Refining estimates of collision risk for harbour seals and tidal turbines

Scottish Marine and Freshwater Science Vol 7 No 17

There is currently considerable uncertainty regarding the potential for lethal and injurious interactions between marine mammals and tidal turbines. This uncertainty is particularly concerning for harbour seals in the Orkney and North Coast management unit, where the population has been undergoing a protracted decline. This has led to constraints being placed on tidal developments in this area until more information is available on the real risks presented to this species by tidal turbines. The aim of this research project was to provide improved assessments of the level of mortality to harbour seals potentially caused by tidal turbines in the Pentland Firth and Orkney Waters region, using recently available information from a number of areas of work. These include the consequences of collision for individuals, detailed information on tidal flow, updated tidal turbine parameters and data on temporal and spatial variation of harbour seals within the water column. Specifically, this project was developed to review the assessment process to determine areas where inputs could be refined to improve estimates in the short term; and to use the outputs of these reviews to generate an updated model that is fit for use to estimate the no-avoidance collision rates between seals and tidal turbines. Finally, this updated model was applied to an agreed envelope of consented tidal energy projects in the Orkney and Pentland Firth region. This envelope consisted of two projects: the MeyGen Phase 1a array of four turbines at the Inner Sound in the Pentland Firth, and the multiberth European Marine Energy Centre (EMEC) tidal test site at the Fall of Warness, Orkney.