, 2020; Garant, 2020; Perrier, Rougemont, & Charmantier, 2020; Stanford, Clake, Morris, & Rogers, 2020; Veliz et al, 2020), or collective advancements of a research group (Blanchet et al., 2020; Dalziel et al., 2020; Østbye et al, 2020), along with new “perspectives” and approaches in the field (Angers, Perez, Menieucci, & Leung, 2020; Durand et al., 2020; Filteau & Derôme, 2020; Gagnaire, 2020; Hallin et al., 2020; Lu et al., 2020; Milot, Béchet, & Maris, 2020; Sutherland et al., 2020), and the use of genomics information for wildlife management and conservation (Bangs, Douglas, Brunner, & Douglas, 2020; Bourret, Albert, April, Côté, & Morissette, 2020; Capblancq, Després, & Mavárez, 2020; Delrieu‐Trottin et al., 2020; Leblanc et al, 2020; Uusi‐Heikkilä, 2020; Young, Cluney, & Weir, 2020) as well as human health (Wirth, Wong, Vandenesch, & Rasigade, 2020).…”

“…It is this specific focus of science which he passed on to his students and ranges from an understanding of evolutionary processes such as connectivity and species boundaries to wildlife management and aquaculture (Figure 2). Most of the studies presented are based on wild populations, with a great majority of them focusing on fish (Angers et al., 2020; Bangs et al., 2020; Blanchet et al., 2020; Bowles et al., 2020; Dalziel et al., 2020; Delrieu‐Trottin et al., 2020; Gagnaire, 2020; Leblanc et al., 2020; Lu et al., 2020; Østbye et al, 2020; Stanford et al., 2020; Uusi‐Heikkilä, 2020; Veliz et al, 2020; Young et al., 2020), but also other aquatic organisms (Sutherland et al., 2020), as well as birds and mammals (Garant, 2020; Yannic, Hagen, Leugger, Karger, & Pellissier, 2020), terrestrial invertebrates (Capblancq et al, 2020), plants (Durand et al., 2020), yeast (Hallin et al., 2020) and bacteria (Filteau & Derôme, 2020; Wirth et al., 2020).…”

“…I discussed my thoughts with Louis and convinced him that structural genomic variation has been underappreciated, yet that this type of variation contributes to large amounts (and often even more so than SNP variants) of genomic variation (Catanach, Deng, Deng, Charles, Bernatchez, & Wellenreuther, 2019), and that we have an urgent need Specifically, systems where fisheries differentially exploit phenotypically discrete, age-invariant life histories provide particularly excellent candidates for detecting fisheries-induced evolution, and two contributions make that their focus. Young et al (2020) argue that fishery imposed selection against hook nose in males, a life-history trait in coho Salmon (Oncorhynchus kisutch), drives an evolutionary increase in the proportion of males adopting the jack tactic. They conclude that harvest-induced genetic changes may arise within 1-2.5 generations in these long-lived wild fishes, demonstrating the need to investigate concerns about harvest-induced evolution quickly once they have been raised.…”

Marine food web perspective to fisheries‐induced evolution

“…In the last decades, the evidence on FIE has been presented and challenged several times (Andersen & Brander, 2009 ; Browman et al, 2008 ; Jørgensen et al, 2007 ; Kuparinen & Merilä, 2007 ; Pinsky et al, 2021 ), ever since the seminal study on Arcto‐Norwegian cod, demonstrating the selective force of age‐specific harvest (Law & Grey, 1989 ). Notwithstanding remaining debates and challenges, to this day, a mounting body of literature indicates that FIE is supported not only theoretically but also empirically (Alós et al, 2014 ; Jakobsdóttir et al, 2011 ; Uusi‐Heikkilä et al, 2015 ; Young et al, 2020 ). However, while we are becoming more familiar with the consequences that FIE can have on population dynamics of a single species (Dunlop et al, 2015 ; Enberg et al, 2010 ; Hollins et al, 2018 ; Hutchings & Fraser, 2008 ; Kuparinen & Merilä, 2007 ), we are just beginning to grasp the array and intensity of its far‐reaching effects on the dynamics of the entire marine food webs.…”