Fish migration in rivers is a growing area of concern as mounting anthropogenic influences, particularly fragmentation from dams and barriers, constitute major threats to global river species diversity. Barriers can impede the movement of fishes between areas critical to the completion of their lifecycle, affecting both population and ecosystem viability. In response, fish passage solutions have been identified as a critical need to maintain fisheries viability in the Laurentian Great Lakes, and around the world. Pivotal to the success of these fish passage solutions is a more complete understanding of the movement phenology and environmental cues that instigate migration. We used a dual-frequency identification sonar (DIDSON) to evaluate environmental triggers of river entry during spring and summer for three size classes of migratory fishes in the Boardman River, a Lake Michigan tributary. Our results indicate that medium size fish (>30 cm and < 50 cm), primarily composed of white sucker Catostomus commersonii and longnose sucker Catostomus catostomus were 21% more likely to enter the river at sunset and 25% less likely at midnight in comparison to midday. Entry rates of medium fish increased 6% for every 1 °C increase in river temperature, 4% for every 1 m³/s increase in river discharge from the day prior, and were reduced by 1% for every 10 cm increase in lake level. Understanding these processes in the tributaries of the Great Lakes is important to inform the fish passage solutions currently being developed for the Boardman River, and to inform management regulations for Great Lakes migratory fishes.

河流中的鱼类洄游是一个日益受到关注的领域，因为越来越多的人为影响，特别是大坝和障碍的碎片化，对全球河流物种多样性构成了重大威胁。障碍会阻碍鱼类在对其生命周期完成至关重要的区域之间移动，从而影响种群和生态系统的生存能力。作为回应，鱼类通过解决方案已被确定为维持劳伦森五大湖和世界各地渔业生存能力的关键需求。这些鱼类通过解决方案成功的关键是更全面地了解促使迁移的运动物候和环境线索。我们使用双频识别声纳 (DIDSON) 来评估密歇根湖支流博德曼河中三个大小级别的洄游鱼类在春季和夏季进入河流的环境触发因素。我们的结果表明，中型鱼（> 30 厘米和 < 50 厘米），主要由白色吸盘组成与中午相比，Catostomus commersonii和长鼻吸盘Catostomus catostomus在日落时进入河流的可能性要高 21%，在午夜进入河流的可能性要低 25%。河流温度每升高 1°C，中型鱼类的进入率增加 6% ，河流流量比前一天每增加1 m ³ /s 增加4% ，湖水位每增加 10 cm 减少 1% . 了解五大湖支流中的这些过程对于为目前正在为博德曼河开发的鱼类通过解决方案提供信息以及为五大湖洄游鱼类的管理规定提供信息非常重要。