Abstract
Current debates about the efficacy of no‐take marine reserves (MR) in protecting large pelagic fish such as tuna and sharks have usually not considered the evolutionary dimension of this issue, which emerges because the propensity to swim away from a given place, like any other biological trait, will probably vary in a heritable fashion among individuals. Here, based on spatially explicit simulations, we investigated whether selection to remain in MRs to avoid higher fishing mortality can lead to the evolution of more philopatric fish. Our simulations, which covered a range of life histories among tuna species (skipjack tuna vs. Atlantic bluefin tuna) and shark species (great white sharks vs. spiny dogfish), suggested that MRs were most effective at maintaining viable population sizes when movement distances were lowest. Decreased movement rate evolved following the establishment of marine reserves, and this evolution occurred more rapidly with higher fishing pressure. Evolutionary reductions in movement rate led to increases in within‐reserve population sizes over the course of the 50 years following MR establishment, although this varied among life histories, with skipjack responding fastest and great white sharks slowest. Our results suggest the evolution of decreased movement can augment the efficacy of marine reserves, especially for species, such as skipjack tuna, with relatively short generation times. Even when movement rates did not evolve substantially over 50 years (e.g., given long generation times or little heritable variation), marine reserves were an effective tool for the conservation of fish populations when mean movement rates were low or MRs were large.
Highlights
Given the generalized fisheries-induced declines of marine biodiversity in the last decades (Watson et al, 2013), there is, among marine biologists, a wide agreement that marine protected areas (MPAs) and especially no-take marine reserves (MRs) are needed to avoid further biodiversity losses (Lubchenco, Palumbi, Gaines, & Andelman, 2003; Pauly et al, 2002; Wood, Fish, Laughren, & Pauly, 2008) and to regain what has been lost (Roberts, Hawkins, & Gell, 2005)
We predicted that the evolution of decreased movement rate following the establishment of marine reserves would lead to higher within-reserve population size relative to situations with no heritable variation in movement rate
For each species, for both levels of fishing mortality, we evaluated the effect of reserve number and movement distance on within-reserve population density and frequency of allele a 50 years after reserve establishment
Summary
Given the generalized fisheries-induced declines of marine biodiversity in the last decades (Watson et al, 2013), there is, among marine biologists, a wide agreement that marine protected areas (MPAs) and especially no-take marine reserves (MRs) are needed to avoid further biodiversity losses (Lubchenco, Palumbi, Gaines, & Andelman, 2003; Pauly et al, 2002; Wood, Fish, Laughren, & Pauly, 2008) and to regain (at least partly) what has been lost (Roberts, Hawkins, & Gell, 2005). | 445 in a single year (Bonfil et al, 2005; Sibert & Hampton, 2003), and reserves may afford protection only for a limited portion of a species’ life cycle, especially for migratory species (McAllister, Barnett, Lyle, & Semmens, 2015). Even within such species, variation exists, with many individuals displacing less than 50 nautical miles (NM) between tagging and recapture, and some displacing more than 1,000 NM (Sibert & Hampton, 2003). By neglecting the potential evolution of reduced movement rate following reserve establishment, managers may underestimate the efficacy of marine reserves
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