Quantifiable measurement of habitat restoration effects on salmonid reproductive performance is limited, although it is necessary for evaluating whether population responses follow management actions. We investigated using close‐kin mark‐recapture methods to partition restoration effects within standard monitoring metrics of juvenile emigrants leaving the natal reach. This approach allowed for statistical comparison of relative juvenile capture rates (recruitment) from Chinook Salmon (Oncorhynchus tshawytscha) naturally reproducing in gravel augmented (restored) and nonaugmented (unrestored) reaches of a highly managed California River. Genetic parentage techniques linked adult females that had spawned in augmented and nonaugmented spawning habitats with juvenile Chinook Salmon sampled the following spring at a trap located below the natal spawning area. Successful recruitment was documented from both augmented and nonaugmented habitats, with no statistical difference between the two habitat types. The capture rate per adult female was low (0.19–0.24 juveniles/female) compared to rates observed in other systems. Within the juvenile collections, most females in the study had 0 or 1 offspring observed; however, one female that spawned in a restored habitat had 25 offspring recovered at the trap. We modeled juvenile capture rates in relation to a range of biological and environmental variables including spawning habitat site, spawning habitat treatment (augmented and nonaugmented), annual spawner abundance, year spawned, female fork length, spawning and hatch day, and flow maximum and variance. There was an inverse relationship between annual adult abundance (escapement obtained from carcass surveys) and recruitment (juvenile recoveries at trap), suggesting habitat limitation may be creating density‐dependent effects. Additionally, female body size was positively associated with recruitment, while spawning day and mean daily temperature were inversely associated with recruitment, suggesting that both biological and environmental factors independent of habitat influenced reproduction potential. This study provides evidence that habitat restoration could have an additive (incremental) positive effect on recruitment rate, informing hatchery management and restoration activities related to population recovery.

中文翻译：

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应用亲子鉴定方法检测砾石增强对幼年奇努克鲑鱼招募率的影响

栖息地恢复对鲑鱼繁殖性能影响的量化测量是有限的，尽管有必要评估种群反应是否遵循管理行动。我们研究了使用近亲标记重新捕获方法，在离开出生地的青少年移民的标准监测指标内划分恢复效果。这种方法可以对奇努克鲑鱼的相对幼鱼捕获率（招募）进行统计比较（斑鳟）在高度管理的加州河的砾石增强（恢复）和非增强（未恢复）河段中自然繁殖。遗传亲子技术将在增强和非增强产卵栖息地产卵的成年雌性与第二年春天在位于产卵区下方的陷阱中取样的幼年奇努克鲑鱼联系起来。增强和非增强栖息地均记录了成功的招募，两种栖息地类型之间没有统计差异。与其他系统中观察到的捕获率相比，每只成年雌性的捕获率较低（0.19-0.24 只青少年/雌性）。在幼年种群中，研究中的大多数雌性观察到 0 或 1 个后代；然而，一只在恢复的栖息地产卵的雌性在陷阱中发现了 25 个后代。我们对与一系列生物和环境变量相关的幼鱼捕获率进行了建模，包括产卵栖息地地点、产卵栖息地处理（增强和非增强）、年度产卵鱼丰度、产卵年份、雌叉长度、产卵和孵化日以及流量最大值和方差。每年的成虫丰度（从尸体调查中获得的逃逸量）与补充量（诱捕器中的幼虫恢复量）之间存在反比关系，这表明栖息地限制可能会产生密度依赖性效应。此外，雌性体型与补充呈正相关，而产卵日和每日平均温度与补充呈负相关，这表明独立于栖息地的生物和环境因素都会影响繁殖潜力。这项研究提供的证据表明，栖息地恢复可能对补充率产生附加（增量）积极影响，为孵化场管理和与种群恢复相关的恢复活动提供信息。