1. Habitat enhancements seek to ameliorate the detrimental effects of environmental degradation and take many forms, but usually entail structural (e.g. logs, cribs, reefs) or biogenic (e.g. carrion additions, vegetation plantings, fish stocking) augmentations with the intent of increasing fish annual production (i.e. accrual of new fish biomass through time). Whether efforts increase fish production or simply attract fish has long been subject to debate.
2. Streams of the Pacific Northwest are commonly targeted for habitat enhancements to mitigate for the detrimental effects of dams and other forms of habitat degradation on Pacific salmon. Nutrient mitigation (i.e. the practice of artificially fertilising freshwaters) is a form of biogenic habitat enhancement that attempts to mimic the enrichment effects of a natural Pacific salmon spawning event. This approach assumes nutrient augmentations alleviate nutrient limitation of primary producers and/or food limitation of primary and secondary consumers, culminating in increased fish production.
3. We conducted a multi‐year manipulative experiment and tracked responses of interior rainbow trout (Oncorhynchus mykiss) to annual additions of Pacific salmon carcasses as part of an effort to enhance the productivity of salmonid populations in streams where salmon runs have been lost. We employed an integrated approach to partition the mechanisms driving numerical responses of trout populations across timescales, to assess population turnover, and to track responses to habitat enhancements across individual to population level metrics.
4. Short‐term numerical increases by trout were shaped by immigration and subsequently via retention of individuals within treatment reaches. As trout moved into treated stream reaches, individuals foraged, grew, and subsequently moved to other locations such that short‐term increases in fish numbers did not persist from year to year. All told, additions of salmon carcasses alleviated apparent food limitation and thereby increased secondary production of rainbow trout. However, at an annual time scale, increased production manifested as larger individual fish, not more fish within treated reaches. Fish movements and high population turnover within treated stream reaches apparently led to the subsequent dispersal of increased fish production.
5. We found multiple lines of evidence that indicated that annual additions of salmon carcasses aggregated rainbow trout and enhanced their annual production. Through this replicated management experiment, we documented dynamic individual and population level responses to a form of stream habitat manipulation across weekly and annual timescales.

中文翻译：

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多条证据显示，复杂的虹鳟鱼对河流栖息地增强的反应

1. 栖息地的改善旨在减轻环境退化的不利影响，并采取多种形式，但通常需要增加结构性（例如，原木，婴儿床，礁石）或生物性（例如添加腐肉，种植植物，养鱼），以增加鱼类的年产量（即随着时间的推移增加新的鱼类生物量）。努力增加鱼类产量还是仅仅吸引鱼类一直是争论的焦点。
2. 西北太平洋的溪流通常以增强栖息地为目标，以减轻大坝和其他形式的栖息地退化对太平洋鲑鱼的不利影响。营养缓解（即人工施肥淡水的做法）是一种生物栖息地增强的形式，试图模仿天然太平洋鲑鱼产卵事件的富集作用。这种方法假设营养增加会减轻初级生产者的营养限制和/或初级和次级消费者的食物限制，最终导致鱼类产量增加。
3. 我们进行了一个多年的操纵性实验，跟踪了内部虹鳟（Oncorhynchus mykiss）对每年增加太平洋鲑鱼ses体的反应，以努力提高失去鲑鱼养殖流的鲑鱼种群的生产力。我们采用了一种综合方法来划分跨时间尺度驱动鳟鱼种群数字响应的机制，评估种群周转率，并跟踪从个体到种群水平指标对生境增强的响应。
4. 鳟鱼的短期数值增加是由移民影响的，随后是受治疗范围内个体的保留。随着鳟鱼进入经过处理的河段，个体开始觅食，生长并随后移至其他地点，以致每年的鱼类数量不会持续短期增加。综上所述，添加鲑鱼cas体可减轻明显的食物限制，从而增加虹鳟的次级生产。但是，在每年的时间尺度上，产量的增加表现为个体鱼的数量增加，而不是经过处理的河段内的鱼数量增加。经过处理的溪流中鱼的移动和高种群周转率显然导致鱼产量增加的随后分散。
5. 我们发现了多条证据，表明每年添加的鲑鱼尸体会聚集虹鳟鱼并提高其年产量。通过该重复的管理实验，我们记录了在每周和每年的时间尺度上，对某种形式的河流栖息地操纵的动态个人和人口水平响应。