Study

Experimental testing of acoustic alarms (pingers) to reduce bycatch of harbour porpoise, Phocoena phocoena, in the state of Washington

  • Published source details Gearin P.J., Goso M.E., Laake J.L., Cooke L. & DeloNo R.L. (2000) Experimental testing of acoustic alarms (pingers) to reduce bycatch of harbour porpoise, Phocoena phocoena, in the state of Washington. Journal of Cetacean Research and Management, 2, 1-9

Actions

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 1995–1997 of a pelagic area in the North Pacific Ocean, off the coast of Washington, USA (Gearin et al. 2000) found that fishing nets with acoustic devices attached had fewer entanglements of harbour porpoises Phocoena phocoena than nets without acoustic devices, but the number of harbour seal Phoca vitulina entanglements did not differ. In 1995 and 1996, harbour porpoise entanglement rates were lower in fishing nets with acoustic devices attached (0.02 porpoises/net/day) than without (0.4–0.5 porpoises/net/day). Harbour seal entanglement rates did not differ with or without acoustic devices (both 0.05 seals/net/day). In 1997, with acoustic devices on all nets, entanglement rates were 0.07 porpoises/net/day and 0.07 seals/net/day. Catches of target chinook salmon Oncorhynchus tshawytscha and sturgeon Acipenser spp. did not differ significantly with or without acoustic devices (see original paper for data). In 1995 and 1996, two pairs of gill nets (183 m long, 50–80 meshes deep) were deployed on the ocean bottom at depths of 8–12 m, spaced >300 m apart. One net in each pair had 11 acoustic devices (‘piezo buzzers’) attached at 17 m intervals 4–7 m below the surface; the other had no devices. The devices (emitting pulses every 4 seconds with peak frequencies at 3 and 20 kHz) were rotated between nets. In 1997, all four nets had acoustic devices attached. Nets were checked every 24 h on 51–61 days in July–August 1995 and 1996 and 180 days in June–August 1997.

    (Summarised by: Anna Berthinussen)

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