Welsh tidal turbines could be catastrophic for porpoises

We’ve been studying how Risso’s dolphins and harbour porpoises use the waters around Ynys Enlli since 1999. Our research demonstrates that this special place is an important nursing ground for harbour porpoises and Risso’s dolphins and the unique tidal flows in Bardsey Sound (Swnt Enlli) are a prime feeding area. Our research was fundamental in supporting the designation of the West Wales Marine SAC.

The wave and tidal energy industry is still new, and the devices used to generate electricity still very much untested for their impacts on the marine environment and whales and dolphins. As a result, there is no data on which a reliable assessment of the impacts can be made.

What little evidence exists demonstrates a real cause for concern, in particular:

1. Collision risk - the prospect of dolphins or porpoises swimming into the underwater devices, is extremely worrying, as the moving blades can injure or even kill them. The few studies on this have clearly demonstrated that this is a high risk in areas where harbour porpoises live.
2. Changes to tidal flow - studies show how tidal turbines change the local tidal flow in the area around them, and the more turbines there are, the larger the area that’s affected. These changes are likely to cause changes in the movement of prey species. Harbour porpoises need to feed almost continuously to meet their energy needs and so disturbance to the fish that they eat is a massive problem for them. This could force them from their feeding grounds entirely.
3. Noise disturbance - Noise pollution during construction of other offshore renewables developments caused harbour porpoise populations to leave the area during construction and, in many cases, not returning in their usual numbers. Tidal power infrastructure will also require construction and maintenance, resulting in increased boat traffic which could disrupt marine wildlife and increase the risk of boat collisions.