Non‐lethal management of carnivore predation: long‐term tests with a startle reflex‐based deterrence system on a fish farm

Published source details Götz T. & Janik V.M. (2016) Non‐lethal management of carnivore predation: long‐term tests with a startle reflex‐based deterrence system on a fish farm. Animal Conservation, 19, 212-221.
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This study is summarised as evidence for the following.

	Action	Category
	Use acoustic devices at aquaculture systems Action Link
	Use acoustic devices at aquaculture systems Action Link

Use acoustic devices at aquaculture systems

A before-and-after, site comparison study in 2010–2012 at a salmon Salmo salar farm in the North Atlantic Ocean, Scotland, UK (Götz & Janik 2016) found that deploying an acoustic device reduced predation on caged salmon by grey seals Halichoerus grypus and harbour seals Phoca vitulina. Fewer salmon were lost to seal predation while an acoustic device was deployed (0–70 fish/month) compared to before (97–104 fish/month) or after (4–9 fish/month) the device was deployed or at two control sites without acoustic devices (2–238 fish/month; 0–99 fish/month). No seal predation occurred during 10 of 12.5 months in which the acoustic device was deployed, whereas seal predation occurred during each of eight months at one control site without an acoustic device and six of seven months at the other. From January 2011 to February 2012, an acoustic device with 2–4 transducers (emitting 200 ms pulses at random intervals) was deployed at the centre of a salmon farm comprising a grid of 2 x 4 rectangular steel cages. Control sites were two salmon farms (with two rows or grids of 6–9 cages) without acoustic devices. In 2010–2012, salmon losses to seal predation (dead fish with bite wounds) were counted during 2.5 months before, 12.5 months during and 3 months after the acoustic device was deployed and during 7–8 months at the two control sites.

(Summarised by: Anna Berthinussen)
Use acoustic devices at aquaculture systems

A before-and-after study in 2011 at a salmon Salmo salar farm in the North Atlantic Ocean, Scotland, UK (Götz & Janik 2016) found that deploying an acoustic device reduced predation on caged salmon by grey seals Halichoerus grypus and harbour seals Phoca vitulina. Fewer salmon were lost to seal predation while an acoustic device was deployed (0–10 fish/cage) compared to before the device was deployed (27–72 fish/cage). In May 2011, an acoustic device with a single transducer (emitting 200 ms pulses at random intervals) was deployed at a salmon farm (two rows of nine cages). Two cages on the farm were stocked with fish. Salmon losses (dead fish with bite wounds) were counted and removed from each of the two cages every 6–8 days during four weeks before and two weeks after the acoustic device was deployed.