Climate warming and high salmon migration mortality

太平洋鲑鱼支持加拿大西部最有价值的商业和休闲渔业，每年产生超过10亿美元的收入。它们是食物链的重要组成部分，是太平洋海岸第一民族神话、精神完整性和当地经济不可或缺的组成部分，是普通公众的标志，丰富的三文鱼证实了健康和原始的环境。大多数太平洋鲑鱼种群在向上游产卵的过程中遇到了比有记录以来任何时候都更温暖的河流。弗雷泽河是加拿大产量最高的鲑鱼系统，在过去10年里经历了有记录以来最热的8次夏季水温，气候模型预测在不久的将来气温会更高。与这些高温相关的是高水平的迁徙死亡率，大大降低了渔业成本，数百万条鱼种在迁徙过程中消失或死亡，没有产卵。这种现象构成了严重的保护风险，并使弗雷泽红眼的可持续性受到质疑。新的政策已经将红鲑鱼的捕捞从寒冷的海洋转移到温暖的河流地区，这使得三文鱼如果逃脱或从捕获中释放出来，将处于双重危险中，因为在高温下挣扎可能会导致释放后几个小时的死亡。我们将进行实验，以建立可以预测预期热暴露以及与不同水平的非滞留河里捕鱼相互作用的死亡率的标准，并评估成年迁徙热暴露对卵和后代的影响。我们的发现将提供重要的信息，用于帮助渔业管理机构--我们在该项目中的合作伙伴--完成预测迁徙死亡率、预测未来种群大小和管理栖息地以保护资源的任务。

Pacific salmon support the most valuable commercial and recreational fisheries in western Canada generating over $1 billion of revenue annually. They are an important component of the food chain, are integral to mythology, spiritual integrity, and local economies of Pacific coast First Nations, and are icons for the general public, with abundant salmon confirming healthy and pristine environments. Most stocks of Pacific salmon now encounter warmer rivers during their up-river spawning migration than in any time since records were kept. The Fraser River is Canada's most productive salmon system and has experienced in the past 10 years eight of the hottest summer water temperatures on record, and climate models predict even warmer temperatures in the near future. Associated with these high temperatures have been high levels of migration mortality costing the fishery significantly with millions offish disappearing during migrations or dying unspawned. This phenomenon constitutes a severe conservation risk and puts the sustainability of Fraser sockeye in doubt. New policies have shifted sockeye salmon harvesting from cool ocean to warm river locations which puts salmon in double jeopardy if they escape or are released from capture because struggling under high temperatures can lead to mortality hours after release. We will conduct experiments to establish criteria which can predict mortality rates from expected thermal exposure and interactions with different levels of non-retention in-river fishing, and to assess effects of adult migratory thermal exposure on eggs and offspring. Our findings will provide important information that will be used to help the fisheries management agencies, our partners in this project, with their task of predicting migration mortality, predicting future stock sizes, and managing habitat to conserve the resource.