The successful use of remote site incubators (RSIs) to rear eggs of Arctic Grayling Thymallus arcticus along Montana streams has sparked interest in reestablishing the species in Michigan. As a preparatory step, we assessed the efficacy of RSIs by deploying them along three Michigan streams during 2 years using surrogate eggs from Rainbow Trout Oncorhynchus mykiss. Our objectives were to (1) compare hatching success between two different RSI designs (19‐L versus 265‐L RSIs), (2) test whether the removal of dead eggs (“picking”) from 19‐L RSIs affected hatching success, and (3) develop a simple model to predict fry yield and its uncertainty. Overall survival was 41.3% in 2018 and 52.4% in 2019. Differences in survival between unpicked 19‐L and 265‐L RSIs tended to be small, with mean differences from 4.82% (95% CI = –0.60 to +10.25) in 2018 to 0.08% (95% CI = –0.14 to +0.30) in 2019. On average, picked 19‐L RSIs had greater, although not always statistically significant, survival than unpicked 19‐L RSIs during both years (mean difference = 1.6% [2018] and 10.4% [2019]). We documented a significant positive correlation between survival and RSI flow rate. Survival abruptly declined in unpicked 19‐L RSIs when RSI flow rates dropped below ~0.3 L/min, suggesting that removing dead eggs from 19‐L RSIs likely increased survival when RSI flow rates were <0.3 L/min. The most notable result from our fry yield model was that increasing the number of RSIs reduced the coefficient of variation in fry yield following a pattern of diminishing returns, suggesting two or three RSIs usually will be a good choice. We showed that 19‐L and 265‐L RSIs can be used successfully in Michigan streams, with our model providing a tool for managers to explore the relative importance of several properties of RSI design and operation on fry yield and uncertainty.

中文翻译：

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评估密歇根州河流中的偏远地区孵化器：对北极河鳟重新引入的启示

成功地使用远程站点孵化器（RSI）沿蒙大纳州溪流饲养北极河鳟Thymallus arcticus的卵，引起了人们对在密歇根州重建该物种的兴趣。作为准备步骤，我们通过使用Rainbow Trout Oncorhynchus mykiss的代卵在2年内沿密歇根州的三条溪流部署RSI来评估RSI的功效。我们的目标是（1）比较两种不同RSI设计（19-L与265-L RSI）之间的孵化成功率，（2）测试从19-L RSI中清除死卵（“拣选”）是否会影响孵化成功， （3）建立一个简单的模型来预测鱼苗的产量及其不确定性。总体存活率在2018年为41.3％，在2019年为52.4％。未拣选的19-L和265-L RSI之间的存活率差异较小，2018年的平均差异为4.82％（95％CI = –0.60至+10.25）。至2019年的0.08％（95％CI = –0.14至+0.30）。平均而言，在过去两年中，精选的19-L RSI的存活率均高于未挑选的19-L RSI（均值= 1.6％） [2018]和10.4％[2019]）。我们记录了生存率和RSI流量之间的显着正相关。当RSI流速降至〜0.3 L / min以下时，未采摘的19 L RSI的存活率突然下降，这表明当RSI流速<0.3 L / min时，从19 L RSI清除死卵可能会提高存活率。我们的鱼苗产量模型最显着的结果是，随着收益递减模式的出现，增加RSI数量会减少鱼苗产量的变异系数，这表明通常使用两个或三个RSI是一个不错的选择。我们证明了19 L和265 L RSI可以在密歇根州的河流中成功使用，我们的模型为管理人员提供了一种工具，可用来探索RSI设计和操作的若干属性对鱼苗产量和不确定性的相对重要性。我们的鱼苗产量模型最显着的结果是，随着收益递减模式的出现，增加RSI的数量会减少鱼苗产量的变异系数，这表明通常使用两个或三个RSI是一个不错的选择。我们证明了19 L和265 L RSI可以在密歇根州的河流中成功使用，我们的模型为管理人员提供了一种工具，可用来探索RSI设计和操作的若干属性对鱼苗产量和不确定性的相对重要性。我们的鱼苗产量模型最显着的结果是，随着收益递减模式的出现，增加RSI数量会减少鱼苗产量的变异系数，这表明通常使用两个或三个RSI是一个不错的选择。我们证明了19 L和265 L RSI可以在密歇根州的河流中成功使用，我们的模型为管理人员提供了一种工具，可用来探索RSI设计和操作的若干属性对鱼苗产量和不确定性的相对重要性。