There is a concern that submerged tidal energy devices placed within a tidal current will present an obstacle to wildlife within the tidal channel and there is a risk of collision as a result. Although concerns are primarily for cetaceans and pinnipeds there is also some concern of the risk to fish, particularly Atlantic salmon (Salmo salar). Due to the risks posed, Marine Scotland has recommended that an assessment of collision risk to fish is informed by project specific collision risk modelling (CRM).
CRM is used to assess this risk for Atlantic salmon and it uses a physical model of a rotor and the body size and swimming activity of Atlantic salmon to estimate the potential collision rate. It focuses on the number of animal transits through a rotating rotor and the collision risk during each transit. Following the calculation of the collision risk, likely avoidance behaviours can be applied and a realistic collision rate can be determined (Band, 2015).
This technical note discusses the collision risks associated with various scenarios at the Brims Tidal Array, located in the Pentland Firth to the south of the island of Hoy, Orkney.