Diel timing of lake sturgeon (Acipenser fulvescens) activity revealed by satellite tags in the Laurentian Great Lake Basin

Lake sturgeon (Acipenser fulvescens) are slow-growing and long-lived residents of the Laurentian Great Lakes Basin, making them vulnerable to anthropogenic stressors. The behavior of lake sturgeon, and how it may result in conflict with human activities, remain incompletely understood. Our goal was to describe how environmental conditions, such as depth, temperature, and time of day, influence lake sturgeon activity. Data were recorded using pop-up archival satellite tags, which have provided insight into the ecology, physiology, and behavior of challenging to study marine megafauna, yet are rarely deployed within freshwater ecosystems despite parallel research needs. Adult lake sturgeon were fitted with satellite tags containing integrated accelerometers near spawning grounds in the Niagara River between Canada and the United States. We used the time-series of acceleration in recovered tags to test the hypothesis that lake sturgeon exhibit diel activity cycles in situ. We defined activity as acceleration greater than two standard deviations from a running average. We applied this classification to partial records obtained from satellite transmission, an approach that can render incomplete datasets a useable product for analysis. Lake sturgeon were most active nocturnally with a significant mean at 22:32 h. Generalized linear mixed-effect models showed temperature and time of day to be significant predictors of activity. Temporal cycles of fish activity should be understood and could be exploited to reduce human-fish conflict in the increasingly altered waterways of the globe.