Sealice control

Why it is important to us

Dealing with lice is high on our stakeholders´ agenda due to the potential negative impact on wild populations and farmed salmon’s health and welfare alike. Treating lice is also cost- and resource intensive and high levels imply lower productivity and quality. Improper handling of lice can lead to resistant lice, which again could lead to natural constraints on future growth of the industry. In short: Sea lice management is paramount to secure long-term sustainability of the industry.

Our main principles

Lice levels should stay below Norwegian authorities´ limits in all our fish farms in Norway. We also strive to comply with the same standard in our operations in other countries. To ensure compliance we strive to always be ahead of the lice development through continuous monitoring and response. Delousing efforts should also be balanced with a focus on fish welfare and avoiding resistance. We therefore prioritise non-chemical delousing methods when possible. For the best possible shared response, we will also focus on local cooperation, coordination and transparency with other participants.

Our efforts and achievements

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  • Delousing agent

Fish farming

  • Preventive measures
  • Continous monitoring of levels
  • Balancing chemical and non-chemical treatment
  • Records and follow-up through Fishtalk

A key step in our efforts to prevent and treat against lice is the statutory systematic monitoring of sea lice levels in all our fish farms. The salmon is checked for lice every week at water temperatures above 4 °C. At water temperatures below 4 °C lice is counted every other week, out of consideration for fish health and welfare. Due to less pressure with regards to sea lice in BC, the routine differs slightly. Based on the results, relevant agents are applied. Examples of such measures include conducting lice counts several times a week at high sea lice levels as well as susceptibility testing of sea lice populations before treatment is engaged.

In 2014 we have convened a cross-regional technical group to discuss best practices for managing and monitoring sea lice levels. This group will continue to meet on a regular basis.

Revolving use of the fewest possible chemical agents is extremely important in lice treatment, in order to minimize the development of resistance to current treatment. We have therefore focused on “rolling over” the use of chemical agents and active use of wrasse. In Rogaland we now have extensive experience with the use of wrasse. The natural conditions are not right for the traditional use of wrasse in the other regions, but the last three years we have commenced on projects in an attempt to develop the use of lumpsuckers in Rogaland, Finnmark and Shetland. The results are promising, but there are still some challenges to be resolved before lumpfish are an effective method to control sea lice on salmon. We are also looking into the use of several alternative non-therapeutic sea lice options. There are some technologies that can be deployed against lice. For example in Finnmark and Shetland we have introduced sea lice skirts. We also cooperate with other actors in the regions where we operate to keep sea lice levels low.

Figure 2: Adult female lice per salmon per month for 2014 (Lepeoptheirus salmonis)

Figure 2 shows the average monthly level of sexually mature female lice in each region of Grieg Seafood. Grieg Seafood has defined 0,5 sexually mature females as a threshold for implementation of measures in each region. This is stricter than the national guidelines in the UK and BC. Sea lice levels is still our biggest challenge, although in three out of four regions we have managed to keep the se lice levels relatively constant as compared to 2013. Unfortunately the sea lice challenge grew in Shetland in 2014. This was in part caused by large, pre-harvest salmon, as well as gill problems in some of the localities which meant that these fish could not endure lice treatment. In BC we still face challenges in managing sea lice levels when the wild salmon come back to the coast and up the rivers bringing with them sea lice.

In Rogaland the combination between wrasse and 100% clean nets has been an important factor in keeping sea lice levels low. Good grooming of wrasse is also important, and good hiding places and feeding of wrasse in periods with little lice is important.

In 2014 we have also strengthened monitoring of sea lice levels through monthly reporting and reviews at global management team level.

Figure 3, and figure 4, below shows the amount of medical active substances used in in-bath and in-feed treatments respectively. As the numbers show Finnmark had the lowest sea lice level, but has used the highest amount of active substances in relation to their production level. This has several explanations; in comparison to Rogaland, wrasse is not available in Finnmark. We were furthermore forced to give some «double» treatments in Finnmark when the initial treatment was ineffective. Alternating the treatments also impacted the high level of active substances used this year in Finnmark, in particular with regards to the use of chitin inhibitors for large fish. In Shetland and Rogaland treatments have been limited to in-feed treatments for small fish which has lower levels of active substances.

In Shetland there is a large discrepancy with regards to sea lice levels and the use of active substances. This is because Shetland has mainly relied on the use of hydrogen peroxide (H2O2). H2O2 is a naturally occurring, though potent, oxidising agent that breaks down into H2O (water) and O2 (oxygen) when used in an aquatic environment.

Figure 3: Medicinal in-bath treatments: amount of active pharmaceutical ingredients (APIs) used (grams) per tonne of fish produced (LWE).

Figure 4: *Medicinal in- feed treatments: amount of active pharmaceutical ingredients (API) used (grams) per tonne of fish produced (LWE).

Our ambitions and goals

We have defined a target of not more than an average of 0,5 sexually mature female lice per site. Although this is more stringent than the requirement for localities outside of Norway we want to strive towards the same goal throughout the Group. In Norway our aim is even lower. To ensure that we achieve our goal of combating lice while avoiding resistance, we will continue to make necessary investments to implement the most effective treatment methods. In this work, we have a focus on non-chemical treatments. We have adjusted our plans for managing sea lice levels, and will have a particular focus on managing the levels in Shetland.

Also considering the lice challenge we work to implement common performance indicators and targets comparable across the Group and the industry in general.

We are working on getting more treatments approved and have started a trial application for a new product in BC. We are also looking into the use of alternative mechanical/thermal methods.