Supplementing fish populations at the egg stage is a low‐cost alternative to hatchery rearing that is presumed to improve adaptation to local natural conditions. The Shoshone‐Bannock Tribes began supplementing Chinook Salmon Onchorynchus tschwytscha in Panther Creek, Idaho, at the eyed egg stage in 2014. The Chinook Salmon eggs were artificially fertilized and reared to eye‐up in the hatchery and then planted in custom‐made in‐stream incubators (egg boxes) for volitional release and natural rearing. Using data from three brood years, we evaluated the efficacy of this supplementation program solely in terms of juvenile production. We related juvenile production to the placement and retrieval of the egg boxes, assessed the relative contributions of offspring (parr and emigrants) from the egg boxes (HOR) to overall juvenile abundance, and compared the performance (length, condition, dispersal distance, and survival) of HOR versus natural‐origin (NOR) juveniles. Brood year and box placement within the stream (distance upstream) were the best predictors of whether or not an egg box was retrieved from its original location. Meanwhile, the condition of the box (i.e., intact, damaged, or missing) was the best single predictor of juvenile production. Supplemented eggs represented an estimated 42, 50, and 42% of the total egg deposition in Panther Creek in brood years 2014, 2015, and 2016, respectively. A parentage analysis revealed that the egg boxes accounted for 6, 22, and 35%, respectively, of the parr production for the respective brood years when the data were normalized to the estimated egg deposition—less than the egg‐to‐parr production that was estimated for natural redds. As fall parr, the HOR fish differed from the NOR fish in terms of their length and dispersal behavior, but they were of similar length and condition at their emigration from Panther Creek and exhibited no significant difference in downstream survival through the Federal Columbia River Power System (FCRPS). Collectively, our results provide useful insights to fisheries managers who are interested in initiating or refining egg supplementation programs.

中文翻译：

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流内卵孵化器生产的孵化场奇努克鲑鱼与天然幼鱼相似或不同

在蛋阶段补充鱼类种群是孵化场饲养的一种低成本替代方案，据信这可以提高对当地自然条件的适应性。肖肖尼-巴诺克部落开始补充奇努克鲑鱼Onchorynchus tschwytscha2014年在爱达荷州Panther Creek的带眼卵阶段。将奇努克鲑鱼卵人工受精，并在孵化场进行养眼，然后种植在定制的河内孵化器（蛋箱）中，以自愿释放和自然饲养。使用来自三个育雏年的数据，我们仅根据幼体产量评估了该补充计划的功效。我们将幼稚的生产与蛋箱的放置和取回相关，评估了蛋箱（HOR）的后代（parr和emimigrants）对总体幼鱼丰度的相对贡献，并比较了其性能（长度，状况，传播距离和生存率（HORS）与自然起源（NOR）少年相比。产卵年份和盒在河流中的位置（上游距离）是蛋盒是否从其原始位置取回的最佳预测。同时，盒子的状况（即完好，损坏或丢失）是预测青少年生产的最佳单一指标。补充卵分别代表2014、2015和2016年繁殖期Panther Creek卵总沉积的42％，50％和42％。一项亲子关系分析显示，将数据归一化到估计的卵沉积量后，卵箱分别占相应育雏年幼崽产量的6％，22％和35％，少于成卵幼崽所占的比例。被估计为自然变红。坠落时，HOR鱼的长短和扩散行为与NOR鱼不同，但从Panther Creek迁徙时，它们的长度和条件相似，并且通过联邦哥伦比亚河电力系统（FCRPS）的下游存活率无显着差异。总的来说，我们的结果为有兴趣启动或完善蛋补充计划的渔业管理者提供了有用的见识。