Darwinian fisheries science needs to consider realistic fishing pressures over evolutionary time scales

Worldwide depletion of fish stocks has led fisheries managers to become increasingly concerned about rebuilding and recovery planning. To succeed, factors affecting recovery dynamics need to be understood, including the role of fisheries-induced evolution. Here we investigate a stock's response to fishing followed by a harvest moratorium by analyzing an individual-based evolutionary model parameterized for Atlantic cod Gadus morhua from its northern range, representative of long-lived, late-maturing species. The model allows evolution of life-history processes including maturation, reproduction, and growth. It also incorporates environmental variability, phenotypic plasticity, and density-dependent feedbacks. Fisheries-induced evolution affects recovery in several ways. The first decades of recovery were dominated by demographic and density-dependent processes. Biomass rebuilding was only lightly influenced by fisheries-induced evolution, whereas other stock characteristics such as maturation age, spawning stock biomass, and recruitment were substantially affected, recovering to new demographic equilibria below their preharvest levels. This is because genetic traits took thousands of years to evolve back to preharvest levels, indicating that natural selection driving recovery of these traits is weaker than fisheries-induced selection was. Our results strengthen the case for proactive management of fisheries-induced evolution, as the restoration of genetic traits altered by fishing is slow and may even be impractical.

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“…2007) and in other models (Favro et al. 1979; Brown et al. 2008; Hilborn and Minte‐Vera 2008; Dunlop et al.…”

Section: Discussionmentioning

confidence: 86%

ORIGINAL ARTICLE: Implications of fisheries‐induced evolution for stock rebuilding and recovery

Enberg

Jørgensen

Dunlop

et al. 2009

Evolutionary Applications

214

258

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“…In general, theoretical models predict less of an evolutionary response to harvesting if fishing mortality is lower (Law and Grey 1989; Ernande et al. 2004; Brown et al. 2008).…”

Section: Introductionmentioning

confidence: 99%

ORIGINAL ARTICLE: Size‐selective fishing gear and life history evolution in the Northeast Arctic cod

Jørgensen¹,

Ernande²,

Fiksen³

2009

Evolutionary Applications

111

132

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Industrial fishing has been identified as a cause for life history changes in many harvested stocks, mainly because of the intense fishing mortality and its size-selectivity. Because these changes are potentially evolutionary, we investigate evolutionarily stable life-histories and yield in an energy-allocation state-dependent model for Northeast Arctic cod Gadus morhua. We focus on the evolutionary effects of size-selective fishing because regulation of gear selectivity may be an efficient management tool. Trawling, which harvests fish above a certain size, leads to early maturation except when fishing is low and confined to mature fish. Gillnets, where small and large fish escape, lead to late maturation for low to moderate harvest rates, but when harvest rates increase maturation age suddenly drops. This is because bell-shaped selectivity has two size-refuges, for fish that are below and above the harvestable size-classes. Depending on the harvest rate it either pays to grow through the harvestable slot and mature above it, or mature small below it. Sustainable yield on the evolutionary time-scale is highest when fishing is done by trawling, but only for a small parameter region. Fishing with gillnets is better able to withstand life-history evolution, and maintains yield over a wider range of fishing intensities.

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“…The examples presented in this study reveal the potential of Barcoding data for rapid evaluation of diversity and, in a larger scope, for comparative studies of genetic diversity in different ecological settings [17]. Although DNA barcoding may not be sufficient to rigorously address population-level questions [24], it may be an ideal tool for early detection of genetic depletion of exploited species.…”

Section: Discussionmentioning

confidence: 96%

Beyond Biodiversity: Fish Metagenomes

2011

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Biodiversity and intra-specific genetic diversity are interrelated and determine the potential of a community to survive and evolve. Both are considered together in Prokaryote communities treated as metagenomes or ensembles of functional variants beyond species limits.Many factors alter biodiversity in higher Eukaryote communities, and human exploitation can be one of the most important for some groups of plants and animals. For example, fisheries can modify both biodiversity and genetic diversity (intra specific). Intra-specific diversity can be drastically altered by overfishing. Intense fishing pressure on one stock may imply extinction of some genetic variants and subsequent loss of intra-specific diversity. The objective of this study was to apply a metagenome approach to fish communities and explore its value for rapid evaluation of biodiversity and genetic diversity at community level.Here we have applied the metagenome approach employing the Barcoding target gene COI as a model sequence in catch from four very different fish assemblages exploited by fisheries: freshwater communities from the Amazon River and northern Spanish rivers, and marine communities from the Cantabric and Mediterranean seas.Treating all sequences obtained from each regional catch as a biological unit (exploited community) we found that metagenomic diversity indices of the Amazonian catch sample here examined were lower than expected. Reduced diversity could be explained, at least partially, by overexploitation of the fish community that had been independently estimated by other methods.We propose using a metagenome approach for estimating diversity in Eukaryote communities and early evaluating genetic variation losses at multi-species level.

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Darwinian fisheries science needs to consider realistic fishing pressures over evolutionary time scales

Cited by 33 publications

References 27 publications

ORIGINAL ARTICLE: Implications of fisheries‐induced evolution for stock rebuilding and recovery

ORIGINAL ARTICLE: Implications of fisheries‐induced evolution for stock rebuilding and recovery

ORIGINAL ARTICLE: Size‐selective fishing gear and life history evolution in the Northeast Arctic cod

Beyond Biodiversity: Fish Metagenomes

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