2009-10-15 11:11

Pingers in Puck bay will protect porpoises

A chain of electronic warning devices - pingers - that have been put in to the waters of the Puck bay, are to scare away porpoises and prevent them from getting tangled up in fishing nets. The project was presented at the VII Baltic Science Festival organized in the Tri-City.

Porpoises, are small cetaceas (they reach up to 170 cm.) related to dolphins. They are a protected species in the Baltic sea, since only a few hundred of them live there. Due to the fact that they mainly live on small fish, they often get tangled up in fishing nets - which is called a by-catch. They are mammals, so when they can't surface they die, due to lack of oxygen. Porpoises use ultra sounds to find their way under water do not notice thin nylon nets. For them the nets are invisible traps.

To prevent this, an initiative that came out of the University of Gdańk's Sea Station in Puck Bay started a system of detectors and devices to keep porpoises away from fishing areas. Those devices are called pingers.

Pingers work in a similar way to hooters - every few seconds they emit sounds, that scare away porpoises, but are not audible for fish. Depending on the model, and batteries, the pingers can work between 1 to 2 years. They only turn on, when they are under water.

In many countries they are put on to fishing nets, but this is very expensive. The pinger line in Puck bay is the solution, and it is also a lot cheaper. This means that fishermen do not have to spend their own money on extra devices, that discover and scare away porpoises. Thanks to placing extra devices that discover this specie it will be possible to see how effective are the pingers.

PAP - Science and Scholarship in Poland, Paweł Wernicki, tr. ajb

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