Aarhus University Seal / Aarhus Universitets segl


Back in 1994, a investigation of fishing boats in the North Sea found that around 7000 harbour porpoises drowned in Danish gill nets. This result kickstarted a huge public debate and a claim for political action was raised.

But despite multiple science research projekts and several new laws tending to reduce bycatch of porpoises, in gill net fisheries, in Europe and USA, no overall solution have been accepted. This might be due to the fact that we still have limited knowledge about porpoises ability to registre the nets by using sound and echolocation, and there behavior near the nets. The Danish Nature agency made regulations for reducing bycatch of porpoises in 1998 and in January 2005 a new EU law was made to make Fishing boats longer than 12 use pingers in most of their gillnets. In the last couple of years, specialized gill nets have been used to register the porpoise echolocalization, and gill nets have been made more difficult for the porpoises to get entangled. The research and monitoring is a continuing project with the goal of optimize the initiatives to reduce bycatch

Gill Nets

 A Gill net is a net that is placed vertical in the water column, like a "fence". It is connected to the bottom or flowding freely in the water between two poles. They are often used to catch cot and flatfish. 


A pinger is an acoustic alarm with the purpose of making the porpoise aware of the nets, and then hopefully reduce the risk of bycatch.

Further information

Porpoise surveillance report in pingerfisheries from DCE

 Fuld report