Reconstructing the effects of fishing on life-history evolution in North Sea plaice Pleuronectes platessa

Abstract

Growing evidence suggests that fishing may induce rapid contemporary evolution in certain life-history traits. This study analyzes fisheries-induced changes in life-history traits describing growth, maturation, and reproduction, using an individual-based eco-genetic model that captures both the population dynamics and changes in genetic trait values. The model was successfully calibrated to match the observed life-history traits of female North Sea plaice Pleuronectes platessa around the years 1900 and 2000. On this basis, we report the following findings. First, the model indicates changes in 3 evolving life-history traits: the intercept of the maturation reaction norm decreases by 27%, the weight-specific reproductive-investment rate increases by 10%, and the weight-specific energy-acquisition rate increases by 1%. Together, these changes reduce the weight at maturation by 46% and the asymptotic body weight by 28% relative to the intensification of fishing around 1900. Second, while the maturation reaction norm and reproductive-investment rate change monotonically over time, the energy-acquisition rate follows a more complex course: after an initial increase during the first 50 yr, it remains constant for about 30 yr and then starts to decline. Third, our analysis indicates that North Sea plaice has not yet attained a new evolutionary equilibrium: it must be expected to evolve further towards earlier maturation, increased reproductive investment, and lower adult body size. Fourth, when fishing continues in our model 100 yr into the future, the pace of evolution slows down for the maturation reaction norm and the rate of en ergy acquisition, whereas no such slowing down is expected for the rate of reproductive investment.

Spatio-temporal patterns and environmental controls of small pelagic fish body condition from contrasted Mediterranean areas

“…A more likely process relies on the catchability that is often size and condition-dependent. Indeed, fisheries-induced selection is known to magnify shifts toward young, small and more quickly maturing individuals in targeted populations (Devine et al, 2012;Audzijonyte et al, 2013a;Mollet et al, 2016, Kuparinen et al, 2016, but difficulties remain in distinguishing phenotypical responses from true evolutionary changes. Phenotypic plasticity deals with the adaptive response of an organism faced with fishing pressure and/or changing environment.…”

Major changes in sardine growth and body condition in the Bay of Biscay between 2003 and 2016: Temporal trends and drivers

“…Fisheries-induced selection is commonly known to significantly impact biological traits of exploited populations such as changes in population demography, decreases in size-at-age or earlier maturation (Ernande et al, 2004;Grift et al, 2003;Marty et al, 2015;Mollet et al, 2016). One of the reasons for the age-dependent decrease in body length could therefore be the result of the fishery becoming more and more size-selective to ensure an appropriate supply to both the canning industry and consumers.…”

The use of spatial management tools in rights‐based groundfish fisheries

“…This might be due to the fact that one of the stronger outcomes was recovery of age structure, a benefit that takes longer to accrue and contribute to productivity. However, other indicators of the health of the plaice stock such as length‐at‐maturity have continued to decline (Mollet, Dieckmann, & Rijnsdorp, ). Like the Scotian Shelf and North Sea, Namibia effectively employs a single closed area rather than a distributed network.…”

“…However, other indicators of the health of the plaice stock such as length-at-maturity have continued to decline (Mollet, Dieckmann, & Rijnsdorp, 2016). Like the Scotian Shelf and North Sea, Namibia effectively employs a single closed area rather than a distributed network.…”