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Genetic assessment of a summer chum salmon metapopulation in recovery.

Small MP, Johnson TH, Bowman C, Martinez E - Evol Appl (2013)

Bottom Line: Following supplementation, differentiation among subpopulations decreased (but not significantly) and isolation by distance patterns remained unchanged.There was no decline in genetic diversity in wild-born fish, but hatchery-born fish sampled in the same spawning areas had significantly lower genetic diversity and unequal family representation.Despite potential for negative effects from supplementation programs, few were detected in wild-born fish.

View Article: PubMed Central - PubMed

Affiliation: Washington Department of Fish and Wildlife, Molecular Genetics Laboratory Olympia, WA, USA.

ABSTRACT
Programs to rebuild imperiled wild fish populations often include hatchery-born fish derived from wild populations to supplement natural spawner abundance. These programs require monitoring to determine their demographic, biological, and genetic effects. In 1990s in Washington State, the Summer Chum Salmon Conservation Initiative developed a recovery program for the threatened Hood Canal summer chum salmon Evolutionarily Significant Unit (ESU) (the metapopulation) that used in-river spawners (wild fish) for each respective supplementation broodstock in six tributaries. Returning spawners (wild-born and hatchery-born) composed subsequent broodstocks, and tributary-specific supplementation was limited to three generations. We assessed impacts of the programs on neutral genetic diversity in this metapopulation using 16 microsatellite loci and a thirty-year dataset spanning before and after supplementation, roughly eight generations. Following supplementation, differentiation among subpopulations decreased (but not significantly) and isolation by distance patterns remained unchanged. There was no decline in genetic diversity in wild-born fish, but hatchery-born fish sampled in the same spawning areas had significantly lower genetic diversity and unequal family representation. Despite potential for negative effects from supplementation programs, few were detected in wild-born fish. We hypothesize that chum salmon natural history makes them less vulnerable to negative impacts from hatchery supplementation.

No MeSH data available.


Plots of genetic statistics for samples grouped into original, hatchery, and wild categories. Genetic statistics are detailed in Tables 1 and 2.
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fig02: Plots of genetic statistics for samples grouped into original, hatchery, and wild categories. Genetic statistics are detailed in Tables 1 and 2.

Mentions: Genotypic coverage averaged 95% and ranged from 84% (One-106) to 97% (Oki-1) per locus over all individuals (N = 2086). Because samples (tissues and archived scales) were from spawner carcasses of varying freshness, genotyping success varied among samples, regardless of contemporary or historical status. In tests for Hardy–Weinberg equilibrium (HWE) at individual loci (Supplementary Information, Table S3), two tests out of 832 were significant after corrections for multiple tests and all samples except 08Salmon_W were in HWE in tests over all loci (Table 1). The Wilcoxon sign rank tests indicated no significant differences between original and wild-born samples in genetic diversity measures (gene diversity, allelic richness) or HmNe (Fig. 2, Table 3, see Tables 1 and 4 for individual collection values). However, hatchery-born spawners had lower genetic diversity and significantly lower HmNe than wild-born spawners (differences in genetic diversity were not significant when Dosewallips and Duckabush were excluded from wild samples but differences in HmNe between wild-and hatchery-born samples remained significant).


Genetic assessment of a summer chum salmon metapopulation in recovery.

Small MP, Johnson TH, Bowman C, Martinez E - Evol Appl (2013)

Plots of genetic statistics for samples grouped into original, hatchery, and wild categories. Genetic statistics are detailed in Tables 1 and 2.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3927888&req=5

fig02: Plots of genetic statistics for samples grouped into original, hatchery, and wild categories. Genetic statistics are detailed in Tables 1 and 2.
Mentions: Genotypic coverage averaged 95% and ranged from 84% (One-106) to 97% (Oki-1) per locus over all individuals (N = 2086). Because samples (tissues and archived scales) were from spawner carcasses of varying freshness, genotyping success varied among samples, regardless of contemporary or historical status. In tests for Hardy–Weinberg equilibrium (HWE) at individual loci (Supplementary Information, Table S3), two tests out of 832 were significant after corrections for multiple tests and all samples except 08Salmon_W were in HWE in tests over all loci (Table 1). The Wilcoxon sign rank tests indicated no significant differences between original and wild-born samples in genetic diversity measures (gene diversity, allelic richness) or HmNe (Fig. 2, Table 3, see Tables 1 and 4 for individual collection values). However, hatchery-born spawners had lower genetic diversity and significantly lower HmNe than wild-born spawners (differences in genetic diversity were not significant when Dosewallips and Duckabush were excluded from wild samples but differences in HmNe between wild-and hatchery-born samples remained significant).

Bottom Line: Following supplementation, differentiation among subpopulations decreased (but not significantly) and isolation by distance patterns remained unchanged.There was no decline in genetic diversity in wild-born fish, but hatchery-born fish sampled in the same spawning areas had significantly lower genetic diversity and unequal family representation.Despite potential for negative effects from supplementation programs, few were detected in wild-born fish.

View Article: PubMed Central - PubMed

Affiliation: Washington Department of Fish and Wildlife, Molecular Genetics Laboratory Olympia, WA, USA.

ABSTRACT
Programs to rebuild imperiled wild fish populations often include hatchery-born fish derived from wild populations to supplement natural spawner abundance. These programs require monitoring to determine their demographic, biological, and genetic effects. In 1990s in Washington State, the Summer Chum Salmon Conservation Initiative developed a recovery program for the threatened Hood Canal summer chum salmon Evolutionarily Significant Unit (ESU) (the metapopulation) that used in-river spawners (wild fish) for each respective supplementation broodstock in six tributaries. Returning spawners (wild-born and hatchery-born) composed subsequent broodstocks, and tributary-specific supplementation was limited to three generations. We assessed impacts of the programs on neutral genetic diversity in this metapopulation using 16 microsatellite loci and a thirty-year dataset spanning before and after supplementation, roughly eight generations. Following supplementation, differentiation among subpopulations decreased (but not significantly) and isolation by distance patterns remained unchanged. There was no decline in genetic diversity in wild-born fish, but hatchery-born fish sampled in the same spawning areas had significantly lower genetic diversity and unequal family representation. Despite potential for negative effects from supplementation programs, few were detected in wild-born fish. We hypothesize that chum salmon natural history makes them less vulnerable to negative impacts from hatchery supplementation.

No MeSH data available.