Sea lice

Sea lice are one of the biological challenges that we try to control for the good of our fish’s health and wild salmon populations. Here, we explain the importance of addressing sea lice issues and how we monitor and treat sea lice in line with veterinary advice and scientific evidence.

Sea lice are naturally occurring parasites which attach themselves to the salmon and can eventually cause damage to the skin of the salmon’s skin in the wild and in farms. The Lice can multiply quickly in sea farms which makes them a particularly concerning issue for us. If left unchecked, lice can damage, or even kill our fish and potentially risk exposing any wild salmon, near our farms, to parasitic infection. Sea lice present challenges to our fish health and the wider ecosystem, which is why we take our responsibility to control their numbers very seriously. Treatment for sea lice is resource intensive; can add more stress to our fish and is expensive; that’s why we always prefer to prevent sea lice levels from growing to problematic levels. At all times, we are concerned with controlling sea lice levels; ensuring that we remain below the legal limits is our priority but ideally, we seek to keep levels even lower.

Controlling Sea Lice

At Grieg Seafood Shetland we count sea lice levels every week to evaluate the risks that they pose in order to act as quickly and effectively as possible to prevent harmful infestations. We work collaboratively across all our regions to share best practices and we proactively work with neighbouring farms to coordinate responses to local sea lice issues. While it is possible to use medicinal treatments, we only do this when absolutely necessary. Instead we prefer to use preventative measures like sea lice skirts and cleaner fish which naturally prey on sea lice. We also have the option of using non-medical mechanical treatments if suitable to avoid affecting the environment with medicines. If medicines are needed, then they are prescribed by certified veterinary fish health specialists.

Our Results

All Grieg Seafood sites face challenges associated with the unique biological and environmental conditions of their ecosystem. In Shetland, we tend to experience higher levels of sea lice than our sites in Norway. Whenever we record more than two adult female sea lice per fish, we immediately report it to Marine Scotland for monitoring. If we ever record more than six adult female sea lice per fish, then we are legally obligated take action to counteract the problem. However, in practice we would never hope to reach such high levels and would always take action long before then. We have made good progress in reducing sea lice levels and have been able to reduce our reliance on pharmaceuticals by using more environmentally friendly treatment options. However, we acknowledge that sea lice are an ever-present challenge, and we must always assess and improve our methods in line with scientific advice and best practices. While we are pleased with the progress we are making in this area, but we will not allow ourselves to become complacent, we always prioritise fish health and environmental protection.

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