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Intense habitat-specific fisheries-induced selection at the molecular Pan I locus predicts imminent collapse of a major cod fishery.

Arnason E, Hernandez UB, Kristinsson K - PLoS ONE (2009)

Bottom Line: We hypothesize a potential collapse of the fishery.We find that probabilistic maturation reaction norms for Atlantic cod at Iceland show declining length and age at maturing comparable to changes that preceded the collapse of northern cod at Newfoundland, further supporting the hypothesis.We speculate that immediate establishment of large no-take reserves may help avert collapse.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biology, University of Iceland, Reykjavík, Iceland. einararn@hi.is

ABSTRACT
Predation is a powerful agent in the ecology and evolution of predator and prey. Prey may select multiple habitats whereby different genotypes prefer different habitats. If the predator is also habitat-specific the prey may evolve different habitat occupancy. Drastic changes can occur in the relation of the predator to the evolved prey. Fisheries exert powerful predation and can be a potent evolutionary force. Fisheries-induced selection can lead to phenotypic changes that influence the collapse and recovery of the fishery. However, heritability of the phenotypic traits involved and selection intensities are low suggesting that fisheries-induced evolution occurs at moderate rates at decadal time scales. The Pantophysin I (Pan I) locus in Atlantic cod (Gadus morhua), representing an ancient balanced polymorphism predating the split of cod and its sister species, is under an unusual mix of balancing and directional selection including current selective sweeps. Here we show that Pan I alleles are highly correlated with depth with a gradient of 0.44% allele frequency change per meter. AA fish are shallow-water and BB deep-water adapted in accordance with behavioral studies using data storage tags showing habitat selection by Pan I genotype. AB fish are somewhat intermediate although closer to AA. Furthermore, using a sampling design covering space and time we detect intense habitat-specific fisheries-induced selection against the shallow-water adapted fish with an average 8% allele frequency change per year within year class. Genotypic fitness estimates (0.08, 0.27, 1.00 of AA, AB, and BB respectively) predict rapid disappearance of shallow-water adapted fish. Ecological and evolutionary time scales, therefore, are congruent. We hypothesize a potential collapse of the fishery. We find that probabilistic maturation reaction norms for Atlantic cod at Iceland show declining length and age at maturing comparable to changes that preceded the collapse of northern cod at Newfoundland, further supporting the hypothesis. We speculate that immediate establishment of large no-take reserves may help avert collapse.

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Catch (tons), effort and catch per unit effort, CPUE, at year for different gear.Data are from log book records. Parts of these data are the same as figures 9.3.1. and 9.3.2 in [62]. Units of effort for different gear are described in Methods.
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pone-0005529-g003: Catch (tons), effort and catch per unit effort, CPUE, at year for different gear.Data are from log book records. Parts of these data are the same as figures 9.3.1. and 9.3.2 in [62]. Units of effort for different gear are described in Methods.

Mentions: Annual catch, effort, and catch per unit effort for different gear show a complex interaction with each other and with quotas and TACs (Figure 3 and Figure S7). The stock reached an all time low population numbers in 1993–1995 [27] (Figure S7). In the following years the MRI estimated an increase in numbers and increased quotas were issued. Catches of most gear increased and increased effort followed immediately or with a lag (of up to one year) for some gear. Both catch and effort peaked around 2000 and 2001. Catch per unit effort peaked earlier. Catch and effort of both long line and hand line started to increase later than other gear and peaked later or in 2004 and decreased somewhat after that (Figure 3). This, at least partly, accounts for the relative increase of catch by long line in the total catch (Figure S6). As catch diminished after reaching a peak, effort was reduced more rapidly and thus the relative measure of catch per unit effort increased. Using the relative measure of catch per unit effort as an indicator of stock abundance must take total catch into account and whether it is increasing or decreasing [28].


Intense habitat-specific fisheries-induced selection at the molecular Pan I locus predicts imminent collapse of a major cod fishery.

Arnason E, Hernandez UB, Kristinsson K - PLoS ONE (2009)

Catch (tons), effort and catch per unit effort, CPUE, at year for different gear.Data are from log book records. Parts of these data are the same as figures 9.3.1. and 9.3.2 in [62]. Units of effort for different gear are described in Methods.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2682699&req=5

pone-0005529-g003: Catch (tons), effort and catch per unit effort, CPUE, at year for different gear.Data are from log book records. Parts of these data are the same as figures 9.3.1. and 9.3.2 in [62]. Units of effort for different gear are described in Methods.
Mentions: Annual catch, effort, and catch per unit effort for different gear show a complex interaction with each other and with quotas and TACs (Figure 3 and Figure S7). The stock reached an all time low population numbers in 1993–1995 [27] (Figure S7). In the following years the MRI estimated an increase in numbers and increased quotas were issued. Catches of most gear increased and increased effort followed immediately or with a lag (of up to one year) for some gear. Both catch and effort peaked around 2000 and 2001. Catch per unit effort peaked earlier. Catch and effort of both long line and hand line started to increase later than other gear and peaked later or in 2004 and decreased somewhat after that (Figure 3). This, at least partly, accounts for the relative increase of catch by long line in the total catch (Figure S6). As catch diminished after reaching a peak, effort was reduced more rapidly and thus the relative measure of catch per unit effort increased. Using the relative measure of catch per unit effort as an indicator of stock abundance must take total catch into account and whether it is increasing or decreasing [28].

Bottom Line: We hypothesize a potential collapse of the fishery.We find that probabilistic maturation reaction norms for Atlantic cod at Iceland show declining length and age at maturing comparable to changes that preceded the collapse of northern cod at Newfoundland, further supporting the hypothesis.We speculate that immediate establishment of large no-take reserves may help avert collapse.

View Article: PubMed Central - PubMed

Affiliation: Institute of Biology, University of Iceland, Reykjavík, Iceland. einararn@hi.is

ABSTRACT
Predation is a powerful agent in the ecology and evolution of predator and prey. Prey may select multiple habitats whereby different genotypes prefer different habitats. If the predator is also habitat-specific the prey may evolve different habitat occupancy. Drastic changes can occur in the relation of the predator to the evolved prey. Fisheries exert powerful predation and can be a potent evolutionary force. Fisheries-induced selection can lead to phenotypic changes that influence the collapse and recovery of the fishery. However, heritability of the phenotypic traits involved and selection intensities are low suggesting that fisheries-induced evolution occurs at moderate rates at decadal time scales. The Pantophysin I (Pan I) locus in Atlantic cod (Gadus morhua), representing an ancient balanced polymorphism predating the split of cod and its sister species, is under an unusual mix of balancing and directional selection including current selective sweeps. Here we show that Pan I alleles are highly correlated with depth with a gradient of 0.44% allele frequency change per meter. AA fish are shallow-water and BB deep-water adapted in accordance with behavioral studies using data storage tags showing habitat selection by Pan I genotype. AB fish are somewhat intermediate although closer to AA. Furthermore, using a sampling design covering space and time we detect intense habitat-specific fisheries-induced selection against the shallow-water adapted fish with an average 8% allele frequency change per year within year class. Genotypic fitness estimates (0.08, 0.27, 1.00 of AA, AB, and BB respectively) predict rapid disappearance of shallow-water adapted fish. Ecological and evolutionary time scales, therefore, are congruent. We hypothesize a potential collapse of the fishery. We find that probabilistic maturation reaction norms for Atlantic cod at Iceland show declining length and age at maturing comparable to changes that preceded the collapse of northern cod at Newfoundland, further supporting the hypothesis. We speculate that immediate establishment of large no-take reserves may help avert collapse.

Show MeSH
Related in: MedlinePlus