ORIGINAL ARTICLE: Eco‐genetic model to explore fishing‐induced ecological and evolutionary effects on growth and maturation schedules

Abstract

Eco-genetic individual-based models involve tracking the ecological dynamics of simulated individual organisms that are in part characterized by heritable parameters. We developed an eco-genetic individual-based model to explore ecological and evolutionary interactions of fish growth and maturation schedules. Our model is flexible and allows for exploration of the effects of heritable growth rates (based on von Bertalanffy and biphasic growth patterns), heritable maturation schedules (based on maturation reaction norm concepts), or both on individual- and population-level traits. In baseline simulations with rather simple ecological trade-offs and over a relatively short time period (<200 simulation years), simulated male and female fish evolve differential genetic growth and maturation. Further, resulting patterns of genetically determined growth and maturation are influenced by mortality rate and density-dependent processes, and maturation and growth parameters interact to mediate the evolution of one another. Subsequent to baseline simulations, we conducted experimental simulations to mimic fisheries harvest with two size-limits (targeting large or small fish), an array of fishing mortality rates, and assuming a deterministic or stochastic environment. Our results suggest that fishing with either size-limit may induce considerable changes in life-history trait expression (maturation schedules and growth rates), recruitment, and population abundance and structure. However, targeting large fish would cause more adverse genetic effects and may lead to a population less resilient to environmental stochasticity.

Size‐selective fishing and the potential for fisheries‐induced evolution in lake whitefish

“…Indeed, evidence has emerged that fishing mortality of stocks, both marine and freshwater, can be sufficiently high for evolutionary changes in life history traits to occur at trackable, ecological timescales (Edeline et al., 2007; Heino et al., 2015; Jørgensen et al., 2007; Nusslé, Bornand, & Wedekind, 2009; Olsen et al., 2004). Further, the direction and intensity of fisheries‐induced selection are expected to depend on which sizes are targeted, either through size or gear restrictions (Dunlop, Heino, & Dieckmann, 2009; Hutchings, 2009; Jørgensen, Ernande, & Fiksen, 2009; Wang & Höök, 2009). For example, Jørgensen et al.…”

“…In eco‐genetic models of fisheries‐induced evolution of maturation traits in lake whitefish, somatic growth rate is assumed to be negatively density‐dependent according to a specified functional form. This allows for feedbacks between ecological and evolutionary processes in response to alternative forms and intensities of size‐selective fishing (Dunlop, Eikeset, & Stenseth, 2015; Dunlop, Heino et al., 2009; Wang & Höök, 2009). Eco‐genetic modeling also has been used to explore how different intensities of density‐dependent growth affect population dynamics and stock productivity (Gobin, Lester, Fox, & Dunlop, 2016).…”

Roles of density-dependent growth and life history evolution in accounting for fisheries-induced trait changes

“…First, although eco-evolutionary models have included density-dependent growth (24,(45)(46)(47)(48), previous evolutionary models of NEA cod (28,(49)(50)(51) did not, and thus could not assess the differential contributions of phenotypic plasticity and trait evolution to the observed maturation trends in this stock. Second, although some eco-evolutionary models have allowed simultaneous evolution of multiple traits (e.g., growth and maturation) (22,45,46,48,52), most previous studies restricted attention to the evolution of maturation schedules (51, 53-56); here, we consider an evolving maturation schedule in conjunction with the potential for fisheries-induced evolution in two other important life history traits, somatic growth and reproductive investment. Allowing for the simultaneous evolution of these additional traits might reduce the amount of evolution predicted in the maturation schedule, because the processes of growth, maturation, and reproductive investment are naturally intertwined.…”

A review of ecological models for brown trout: towards a new demogenetic model

“…In addition, forward-time simulation programs such as simu-POP and NEMO (Guillaume & Rougemont 2006) explicitly model the properties of individuals and specify arbitrary patterns of population size changes. In the field of quantitative genetics, the recent development of individual-based eco-genetic models allowed evaluating the relative importance of genetic and ecological effects on fish life-history traits and stock productivity by taking into account quantitative genetic traits inheritance (e.g., Dunlop et al 2009;Wang & Hook 2009).…”