Acoustic devices keep dolphins and porpoises at bay.

Porpoise caught in gill nets around 1992.

Encouraging results from trials involving four vessels in the Cornwall are being analysed at the moment according to Marine Conservation Officer Tom Hardy from the Cornwall Wildlife Trust who spoke on Radio Cornwall's Breakfast Show this morning.  The vessels were fitted with acoustic pingers with a range of about 400m that have helped prevent the nets from catching cetaceans as in the image above. Hydrophones were placed on the nets by the trial teams and used to ascertain the extent of cetacean presence in the areas being fished. The trials targetted vessels under 10m which at present have no requirement to work with pingers.

More details here.