Abstract Understanding ecosystem drivers of fish stock performance is essential to improving conservation and management. We used a hypothesis-driven approach to identify potential ecosystem indicators and developed a retrospective analysis using regression models of steelhead trout marine survival in Puget Sound, an urban estuary in Washington State, USA, over a 30-year time series. Indicators related to predator abundance, the presence of hatchery Chinook salmon in the system, salinity of marine waters, and timing of cumulative river discharge explained the most variance in smolt survival. Seal abundance was the strongest predictor, showing a strong negative relationship with steelhead marine survival, indicating that predation pressure may influence marine survival. Several other predictors were supported in our models, but with much less individual explanatory power. Our results support the conclusion that a combination of factors with differing mechanisms have likely contributed to declining survival of steelhead in inland marine waters. This study emphasizes the importance of collecting long-term survival and environmental data, taking a hypothesis-based approach to understanding ecosystem drivers related to marine survival, and evaluating the mechanisms associated with survival for species with complex life histories like anadromous steelhead trout.

中文翻译：

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普吉特湾硬头鳟鱼海洋生存的生态系统指标

摘要 了解鱼类种群绩效的生态系统驱动因素对于改善保护和管理至关重要。我们使用假设驱动的方法来确定潜在的生态系统指标，并使用美国华盛顿州城市河口普吉特湾的钢头鳟鱼海洋生存回归模型进行了回顾性分析，该模型超过 30 年的时间序列。与捕食者丰度、系统中孵化场奇努克鲑鱼的存在、海水盐度和累积河流排放时间相关的指标解释了小鲑鱼存活率的最大差异。海豹丰度是最强的预测因子，与钢头海洋生存率呈显着负相关，表明捕食压力可能影响海洋生存率。我们的模型支持其他几个预测变量，但个人的解释力要少得多。我们的结果支持以下结论，即具有不同机制的因素的组合可能导致内陆海水中硬头鱼的存活率下降。这项研究强调了收集长期生存和环境数据的重要性，采用基于假设的方法来了解与海洋生存相关的生态系统驱动因素，并评估与溯河硬头鳟鱼等具有复杂生活史的物种的生存相关的机制。