Consequences of fisheries-induced evolution for population productivity and recovery potential

Abstract

Fisheries-induced evolution has become a major branch of the research on anthropogenic and contemporary evolution. Within the conservation context, fisheries-induced evolution has been hypothesized to negatively affect the persistence and recovery potential of depleted populations, but this has not been explicitly investigated. Here, we investigate how fisheries-induced evolution of Atlantic cod (Gadus morhua L.) life histories affects per capita population growth rate, a parameter negatively correlated with extinction risk. We simulate the evolutionary and ecological dynamics of a cod population for a 100 year period of size-selective harvesting, followed thereafter by 300 years of recovery. To evaluate the relative importance of harvest-induced evolution, we either allowed life histories to evolve during and after the fishing period, or we assumed that fisheries-induced evolution was absent. Population growth rates did not differ appreciably between the evolutionary and non-evolutionary simulation scenarios, despite the emergence of rather pronounced differences in life histories. The underlying reason was that in the absence of fishing the cumulative lifetime reproductive outputs were very similar among differing life histories. The results suggest that fisheries-induced evolution might not always have as clear-cut an effect on population growth rate as previously anticipated.

Harvest-induced evolution: insights from aquatic and terrestrial systems

“…Owing to sharply lower population density, rapidly maturing phenotypes might have an initial advantage through shorter generation time and give the appearance of a faster initial recovery [45]. Eco-evolutionary simulations, however, suggest that fisheries-induced evolution is instead likely to have either negligible effects on population recovery rates at all abundances, due to flat fitness landscapes across alternative life histories [42,43,46], or negative effects through reduced juvenile production [47]. Notably, those fish populations that have shown phenotypic changes under intensive fishing have not recovered from overfishing even after a moratorium [48,49].…”

“…In addition, the fitness function may not always be bell-shaped as expected for traits with a single and clear optimal peak value. If the fitness function is relatively flat across a range of phenotypes [42], the ecological impacts of harvest-induced evolution will be reduced, but so will the rate of evolutionary recovery after the artificial selective pressure of intense harvest stops [2,43].…”

Genetic architecture of age at maturity can generate divergent and disruptive harvest-induced evolution

“…In the context of fisheries-induced evolution, predictions of fish life-history change are based on the assumption that life-history traits are inherited quantitatively, such that juvenile trait values are expected to be equal to the average of parental trait values. For example, virtually all eco-evolutionary simulations either model the inheritance of life-history traits through a large number of loci with additive effects [3,4] or through continuous trait values [5,6], and assuming that the heritability of the quantitative traits is approximately 0.2-0.3 [7]. These assumptions are sound and in accordance with general knowledge of the genetic basis of life-history traits [1,2].…”

Hormonal responsiveness to stress is negatively associated with vulnerability to angling capture in fish

“…The majority of these studies have focused on the alteration of life-history traits (Kuparinen and Hutchings, 2012), including decreases in growth rate, lower total reproductive output and reduced age at maturity in populations of marine species that have been subjected to commercial harvest (Devine et al, 2012;Kuparinen and Merilä, 2007). Similar processes may also be occurring in freshwater fisheries primarily targeted by recreational hook-and-line anglers (Kendall and Quinn, 2011;Nussle et al, 2009), which may reduce the overall fitness of individuals in the population (Sutter et al, 2012).…”