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Acoustic deterrence using startle sounds: long term effectiveness and effects on odontocetes

Acoustic deterrence using startle sounds: long term effectiveness and effects on odontocetes

Monday, November 25, 2013

ISBN: 9781784120801

This report presents the findings of field experiments aimed as testing the long-term effectiveness of a new deterrence method (acoustic startle reflex)on pinnipeds.

Executive Summary

Pinniped predation on fish farms is a worldwide problem and can result in significant losses to the industry. A wide range of seal control measures are employed at fish farms to minimise the impact of seal predation, including Acoustic Deterrent Devices (ADDs). Commercially available ADDs can cause stress, hearing damage and deter non-target species such as dolphins and porpoises from their natural habitat.

A previous study using very short noise bursts to startle seals has shown that alternative methods may be available to deter seals. In this project, a startle ADD prototype was tested for 13 months at a salmon farm, and also for short periods of time at two other farms with acute seal predation problems caused by seals. During the 13 months test phase at the salmon farm only five minor predation events were noted. Seals, porpoises and otters still approached the farm during the 13 months, but no additional predation was observed. Short term tests at two fish farms with high predation, reduced predation to zero within one day of ADD deployment.

The study showed that the startle ADD is successful at preventing seal predation over 13 months and does not affect the distribution of harbour porpoises in the area.