The primary job of the men and women who work in the salmon farming industry is to rear healthy fish. Scottish salmon is the UK’s largest food export, as well as being a healthy source of food for our own population.
Salmon farmers encounter a variety of challenges to their goal of rearing healthy fish and one of those is seal attacks on their salmon stocks.
Seals and salmon
The seal population has risen dramatically and seals are highly efficient predators.
The damage seals cause to salmon is severe and extensive, killing many fish – an example is seen in the image below.
Seals kill by taking single bites out of each fish then leaving them to die. On occasions a single seal attack might cause the death of hundreds of fish.
Even those fish which escape attack suffer considerable stress and this can lead to hundreds of further deaths.
The salmon farming industry has an aspiration to reduce the number of seals shot to zero, with shooting a last resort following the detailed regulatory protocol (outlined below).
The number of seals shot is reported to Scottish Government and published online quarterly. These records have been made public since 2011.
There was an overall reduction in the level of shooting in 2017: 49 seals were shot across 200 fish farms, 25% lower compared to 2016 and over 84% lower compared to 2011 figures.
We are progressing very effectively towards zero.
Code of Good Practice
Farmers use the industry’s Code of Good Practice guidelines to ensure that they protect their fish from predators in a number of ways. For example, farmers often use “seal blinds” at the bottom of the pens, made from very small mesh net to prevent the seals seeing any fish in the bottom of the pen; around the pens nets are also heavily tensioned to make it as difficult as possible for seals to push the netting to get at the fish; acoustic devices (ADD – acoustic deterrent devices) emit a high pitched noise to scare seals away if they start attacking the salmon.
A pilot study using two different designs of netting together is proving successful.
Research and innovation continues to find new ways to deter seals. Much of this work is carried out at the Sea Mammal Research Unit (SMRU) at St Andrews University.
These methods mean that only occasionally does a seal attack a farm. If that does happen, each farmer has to consider how to protect the salmon. This is required under the Animal Health and Welfare (Scotland) Act 2006.
Evidence and legal requirements
If all these actions do not deter a seal from attacking fish in a pen, then the farmer has to consider shooting the seal as a last resort. Before that, they have to provide evidence to senior managers that all the methods are in place and have proved unsuccessful in deterring this seal. They need to show evidence that the seal continues to attack the salmon. Only then might a decision be taken to shoot a seal in accordance with the licensing scheme introduced in the Marine (Scotland) Act 2010.
The licensing system is applicable to fish farmers, salmon netting stations and river fisheries. In order to be granted a licence, Scottish Government must be satisfied that each farm has a comprehensive predator management plan with appropriate deterrents in place, with shooting seals to protect farmed salmon welfare a matter of last resort.
The recovery of shot seals is important too and companies endeavour to do this where possible and when the safety of their staff is not put at risk. In some cases the carcasses may be impossible to recover and sink.