Photos: 1,044 marine animal observations analyzed for tidal turbine collision risks

Researchers in Washington State conducted a 141-day study using a small-scale cross-flow tidal turbine equipped with optical cameras and sensors to assess collision risks between marine animals and tidal energy infrastructure. Over 109 days of optical monitoring, they recorded 1,044 observations of fish, seabirds, and seals. No collisions were observed involving seabirds or seals; seabirds appeared only when the turbine was stationary, while seals were present both day and night, including when the turbine was rotating. Four fish collisions with moving turbine blades were documented, with most fish successfully avoiding contact—over 50 fish passed without collision for every one that collided, even at flow speeds exceeding 2 m/s. This study is notable as the first in North America to use optical camera imagery to directly observe interactions between marine wildlife and tidal turbines, moving beyond theoretical risk assessments. The researchers employed two data collection methods—scheduled recording and real-time detection triggered by optical or acoustic sensors—and evaluated machine learning models to improve animal detection underwater. Challenges