A trial of a device to stop dolphins and porpoises getting caught in fishing nets has been a success, according to the Cornwall Wildlife Trust.

The one year project has seen a 48 % reduction in harbour porpoise activity around nets attached with "pingers". These devices are placed on nets and let out a noise to repel dolphins, porpoises and similar creatures.

Four Cornish boats were involved in the trial. Acoustic devices on the nets recorded the numbers of animals that approached the nets.

The results, which have been published in the Journal of Cetacean Research and Management. Ruth Williams from the trust said: "We are delighted that the trials proved such a success, not only in testing what could be an essential tool in protecting our enigmatic and precious inshore dolphins and porpoises, but also in building good relationships with the fishing industry in this county.

"The feedback from the skippers involved and the trust's investigation have concluded that there are no significant practical problems using pingers on the fishing vessels.

"The initial cost - about £50 - and short battery life of the pingers are an issue, but the trust is dedicated to continuing this research to find a suitable commercial pinger that can be used effectively on all inshore fishing boats."