Burford Benjamin P, Notch Jeremy J, Poytress William R, Michel Cyril J
Institute of Marine Sciences' Fisheries Collaborative Program, University of California, Santa Cruz, Santa Cruz, California, USA.
Fisheries Ecology Division, Southwest Fisheries Science Center, National Marine Fisheries Service, National Oceanic and Atmospheric Administration, Santa Cruz, California, USA.
Ecol Appl. 2025 Jul;35(5):e70070. doi: 10.1002/eap.70070.
Anthropogenic habitat change frequently outpaces the adaptive capacity of migratory taxa, placing many species and populations at risk of extirpation or extinction due to the mismatch of natural migration phenology and suitable conditions. While dynamic protection can greatly benefit migratory species, it is contingent on the flexibility of relevant management actions. For regulated ecosystems where advanced management planning is required, we present a new framework-facilitated migration-for actively matching natural migration phenology with suitable conditions for successful migrant passage. Using a case study of juvenile Chinook salmon (Oncorhynchus tshawytscha) oceanward migration in the Sacramento River, a major bottleneck to the recovery of imperiled populations in California, we show how the conditions associated with migration preparation, migration initiation, and successful migrant passage could be regulated to benefit migrants. Thermally shifted preparation, flow pulse-mediated initiation, and passage protection via increased flow, all accomplished by controlling the release of water from storage reservoirs, could increase the number of natural-origin Chinook salmon populations successfully migrating to the ocean by 43%-479% compared to the status quo management scenario. To further inform expected outcomes, we find that the temporal scope and diversity of juvenile salmon lifestages studied via acoustic telemetry should be expanded, and that the range of flows and flow changes that juvenile salmon experience should be increased. Facilitated migration works by synchronizing migration-thus, a prudent course of action when implementing this strategy would be to favor event quality over event quantity. In forcing scientists and managers to critically evaluate how migrations can be supported and manipulated, facilitated migration will help migratory species persist in anthropogenically altered ecosystems.
人为栖息地变化的速度常常超过迁徙类群的适应能力，由于自然迁徙物候与适宜条件不匹配，许多物种和种群面临灭绝或绝迹的风险。虽然动态保护能极大地惠及迁徙物种，但这取决于相关管理行动的灵活性。对于需要提前进行管理规划的受调控生态系统，我们提出了一个新框架——促进迁徙，以主动使自然迁徙物候与适宜条件相匹配，从而实现迁徙者的成功通行。以加利福尼亚州萨克拉门托河中奇努克鲑幼鱼向海洋洄游为例，这是该州濒危种群恢复的一个主要瓶颈，我们展示了如何通过调控与迁徙准备、迁徙启动以及迁徙者成功通行相关的条件来造福迁徙者。通过控制水库放水实现的温度转移准备、流量脉冲介导的启动以及通过增加流量实现的通行保护，与现状管理方案相比，可使自然来源的奇努克鲑成功洄游至海洋的种群数量增加43% - 479%。为进一步了解预期结果，我们发现应扩大通过声学遥测研究的幼鲑生命阶段的时间范围和多样性，并且应增加幼鲑所经历的流量范围和流量变化。促进迁徙通过使迁徙同步来发挥作用，因此，实施该策略时谨慎的做法是注重事件质量而非数量。通过促使科学家和管理者严格评估如何支持和操控迁徙，促进迁徙将有助于迁徙物种在人为改变的生态系统中持续生存。
