Data from: Genetic assessment of a summer chum salmon metapopulation in recovery

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.旨在修复濒危野生鱼类种群的项目，通常会采用源自野生种群的孵化场繁育个体，以补充自然产卵亲体的种群规模。此类项目需要开展监测，以评估其种群统计、生物学及遗传学效应。20世纪90年代，美国华盛顿州的夏季狗鲑保护倡议（Summer Chum Salmon Conservation Initiative）针对受威胁的胡德运河夏季狗鲑进化显著单元（Evolutionarily Significant Unit, ESU，即集合种群）制定了恢复方案：在6条支流中，分别以河道内产卵的野生个体作为对应批次的补充亲鱼群；洄游产卵的亲体（包括野生个体与孵化场繁育个体）构成后续的亲鱼群，且各支流的增殖放流活动仅限定延续三代。 本研究基于16个微卫星位点（microsatellite loci）与覆盖增殖放流前后、跨度约8个世代的三十年数据集，评估了该集合种群的上述项目对中性遗传多样性的影响。结果显示，增殖放流后，亚种群间的遗传分化程度有所下降（但未达到显著水平），且距离隔离模式未发生改变；野生个体的遗传多样性未出现下降，但在相同产卵区域采样的孵化场繁育个体，其遗传多样性显著更低且家系代表不均一。 尽管增殖放流项目存在产生负面影响的潜在可能，但在野生个体中几乎未检测到此类影响。我们推测，狗鲑的自然生活史特征使其对孵化场增殖放流（hatchery supplementation）带来的负面影响具备更强的抵御能力。