Determining optimal pinger spacing for harbour porpoise bycatch mitigation

  • Published source details Larsen F., Krog C. & Eigaard O.R. (2013) Determining optimal pinger spacing for harbour porpoise bycatch mitigation. Endangered Species Research, 20, 147-152.


This study is summarised as evidence for the following.

Action Category

Use acoustic devices on fishing gear

Action Link
Marine and Freshwater Mammal Conservation
  1. Use acoustic devices on fishing gear

    A controlled study in 2006 of multiple pelagic sites in the North Sea, Denmark (Larsen et al. 2013) found that fishing nets with acoustic devices attached at two different spacings had fewer entanglements of harbour porpoises Phocoena phocoena than nets without acoustic devices. Overall, entangled porpoises were recorded in fewer hauls of fishing nets with acoustic devices attached at 455 m spacings (0 hauls) and 585 m spacings (5 hauls) than nets with no acoustic devices attached (22 hauls). Numbers of entanglements did not differ significantly between the two device spacings. Average catch rates of target hake Merluccius spp. did not differ significantly between nets with acoustic devices at 455 m spacings (29 fish/km/day) and nets without acoustic devices (30 fish/km/day; data not reported for nets with devices at 585 m spacings). Strings of 45–135 gill nets were deployed during five commercial fishing trips in July–September 2006. The nets had acoustic devices (Aquatec AQUAmark 100) attached at spacings of 455 m (24 hauls) or 585 m (43 hauls) or had no devices attached (41 hauls). Observers on board the fishing vessels recorded porpoise entanglements and hake catches within each of the 108 hauls.

    (Summarised by: Anna Berthinussen)

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