As the climate changes, warmer water temperatures may stress populations of native coldwater fishes. Simultaneously, nonnative warmwater predators may expand their ranges and interact with already at‐risk native fish populations. To explore the independent and combined effects of these two stressors on threatened salmon, we present a case study of simulated Chinook salmon Oncorhynchus tshawytscha and largemouth bass Micropterus salmoides interacting under two thermal regimes in the Snoqualmie River, Washington, USA. We applied an individual‐based and spatially explicit model that tracks fish movement and growth. We evaluated changes in Chinook salmon emergence date, outmigration date, mass, and survival. We ran simulations for four scenarios: (1) Baseline, run without either stressor, (2) Warm, run with warmer temperatures, (3) Predator, run with largemouth bass, and (4) Warm‐Predator, run with both stressors. We assessed outcome metrics relative to the Baseline scenario. In the Warm scenario, salmon emerged 37 d and outmigrated 55 d earlier. There were 61% more subyearling migrants that were 31% smaller, and 72% fewer yearlings. In the Predator scenario, salmon survival decreased 64% for subyearlings and 69% for yearlings, and subyearlings were 7% smaller. In the Warm‐Predator scenario, salmon emerged 39 d and outmigrated 59 d earlier, subyearling survival increased 22%, subyearling mass decreased 37%, and 93% fewer yearlings survived. Our results suggest that warmer temperatures shift emergence and outmigration; predation by nonnative species is a threat to salmon survival; and life history strategies experience these stressors in different ways. Whereas subyearling production benefited from warmer temperatures more than it was hurt by predation, yearling production was depressed by both stressors independently and combined. Managers can use our individual‐based and spatially explicit approach to identify key times and areas to address exposure to extreme temperatures, overlap with nonnative species, and their interactive effects on threatened salmon. Our case study addressed three pressing needs identified in the literature: investigate impacts of nonnative species on threatened native salmon, build tools to evaluate management options where bass and salmon overlap, and explore how freshwater fishes will contend with multiple interactive stressors.

中文翻译：

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基于个体的模拟表明温度升高和外来捕食者对奇努克鲑鱼的混合影响

随着气候变化，水温升高可能会给本地冷水鱼类带来压力。同时，外来温水捕食者可能扩大范围，并与已经处于危险中的本地鱼类种群互动。为了探索这两种应激源对受威胁鲑鱼的独立和综合影响，我们以模拟的奇努克鲑鱼Oncorhynchus tshawytscha和大嘴鲈Micropterus salmoides为例进行研究。在美国华盛顿州斯诺夸尔米河的两个热力条件下相互作用。我们应用了基于个体的空间显式模型来跟踪鱼类的运动和生长。我们评估了奇努克鲑鱼出苗日期，迁出日期，数量和存活率的变化。我们针对四种情况进行了仿真：（1）基线，不使用任何压力源运行；（2）温暖，在较高温度下运行；（3）捕食者，使用大嘴鲈鱼运行；（4）温暖-捕食者，使用两个压力源运行。我们评估了相对于基准情景的结果指标。在温暖的情况下，鲑鱼出现了37 d，而移出了55 d。一岁以下移民增加61％，一岁以下移民减少31％，一岁以下移民减少72％。在“捕食者”情景中，一岁鲑的鲑鱼存活率降低了64％，一岁鲑的存活率降低了69％，而一岁鲑的存活率则降低了7％。在“暖食掠食者”情景中，鲑鱼出现39 d，更早移出59 d，亚一岁成活率提高了22％，亚一成体质量下降了37％，一岁成年体减少了93％。我们的结果表明，温度升高会改变出苗和迁出的现象。外来物种的捕食对鲑鱼的生存构成威胁；生活史策略会以不同方式体验这些压力源。次季生产受益于温暖的温度而不是被掠食所损害，而一岁生产受到两个压力源的独立和联合压制。管理者可以使用基于个人的，空间明确的方法来确定关键时间和区域，以应对极端温度，与外来物种重叠以及对受威胁鲑鱼的互动影响。