Porpoises, by-catch and the ‘pinger’ conundrum

The UK is committed to reducing or eliminating the by-catch of protected species in fisheries. Of key concern is the by-catch of harbour porpoise in static nets. Fishers do not want to catch harbour porpoise, and the only proven effective mitigation measure currently available is an acoustic device known as a ‘pinger’.
Legislative requirements for the mandatory use of pingers on larger vessels (i.e. those greater than 12 m in length) has resulted in a by-catch reduction of approximately 17% for the UK fleet annually. In most areas where the risk of by-catch is high (i.e. the southern North Sea, English Channel, and Bristol Channel), smaller inshore vessels (i.e. less than 12 m in length) account for over 90% of the fishing effort (determined as days at sea).
Small inshore vessels are not permitted to use pingers without a licence. The information required for a licence, however, makes it extremely difficult for fishers to obtain one. Without access to effective mitigation in most of the static net fleet, it seems unlikely that the UK will meet its ambition to minimize or eliminate harbour porpoise by-catch.
Finding workable and effective solutions for smaller vessels is essential. As harbour porpoise by-catch is such a rare event, it is unlikely that the mandatory use of pingers on all static net vessels will be cost-effective. Nor is such widespread deployment considered desirable because of the potential consequences on the conservation status of harbour porpoise. A potential solution within the current UK legislative framework is proposed that would facilitate the use of pingers in small-scale localized fisheries with a high risk of by-catch until a suitable mitigation alternative to pingers becomes available.