Can fear conditioning repel California sea lions from fishing activities?

  • Published source details Schakner Z.A., Gotz T., Janik V.M. & Blumstein D.T. (2017) Can fear conditioning repel California sea lions from fishing activities?. Animal Conservation, 20, 425-432.


This study is summarised as evidence for the following.

Action Category

Use noise aversive conditioning to deter mammals from fishing gear

Action Link
Marine and Freshwater Mammal Conservation
  1. Use noise aversive conditioning to deter mammals from fishing gear

    A controlled study in 2013–2014 of five pelagic areas in the North Pacific Ocean, off the coast of California, USA (Schakner et al. 2017) found that attempts to condition California sea lions Zalophus californianus to avoid fishing lines by pairing a ‘startle’ sound with a ‘neutral’ sound did not reduce bait foraging behaviour. Playing ‘startle’ sounds alone reduced sea lion bait foraging behaviour by 83% and sea lions surfaced three times further from fishing vessels compared to when no sounds were played (data reported as statistical model results). However, there was no significant difference in sea lion behaviour when ‘startle’ sounds were played after a ‘neutral’ tone. Commercial passenger fishing vessels carried out fishing stops (each 0.1–2 h) across five areas with sounds played back through an underwater speaker (98 stops) or with no sounds (48 stops). Sounds were either a ‘startle’ pulse (200 ms of white noise at 10–11 kHz) or a ‘startle’ pulse played 2 seconds after a ‘neutral’ tone (6-second tone at 1–2 kHz with a 1.5 second long fade-in). Sound treatments were randomly selected during each fishing stop. Two observers on board each of the fishing vessels recorded bait foraging (sea lions taking bait from fishing lines during at least 50% of the time spent fishing) and distances of surfacing sea lions from vessels during each of the 146 fishing stops in May–September 2013 and 2014.

    (Summarised by: Anna Berthinussen)

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