At the end of September 2018 fishermen fishing in the sea waters of the Wolin National Park received free pingers – acoustic devices which warn porpoises of fishermen’s nets.

The pingers were purchased as part of the project entitled “The protection of marine mammals and birds and their habitats”, jointly implemented by the Prof. Krzysztof Skóra Marine Station of the University of Gdańsk’s Institute of Oceanography and WWF Poland. At present pingers are the most effective, and at the same time the easiest, method to stop porpoises from dying after becoming trapped in fishing nets, which pose one of the main threats to these animals.

What are pingers?

They are devices which, by emitting sounds of a certain frequency, are meant to warn porpoises of the danger posed by fishing nets. They are usually attached to nets, thus preventing porpoises from approaching them, becoming entangled and dying as a result of strangulation. The pingers’ pulsating tone is emitted at a range audible only by these small cetaceans, without scaring the fish or affecting the fishermen’s yield.

Similar to bats, porpoises use echolocation. They send sound waves which, by bouncing off nearby objects, provide them with the necessary information regarding distance from objects as well as their size or shape. The synthetic and very thin modern net fibres do not reflect the sounds emitted by porpoises in a way in which they might bounce back in time and with an appropriate force. If the reflected echo is too weak, porpoises become entangled in nets and die as a result of a lack of oxygen.

Using pingers is a way of meeting the needs of the inshore fishing industry while protecting an endangered species. Fishermen who use pingers help to create a positive image of their profession with the public and, while successfully carrying out their work, they also have a hand in saving great numbers of porpoises.

“Pingers are a very effective method of limiting the bycatch of the porpoise, which is critically endangered in the Baltic. We are glad that fishermen are not indifferent to the fate of these beautiful mammals and are eager to become involved. Pingers bought as part of the project are waiting for those willing to take part and are available for free at the UG’s Marine Station in Hel. They can also be delivered to fishing centres”, said Maria Jujka-Radziewicz, WWF Poland’s specialist for the protection of marine ecosystems.

The owners of fishing boats less than 12 m in length who have been issued pingers, are soon going to attach them to their nets, thus rendering their fishing “porpoise-friendly”. At the same time, this will probably be the first time that owners of fishing boats shorter than 12 m will use pingers in the Polish Sea Areas. Following Council Regulation (EC) No 812/2004, such an obligation rests only with the owners of boats longer than 12 metres fishing by means of gillnets in the 24 ICES area (western part of the Polish Sea Areas).

“Gillnets are the basic fishing tool used by fishing vessels, mostly boats less than 12 metres long, which constitute 80% of the Polish fishing fleet. This makes them the most commonly used fishing tools in the Polish Sea Areas. For this reason, Regulation No 812/2004 which requires the use of pingers, does not work in the Polish Sea Areas for two basic reasons – firstly, it concerns only larger vessels, which are outnumbered by fishing boats and which less often employ nets which require pingers, and secondly, it limits their use to a small area of the Polish Baltic waters i.e. 24 ICES (western part of the Polish Sea Areas)”, said Wojciech Górski from the Prof. Krzysztof Skóra Marine Station of the University of Gdańsk in Hel.

In order to fill this gap in the law, the pingers purchased as part of the project “The protection of marine mammals and birds and their habitats” will be available free of charge to owners of vessels less than 12 metres in length.