Seals – a natural predator

Seals are highly efficient predators and when they decide to attack, the damage to salmon in fish farms is severe and extensive.

Most of the time, salmon farms exist happily alongside Scotland’s wide range of marine wildlife. However, from time to time a seal will attack the salmon in the net pens killing many fish.

Seals kill by taking single bites out of each fish then leaving them to die. Even those fish which escape attack suffer considerable stress and often die as a result.

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, he has to provide evidence to his senior manager that all the methods are in place and have proved unsuccessful in deterring this seal. He needs 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. This must only ever be as an act of last resort.

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 appropriate deterrents in place already.

Declining numbers

The number of seals shot is reported to Scottish Government and published online quarterly. These records have been made public since 2011.

In 2016, 49% of all licences shot no seals at all.

There was an overall reduction in the level of shooting in 2016: 10% lower compared to 2015 and over 80% lower compared to 2011 figures.

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