Abstract Broodstock collection and enhancement programs are a widely-used management practice within the Atlantic salmon's (Salmo salar) native range. Wild-origin adult salmon captured as part of these programs experience multiple stressors during their time in hatcheries. However, no studies have assessed the potential consequences of hatchery practices on the physiology (stress and immune states), migratory behaviour, and long-term survival of hatchery-spawned kelts that are subsequently released back to their natal river. To address these knowledge gaps, we obtained blood samples from, and acoustically tagged 30 hatchery-spawned kelts and 31 wild-spawned kelts, originating from endangered populations native to a UNESCO Biosphere Reserve in Canada during the autumns of 2014 and 2015. We then tracked individuals for up to two years through their downstream river migration, estuarine residence, ocean entry, and subsequent return as repeat-spawners. Our results indicated that hatchery-spawned kelts showed significantly higher stress levels (elevated plasma cortisol and glucose), as well as potentially altered immune states (increased circulating prostaglandin E2) in comparison to wild-spawned individuals. Behaviourally, hatchery-spawned kelts exited freshwater prematurely (~66 days earlier on average) compared to wild-spawned counterparts, which was associated with a marked increase in estuarine mortality. Furthermore, survival to repeat-spawning was 0% (0/30) for hatchery-spawned kelts and 6.5% (2/31) for wild-spawned. Given that female repeat-spawners are generally larger and have increased fecundity, our findings suggest that a reduction in the fitness of post-spawners and likelihood of repeat-spawning as a result of hatchery stressors could have population-level consequences. Such impacts should be considered in conservation and management planning.

中文翻译：

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圈养繁殖的后果：野生来源、孵化场产卵的大西洋鲑鱼返回野外后的健康影响

摘要 亲体采集和增殖计划是大西洋鲑鱼（Salmo salar）原生范围内广泛使用的管理实践。作为这些计划的一部分捕获的野生成年鲑鱼在孵化场期间会遇到多种压力。然而，没有任何研究评估孵化场实践对孵化场产生的 kelts 的生理学（压力和免疫状态）、洄游行为和长期存活的潜在影响，这些 kelts 随后被释放回它们的出生河流。为了解决这些知识空白，我们在 2014 年和 2015 年秋季从加拿大联合国教科文组织生物圈保护区的濒危种群中获取了 30 只孵化场产生的 kelts 和 31 只野生产生的 kelts 的血液样本并对其进行了声学标记。然后，我们通过下游河流迁徙、河口居住、海洋进入以及随后作为重复产卵者的返回对个体进行了长达两年的追踪。我们的结果表明，与野生繁殖的个体相比，孵化场繁殖的 kelts 表现出显着更高的压力水平（血浆皮质醇和葡萄糖升高），以及潜在的免疫状态改变（循环前列腺素 E2 增加）。在行为上，与野生产卵的同类相比，孵化场产的海带过早离开淡水（平均提前约 66 天），这与河口死亡率显着增加有关。此外，重复产卵的存活率为孵化场产卵的 0% (0/30) 和野生产卵的 6.5% (2/31)。鉴于雌性重复产卵者通常较大且繁殖力增加，我们的研究结果表明，由于孵化场压力因素导致产卵后适应性降低和重复产卵的可能性可能会对种群水平产生影响。在保护和管理规划中应考虑此类影响。