Study

Long-term effectiveness, failure rates, and ‘‘dinner bell’’ properties of acoustic pingers in a gillnet fishery

  • Published source details Carretta J.V. & Barlow J. (2011) Long-term effectiveness, failure rates, and ‘‘dinner bell’’ properties of acoustic pingers in a gillnet fishery. Marine Technology Society Journal, 45, 7-19

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 before-and-after study in 1990–2009 of multiple pelagic sites in the North Pacific Ocean, off the coasts of California and Oregon, USA (Carretta & Barlow 2011; same fishery as Barlow & Cameron 2003 and Carretta et al. 2008) found that using acoustic devices on fishing nets reduced entanglements of two of five marine mammal species, but did not reduce damage to target broadbill swordfish Xiphias gladius catches by California sea lions Zalophus californianus. The proportion of fishing net deployments with at least one entanglement was lower for nets with acoustic devices than those without for short-beaked common dolphins Delphinus delphis (with devices: 3.2%; without: 5.7%) and northern elephant seals Mirounga angustirostris (with devices: 0.5%; without: 2.4%). The difference was not significant for northern right whale dolphins Lissodelphis borealis (with devices: 0.003%; without: 0.005%), Pacific white-sided dolphins Lagenorhynchus obliquidens (with devices: 0.005%; without: 0.003%) or California sea lions (with devices: 2.6%; without: 1.6%). In one year, the proportion of deployments with swordfish catches damaged by California sea lions did not differ significantly with (19 of 69 deployments; 28%) and without acoustic devices (38 of 124 deployments; 31%). In 1990–1998, fishing nets (1,281 in total) were deployed without acoustic devices. In 1996–2009, fishing nets (2,792 in total) were deployed with acoustic devices (≥30 devices/net at 91 m intervals, emitting 300 ms pulses every 4 seconds at 10–12 kHz). Nets (each 1.5–1.8 km long, 65 m deep, 40–60 cm mesh size) were deployed for 8–20 h between dusk and dawn by a ‘drift’ gill net fishery targeting swordfish and sharks. Onboard observers recorded mammal entanglements in 1990–2009. Sea lion damage to swordfish catches (shredding of the body) was recorded in 1997.

    (Summarised by: Anna Berthinussen)

Output references

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