This report summarizes the risks of injurious collision that marine renewable devices may pose to marine mammals, fish and birds using Scottish waters within the SEA assessment area. A collision is considered to be a physical contact between a device or its pressure field and an organism, that may result in an injury (however slight) to that organism. We did not consider the physical impacts of sound. Vertebrates may avoid collisions by moving away from the immediate area around a device (avoidance) or by escaping at close range (evasion, analogous to swerving to prevent collision with an obstacle in the road).
Other than barrages, neither wave nor tidal renewable devices have reached commercial scale deployment off Scotland. Consequently the precedent to evaluate vertebrate collision risks is severely limited. We therefore reviewed the known impacts of other industrial and natural activities with physical parallels. We considered shipping, fisheries, power station cooling intakes, fish aggregation devices, wind turbines and killer whale predation.