13th December 2010

Cornwall Wildlife Trust has completed its ‘pinger trial' this summer. The trial aims to test the practicalities and effectiveness of using ‘pingers' on fishing vessels to see how they might protect cetaceans (dolphins, porpoises and whales) from getting caught in fishermen's nets.

With the assistance of four volunteer fishermen based in Newlyn, the project has been able to collect a huge amount of information over a 12 month period, and the results are extremely encouraging.

The pinger is a device which can be fitted to fishing nets with the aim of deterring cetaceans from getting caught, acting as an acoustic deterrent. It works by emitting a regular high-pitched noise that can be heard by the cetaceans, scaring them away from the fishermen's nets and preventing accidental entanglement which usually results in death.

Tom Hardy, Marine Conservation Officer for Cornwall Wildlife Trust, says, "The project has been developed to test the practicalities of using pingers on smaller inshore fishing vessels, which will establish their viability as a conservation tool. It also aims to observe and record behavioural changes of the different species, which could be effected due to the presence of pinger."

The trial marks the beginning of an encouraging relationship between the wildlife conservation charity and some of the local fishermen, and without their co-operation with the trial the Trust would not have been able to start monitoring the effectiveness of these pingers.

Tom continues, "The fishermen working in partnership with us have been invaluable, and their experience and feedback on practical issues has been extremely helpful."

During the twelve month trial each fishing vessel was equipped with two acoustic monitoring devices (called C-PODs). These were able to record cetacean activity around nets both with and without the pingers attached, which has allowed the Trust to compare what difference a pinger can make to the animals' behaviour.

The trial initially set out to test the pingers' effectiveness on the three most common cetacean species seen in Cornish waters, which are common dolphins, bottlenose dolphins and harbour porpoises, but unfortunately there were too few dolphin interactions to statistically prove the effectiveness of pingers on them.

However, the data collected for harbour porpoises showed an amazing 48% reduction in activity recorded in the vicinity of nets with pingers.

Tom says, "This is a hugely statistically significant trend and shows how effective this type of deterrent can be. Considering the harbour porpoise is the most frequently by-caught cetacean in inshore waters, this type of deterrent could be an extremely useful management technique."

Tom continues, "This project has not only proved the effectiveness of pingers at reducing bycatch of harbour porpoises, but has also afforded the development of an extremely beneficial working partnership between commercial fishing and conservation, which we hope will lead to better protection of cetaceans in Cornwall."

Jake Freathy, a Newlyn Fishermen taking part in the trial, says, "The pingers were no problem once they were on the gear and seemed to be effective."

The Trust considers this year's pinger trial to be a great success as very few practical problems have been raised, although there are some concerns about the cost and life-span of pingers which will need to be investigated. Further work is also needed in developing pingers that are more able to cope with the rigours of being deployed in a working fishery to make them more durable.