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 shall 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 always to be ahead of lice outbreaks 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 results

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 are checked for lice every week at water temperatures above 4 °C. At water temperatures below 4 °C lice are 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 measures 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.

All regions shall have a comprehensive plan regarding sealice control. In 2015 we have held regular meetings in our interregional technical group to discuss best practices for managing and monitoring lice levels, including the regional plans.

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, and limit the impact on the local environment. 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 during the last four years we have commenced projects attempting to develop the use of lumpsuckers in Rogaland, Finnmark and Shetland, with promising results. We are also looking into the use of several alternative non-therapeutic sea lice options. There are also technological efforts that can be made. For example in Finnmark and Shetland we have introduced sea lice skirts. In BC we in 2015 initiated an application for the use of an alternative treatment. 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 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 Canada. Sealice levels are still our biggest challenge, and in BC, Shetland and Finnmark we unfortunately had increased sea lice levels in 2015 compared to 2014. In Shetland this is mainly due to increased gill damage caused by algal blooms. Gill damage reduces the effectiveness of treatments we are able to use. In BC the sealice levels were higher in 2015 compared to 2014 due to very little rainfall during the winter 2014/2015 and during the spring and summer of 2015. Low precipitation caused reduced freshwater run-off into the sea, and thereby increased salinity, which allowed sealice to thrive. It is nevertheless important to note that sealice levels were low during the relocation period (March to June inclusive). In Finnmark the somewhat higher values are caused by the high ocean temperatures.

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.

Figure 3, and figure 4, below shows the amount of medical active substances used in in-bath and in-feed treatments respectively. Shetland has had an increase in the use of the lice treatment in relation to the production level from 2014 to 2015. This is due to the increased sealice levels, requiring increased treatment. BC has very little use of the treatment, which is due to a deliberate limitation of the number of treatments per year to reduce the risk of sealice becoming resistant to the most commonly used active substances. It is important to notice that sealice levels are managed and kept low during the sensitive wild salmon out migration three month period. In Finnmark we had a small increase in the use of in-bath treatments, but a significant reduction in the use of active substances in feed. This is due to change in use of substances. In Rogaland we have had a reduction in the use of active substances, both in in-bath and in-feed treatments, as we have used other types of treatments, including increased use of hydrogen peroxide.


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. For green licences the goal is as low as 0.25 sexually mature female lice per site. In addition we have an overall goal of 50% reduction in treatments over the period 2015-2018.

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 also look at the possibility of using different mechanical/thermal methods. In Finnmark, for example, we will expand the use of sealice skirts and lumpfish considerably in 2016. All of the cages in the Alta and Loppa locations will have sealice skirts, and 1/3 of the sites in Hammerfest and Nordkapp. All four sites will use lumpfish. In BC, we will develop a new, updated management plan for sealice control with input from all BC locations. In addition the region will focus on training of employees and best possible use of infrastructure. We also hope to be granted the application for use of the new treatment in BC during the first months of 2016.

GSF is also part of a cluster in Bergen, NCE. An expert group with delegates from the fish farming industry as well as from research institutions was recently appointed. The group will develop a protocol for “best practice” to achieve minimization of lice.