Effective stocking programs are an essential part of maintaining most high-quality tributary steelhead Oncorhynchus mykiss fisheries in the Great Lakes, requiring sufficient numbers of stocked fish to survive, imprint, and return as adults. New York’s Lake Erie tributaries have long supported popular and economically important recreational steelhead fisheries, attracting anglers from across the country. Recent research has illustrated New York’s dependence on “stray” steelhead from other jurisdictions, making New York fisheries vulnerable to other agencies’ management decisions. We hypothesized that the limited contribution by New York-stocked steelhead was attributable to poor poststocking survival and imprinting due to the smaller stocking size relative to other Lake Erie jurisdictions. We took an experimental approach to describe how the combination of stocking size and within-stream stocking location interact to influence emigration and adult returns and identify mechanisms that may be driving these relationships, with the goal of identifying stocking strategies that improve adult returns. Stocked steelhead >150 mm total length emigrated from the stream by the end of May; small-size steelhead tended to remain in the stream and exhibited upstream migration. The residual population of steelhead lost body condition and likely experienced high mortality. Adult returns from large-size fish that were stocked 6.4 km upstream were 4.1 times greater than small-size fish stocked upstream and six times greater than fish stocked near the lake confluence (0.8 km upstream). We conclude that many of the steelhead stocked by New York are too small to imprint and emigrate, instead remaining as stream residents that experience poor survival and ultimately make minimal contributions to the adult fishery. Increases in the stocking size of New York steelhead coupled with stocking well upstream of the lake confluence would result in increased adult returns of New York-stocked fish to their streams of origin and improved fishery performance and resiliency.

中文翻译：

---

虹鳟放养规模和位置对迁徙和成年返回的影响

有效的放养计划是维持大多数优质支流虹鳟Oncorhynchus mykiss的重要组成部分大湖区的渔业，需要足够数量的放养鱼才能生存、留下印记并成年后返回。纽约的伊利湖支流长期以来一直支持着受欢迎且经济上重要的休闲虹鳟渔业，吸引了来自全国各地的垂钓者。最近的研究表明，纽约对来自其他司法管辖区的“流浪”虹鳟的依赖，使得纽约渔业容易受到其他机构的管理决策的影响。我们假设纽约放养的虹鳟的有限贡献归因于放养后的存活率和印记，因为相对于其他伊利湖辖区而言，放养规模较小。我们采用实验方法来描述放养规模和流内放养位置的组合如何相互作用以影响移民和成人回报，并确定可能推动这些关系的机制，目的是确定提高成人回报的放养策略。到 5 月底，从溪流中移出的总长度大于 150 毫米的放养钢头；小型钢头倾向于留在溪流中并表现出上游迁移。剩余的虹鳟种群失去了身体状况，并可能经历了高死亡率。在上游 6.4 公里处放养的大型鱼的成鱼产量是上游放养的小型鱼的 4.1 倍，是在湖泊汇合处（上游 0.8 公里）附近放养的鱼的 6 倍。我们得出的结论是，纽约放养的许多虹鳟鱼太小而无法留下印记和移民，而是作为溪流居民而生存，他们的生存能力很差，最终对成年渔业做出的贡献微乎其微。纽约虹鳟放养规模的增加以及湖泊汇合处上游的放养井将导致纽约放养鱼的成鱼返回其原产地溪流并提高渔业绩效和恢复力。