The ability of native fish to establish self-sustaining populations when reintroduced to vacant habitats is variable. We evaluated factors that potentially affect the reintroduction success of juvenile Colorado River Cutthroat Trout Oncorhynchus clarkii pleuriticus that were reintroduced to an isolated watershed and were experiencing suboptimal survival and recruitment. We conducted a 3-year mark–recapture study to model annual apparent survival probability as it related to (1) different ex situ rearing strategies and (2) initial release among different habitat types. The use of PIT tags also enabled the quantification of loss via emigration. Apparent survival was highest for small fish that were minimally exposed to ex situ rearing conditions, stocked in small, headwater stream reaches. However, maximum estimates of apparent survival remained low (≤0.38 ± 0.05 [estimate ± SE]) regardless of rearing treatment, stocking location, or interactive effects between covariates. Emigration of stocked fish (<1%) from the study area did not appear to limit their establishment. Our results suggest that variation in stocking and rearing strategy may have some effect on translocation success and the interaction between rearing and stocking strategy highlights the importance of considering the life history stage of stocked individuals when identifying stocking sites. Consistently low annual survival values may be indicative of a larger issue, requiring in-depth evaluation of adaptive potential within our brood source and other factors that potentially limit population persistence.

中文翻译：

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放养的科罗拉多河切喉鳟鱼的运动动力学和生存

本地鱼类在重新引入空置栖息地时建立自给自足种群的能力是可变的。我们评估了可能影响科罗拉多河割喉鳟Oncorhynchus clarkii pleuriticus幼鱼重新引入成功的因素被重新引入到一个孤立的流域并且正在经历次优的生存和招募。我们进行了一项为期 3 年的标记-重新捕获研究，以模拟年度表观存活概率，因为它与 (1) 不同的异地饲养策略和 (2) 不同栖息地类型之间的初始释放有关。使用 PIT 标签还可以量化移民造成的损失。最小程度地暴露于异地养殖条件下，放养在小的源头溪流中的小鱼的表观存活率最高。然而，无论饲养处理、放养位置或协变量之间的交互作用如何，表观存活的最大估计值仍然很低（≤0.38 ± 0.05 [估计值 ± SE]）。研究区放养鱼的迁出 (<1%) 似乎并没有限制它们的建立。我们的结果表明，放养和饲养策略的变化可能对易位成功有一些影响，饲养和放养策略之间的相互作用突出了在确定放养地点时考虑放养个体生活史阶段的重要性。持续低的年存活值可能表明存在更大的问题，需要深入评估我们育雏源内的适应性潜力和其他可能限制种群持久性的因素。