Securing the competitiveness of the German fishery by the development of innovative, suitable PAL warning devices to minimize the bycatch of harour porpoises
Harbour porpoises get entangled and drown in gillnets which they are not able to detect by their acoustic sense of direction. The Thünen Institute was partner in an innovation project, that developed and tested devices that shall protect harbour porpoises against bycatch.
Protecting harbour porpoises against bycatch shall be achieved by technical measures which use most recent knowledge about the behavior of these small cetaceans regarding communication and orientation. A suitable technical innovation, to be used by the German gillnet fishery, was developed and tested that reduces the conflict between economical and nature conservational targets and thus gives the German fisheries sector a sustainable competitive perspective.
The Project was organised in three steps:
TI-OF organised mainly the field trials of the PAL devices in the commercial gill net fisheries and analyses the results. Thus, practicability and effectiveness of PALs was tested, but also, whether these devices might potentially have an impact on amount and composition of catches of target fish species.
Main result of this project: A new, innovative alarming device is able to significantly reduce the bycatch of harbour porpoise in gill net fisheries. In addition, better data about fishing effort and patterns as well as bycatch rates in the gill net fisheries were achieved by carrying out the commercial fisheries trials.
A suitable harbour porpoise communication signal, which in field experiments lead to avoidance reactions and increased the click-rate of wild harbour porpoises, was identified. The experimental results were reported in a scientific research paper (Link) and in a poster at the yearly European Cetacean Society conference in Malta 2015. The communication signal was tested in the gill net fisheries of several commercial gill net fishers until the end of 2016. The fishers set half of their nets equipped with PALs, the other half of their nets without PALs as control. The results in the Western Baltic are unequivocal: Significantly more harbour porpoises were bycaught und in the nets WITHOUT PAL than in the nets with PAL. The probability of gill nets for bycatch of harbour porpoise is reduced by 70%.
Currently the PAL project is in the final analysis and reporting phase. Several scientific publications are being drafted as well as presentation for stakeholder meetings and scientific conferences are being prepared.
12.2012 - 6.2017
Project status: finished