Skip to main content
[Translate to English:]
[Translate to English:]
Institute of

OF Baltic Sea Fisheries


Porpoise Alert Projekt (PAL)

Schweinswale in der Ostsee
© Thünen-Institut/Jerome Chladek
Schweinswale in der Ostsee

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. 

Background and Objective

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:

  1. Research in the laboratory to develop the PAL signal technically and to construct a housing that is suitable to be used in commercial fisheries;
  2. Field research on harbour porpoise to optimize the avoidance strategies against gill-net dummies (without net to avoid real bycatch) that are equipped with PAL devices;
  3. Trials of PAL devices in commercial gill net fisheries in the Western Baltic sea.

Data and Methods

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 communication signal was tested in the gill net fisheries of several commercial gill net fishers in German and Danish waters 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 in the nets WITHOUT PAL than in the nets with PAL. The probability of gill nets for bycatch of harbour porpoise is reduced by 80%.

Involved external Thünen-Partners

Funding Body

  • Federal Ministry of Food und Agriculture (BMEL)
    (national, öffentlich)


12.2012 - 6.2017

More Information

Project status: finished


  1. 0

    Chladek J-C, Culik B, Kindt-Larsen L, Moesgaard Albertsen C, Dorrien C von (2020) Synthetic harbour porpoise (Phocoena phocoena) communication signals emitted by acoustic alerting device (Porpoise ALert, PAL) significantly reduce their bycatch in western Baltic gillnet fisheries. Fish Res 232:105732, DOI:10.1016/j.fishres.2020.105732

  2. 1

    Dorrien C von, Chladek J-C (2018) Sicherung der Wettbewerbsfähigkeit der deutschen Fischerei durch Entwicklung innovativer, praxistauglicher PAL-Warngeräte zur Minimierung von Schweinswal-Beifängen - Schlussbericht des Teilprojektes 1. Rostock: Thünen-Institut für Ostseefischerei, 17 p

  3. 2

    Culik B, Conrad M, Chladek J-C (2017) A new warning device. Tracks (CMS)(Ausg. COP12):82-83

  4. 3

    Culik B, Conrad M, Chladek J-C (2017) Akustischer Schutz für Meeressäuger: neues Warngerät PAL. In: Fortschritte der Akustik - DAGA 2017 : 43. Jahrestagung für Akustik, 06.-09. März 2017 in Kiel. Berlin: Deutsche Gesellschaft für Akustik eV (DEGA), pp 387-390

  5. 4

    Chladek J-C, Kindt-Larsen L, Culik B, Conrad M, Dorrien C von (2017) Listen to your PAL! Innovative alerting device significantly reduces western Baltic harbour porpoise bycatch : Poster for European Cetacean Society Conference 2017. Hamburg: Johann Heinrich von Thünen-Institut, 1 p

  6. 5

    Culik B, Dorrien C von, Conrad M (2016) Porpoise Alerting Device (PAL): Synthetic harbour porpoise (Phocoena phocoena) communication signals influence behaviour and reduce by-catch. BfN Skripten 451:150-155

  7. 6

    Culik B, Conrad M, Schaffeld T, Dorrien C von, Kindt-Larsen L (2015) Deploying Porpoise Alerting Device (PALfi) in Baltic and North Sea Gillnet Fisheries [Poster]. In: 29th Conference of the European Cetacean Society, 23rd to 25th March 2015, University of Malta, Malta . Msida: University of Malta

  8. 7

    Culik B, Dorrien C von, Müller V, Conrad M (2015) Synthetic communication signals influence wild harbour porpoise (Phocoena phocoena) behaviour. Bioacoustics 24(3):201-221, DOI:10.1080/09524622.2015.1023848

                                                                 back to Fisheries & Environment Baltic Sea

    Scroll to top