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SUSTAINABILITY LIBRARY 2023 Biodiversity Escapes


The Group invests a considerable amount of resources in optimizing equipment and routines specifically to avoid accidental release of fish.

The Group invests a considerable amount of resources in optimizing equipment and routines specifically to avoid accidental release of fish.  


We operate in areas where wild populations of Atlantic salmon also exist, and release of farmed salmon could interfere with the genetics of local populations 


Wild salmon is the only species categorized by IUCN as near threatened with habitats affected by our operation along the Norwegian coast. Lerøy has initiated appropriate steps to avoid harm and prevent extinction of wild salmon (Salmo salar). We have implemented measures to prevent escapes, biosecurity procedures and action towards sealice infestation. In 2023 we started implementing semiclosed technology where we either submerge the cage or seal the cage to avoid lice floating in the surface o fcoastal water to contaminate the fish, which again could contaminate wild salmonids.

Escape incidents can cause Lerøy financial consequences in the form of fines, reduced income and, in the worst case, a lack of capital. Repeated escape incidents could also affect the company's reputation. Fish from aquaculture that escape can find their way into the rivers where wild salmon stocks live. This can create a risk of affecting species diversity in the rivers. There will be a very low risk of any organic or inorganic impact on environmental conditions. Escaped fish from our company will have very little impact on people or human rights.


Our ambition in this area

Lerøy Seafood Group has a vision of zero escapees. 

How we work in the area/ what actions we have taken

Significant measures have been implemented to prevent escape at LSG's farming localities. The Group has invested heavily in both technology, control systems and development of new routines to prevent escape.  

All Lerøy's facilities comply with technical standard NS 9415:2009 Marine fish farms. These requirements are specified in the NYTEK regulation that governs marine fish farms, all main components, structural elements for mooring and extra equipment. 

Actual incidents of accidental release triggers measures determined in the contingency plan and are reported in our Quality management system and to the Directorate of Fisheries, as are events that may lead to accidental release. 

Norwegian Directorate of Fisheries and published on the following website. 


How we measure our impact

Research has shown that escaped fish from aquaculture can have a negative impact on wild salmon that live in rivers in Norway. The Norwegian Institute of Marine Research and various interest organizations monitor wild salmon and publish reports showing the status of the various species of wild salmon. 

The national impact of escape of farmed salmon in watercourses is also measured by different projects like: The national monitoring program for farmed salmon escapees in watercourses. 

Lerøy follows developments closely and we do our utmost every day to prevent that fish escape from our locations. 

The Group controls the number of fish in cages at each facility. The number of fish released to each sea cage from the smolt facility is counted according to the number of vaccinations minus dead fish prior to release. All fish that is taken out of the cage after release are logged daily. When an unknown number of fish escape from the cage, a well boat is used to count the remaining fish, and by comparing the well boat count with the marine farm's own figures an estimate of the number of escapees is made. 

Targets and results 


Target 2024: Zero escapees 











Date #fish escaped What happend? Company Location Estimated cost
16.04.2023 11 Hole in net (*1) Lerøy Sjøtroll Angelskår 500 000
21.08.2023 16 Hole in net (*2) Lerøy Midt  Hogsnes 500 000
31.08.2023 15000 Lice treatment/pumping (*3) Lerøy Sjøtroll Naveide 1 500 000
27.11.2023 2 Handling (*4) Sjøtroll Havbruk Djupvika 500 000
06.12.2023 1 Lice treatment/pumping (*5) Sjøtroll Havbruk Flatøyflu 500 000
  15 030       3 500 000


In April 2023 Lerøy Sjøtroll had an escape incident at farm location Angelskår where 11 trout escaped. A small whole in the net was detected at a routine inspection and 11 trouts were catught in a recapture net set out after the hole was detected. An investigation team consisting of operations manager, team manager, regional manager, operations manager treatment, operations manager, service manager and production manager did not give any clear root cause or learning points.

In August Lerøy had 2 incidents; one at Lerøy Midt farm location Hogses, and one at Lerøy Sjøtroll farm location Naveide. At Hogsnes 16 salmon escaped from a wellboat during a delousing operation. The well boat had a disconnected return hose causing 16 fish to escape. The incident was discovered by personnel on the workboat, operation was immediately stopped and 3 recapture nets were deployed. No fish were recaptured. The nvestigation team has identified human failure to be the root cause. More training and new control points have been implemented.
At Lerøy Sjøtroll farm location Naveide 15000 fish escaped through a rift in the net discovered after a routine inspection by an ROV. Both the Directory of Fisheries and a safety group from Lerøy visited the location to identify the cause of the hole in the net. Neither weather conditions nor any mechanical devices could cause the damage. During the period of the incident several mackerel sturgeon were observed in the area, both the Directory of Fisheries and the safety group from Lerøy identified this as the possible cause of the rift, no learning points identified. The Final number of fish escaped will be verified at harvest.

In November two fish escaped during lice treatment on a chartered vessel. The two fish escaped through a water separator, because of a loose weld in the grate. This caused fish to enter the filter and it overflowed. After the incident the procedure has been changed, so that the grate must be examined before each treatment and escape nets must be put around the separator.

In December one fish escaped during removal of weak fish form a cage using a hand net. The fish bounced out of the net and escaped. The reason was that the hand net was too small. New, larger rakes have been purchased to prevent recurrence.


Action taken due to results

Improvements have been made to secure use of safety measures when capturing fish for delousing and when returning fish to the cage after counting sea lice, to minimise the possibility of escape. 

Lerøy has collaborated with other businesses to establish a new company, Sporbarhet AS. The aim is to ensure efficient traceability services for salmon to prevent escapees with no known origin. The tracking services currently being developed are based on genotyping of all male fish used for breeding and further element analyses to distinguish between fish with the same genetic origins. 

We have implemented the NYTEK standard (minimum technical requirement) and we continuously work together with our suppliers to improve and develop new and better equipment. This is to ensure that all our farms have access to equipment of the highest possible technical standards.  

Risk analysis and several written procedures helps us operate our farms safely, including to prevent escapes. Among other specific measures, we regularly check the technical condition of moorings, facilities, vessels, and equipment, we make use of divers and ROVs to check pen farming nets and employees are trained in prevention of escapes.