Listening in

Active sonar is being 'trained' to identify sea mammals in a bid to cut the costs of monitoring tidal turbines and speed up the development of marine energy in Britain. The sonar is just one part of the technological response to a very human - and animal - problem. Will underwater turbines harm seals, dolphins and sea birds? And how would we know if they did? The world's largest environmental marine-energy monitoring project in Northern Ireland has not found that tidal turbines are having a measurable impact on seals, dolphins and sea-birds after three years of a five-year study. But, while marine biologists say it could take a decade to be sure, developers say more expensive monitoring could cripple the fledgling tidal energy industry. Academics are hoping technology might offer a compromise.