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SUSTAINABILITY LIBRARY 2025 Fish health and fish welfare
SUSTAINABILITY LIBRARY 2025

Fish health and fish welfare

Fish health and fish welfare

For the Group, fish welfare involves protecting fish against unnecessary stress and impact.

Challenges

Farming fish entails responsibility for ensuring that the fish have the best possible conditions. The challenge is to provide for the best possible way to protect and ensure fish health and welfare. The most significant challenges in recent years have been injuries from sea lice treatments, Cardiomyopathy syndrome, bacterial diseases and gill disease.

Impacts: 

If the Group’s farming operations are not managed in a sound and responsible manner, this may result in direct negative impacts on fish welfare and species diversity. In severe cases, such impacts may lead to regulatory sanctions, financial penalties, reduced income, constrained access to capital, and reputational damage.
Inadequate management may also increase the risk of adverse effects on biodiversity, including impacts on species diversity in Norwegian rivers where wild salmon spawn, as well as welfare challenges for farmed fish. 

Our ambitions in this area

The Group’s ambition is for fish in its cages to thrive under conditions that minimise unnecessary stress and negative impacts. The Group acknowledges the ethical responsibility associated with aquaculture and integrates this responsibility into its operational practices.
The Group aims to apply standardised procedures throughout the production cycle and to continuously update these procedures in line with new scientific knowledge and operational experience. To enable this, the organisation facilitates rapid and efficient access to relevant knowledge across all levels of the business.

Main goals

 

  • Our goal is to achieve the highest possible survival rate throughout the entire production cycle for salmon and trout.
  • No disease and good fish welfare

Health

The key objective regarding fish health is to make sure that as many fish survive until slaughter.

Measures to improve fish health include:

  • Selective breeding programmes
  • Screening of brood stock
  • Risk assessment and biosafety
  • Vaccination against a variety of bacterial and viral agents
  • Early diagnosis and treatment
  • Use of functional feeds
  • Reducing sea lice exposure using semi closed- or submersible cages, and lazer technology

Welfare

The Group is working to fulfil the 5 aspects of animal welfare, commonly known as the “Five Freedoms”, for all our fish.

Our fish welfare initiatives are comprehensive and cover every part of our farming value chain.

Mandatory fish welfare training for all staff comprise legislation, animal welfare, fish health biology, stress, sedation and euthanasia. Other topics covered are natural behaviour, environmental requirements, water quality and physiology. Based on this knowledge, staff are also trained in internal fish handling protocols and policies.

Welfare indicators are used throughout the production cycle. The fish is either transported to harvest stations, or harvested on specialized vessels which perform the same functions onboard. At harvest stations and vessels, welfare indicators are used to monitor the fish prior to, and after stunning and bleeding. All our harvest stations and vessels use either electrical or percussive stunning for anaesthesia. This procedure is then followed by bleeding the fish. Bleeding is performed either manually or with robotic systems. Indicators such as eye reflex and operculum movements are monitored and recorded daily. The effect of anaesthesia and bleeding is monitored, and in case of insufficient effect, a reserve system is used. In case of loss of power, an emergency power supply will help evacuating the fish from the rig.

Lerøy does not use routine mutilation as part of its animal husbandry. In salmon and trout farming, removal of the adipose is seldom used for research purposes to distinguish between individuals or groups. In any case, the procedure must be approved by the Norwegian Food Safety Authority and done in accordance with relevant regulations on fish health and welfare. 

In case of the need to euthanize fish on the farming site, the fish is anaesthetized with an approved anaesthetic or by percussion followed by bleeding out. Farm personnel are trained in fish welfare at least every 5 years. In addition, they are guided by fish health professionals, who visit the farm at least monthly.

During transportation of fish in well boats, there is implemented a risk-based water quality monitoring and control program. This continuous monitoring includes parameters such as fish behaviour, temperature, dissolved oxygen and pH. Limit values are set according to duration of transport, density in tanks and size of the fish. Prior to transportation, the health of the fish is assessed and action plans are ready should fish welfare degrade during transport. 

During recent years, increased use of sensor and camera technology in our pens has given us the ability to monitor a range of observable welfare metrics on a daily basis. The metrics are based on the Fishwell standard, and include scores on skin health, deformities, fin damages, eye status and maturation. This is in addition to daily monitoring of environmental parameters at the farming sites such as oxygen, salinity, temperature, potential predators and other parameters. 

For threats to fish welfare in general, the Group uses 
monitoring systems and seeks to maintain a state 
of constant readiness. This includes continuous 
surveillance of water quality, fish health, and 
environmental conditions to detect potential issues 
early. Rapid response protocols are established at 
the level of the individual site to mitigate the impact 
of unexpected events, such as disease outbreaks, 
harmful algal blooms and environmental conditions such as hypoxia or extreme temperatures (i.e. heat stress). Regular training for staff on emergency procedures further enhance the Group's ability to protect fish welfare and ensure operational 
continuity.  

How we work in the area

Throughout the year, we have meetings, email correspondence and conversations with various stakeholders where we have presentations and discussions related to the areas where we have or can have a potential impact. We also attend conferences and meetings where we meet and discuss. Through this form of dialogue, we gain insight into what stakeholders are concerned with and feedback on what they think about the way we work, measures we have initiated and what they think we should focus on going forward. Through various forms of benchmark surveys, we also receive feedback on what stakeholders think about our measures and their implementation. The Group strives to minimise handling operations of live fish. As little handling as possible improves fish health and welfare, which is an important objective for the Group.

We use procedures as management tools for our production. The procedures help us to standardise events at each life stage, and they are updated as soon as we gain new knowledge regarding fish welfare. In this way, the entire organization acquires the new knowledge quickly and efficiently.

The vast majority Leroy salmon and trout production sites  are certified according to welfare standards set in GlobalG.A.P. or ASC.

See section Sealice for information regarding semi-closed and submersible cages.

Smolt production

Pumps, transportation pipes, sorting equipment and vaccination equipment are checked at regular intervals and any damage or defects are repaired before use.

During major operations such as vaccination and sorting, the fish is checked for any damage at regular intervals to detect any defects of equipment.

All components used during sea transfer are checked regularly. If situations arise where an increased incidence of mechanically inflicted damage is registered, delivery is stopped until the cause of the damage has been investigated and corrected.

On-growing phase

During sea transfer, dead fish are controlled for mechanical damage that may have been inflicted during transport. If it turns out that there is presence of mechanically inflicted wounds, a thorough review of the delivery process will be taken.

When fish are crowded during various forms of handling, we have our own handling procedures describing how this is to be carried out and what equipment to use to ensure fish welfare. To reduce the amount of stress on the fish, crowding is kept at a minimum and is monitored by trained personel. For grading, passive grading ('Shetlandsrist') is also used to ensure fish welfare during the procedure. 

In all non-medical lice treatments, welfare screening of the fish is performed before and after treatment. In this way, we have documentation of the impacts for the fish, and whether measures may need to be taken to reduce negative consequences.

All of our on-growing sites take part in a zone-based cooperation with other farmers. In all regions where the Group has operations, fallowing, washing/disinfection and restocking are coordinated in zones every second year. This cooperation also involves coordination of operations, collaboration relating to lice, disease management and other issues where the solution to the problem requires a joint, coordinated effort.

Disease Management

Disease management is of essential importance for all animal farming. Within the Group, disease management is based on a preventive operational practice, where the primary goal is to prevent problems before they occur.

Our work on disease management is based on recognized principles. These are in turn based on biological know-how and attitudes, in which training for our employees and a live internal control system lay the foundations for operations. 

Disease prevention and management are monitored by fish health professionals (authorized animal health personnel), who also play key roles related to Lerøy's continuous learning and development of best operational practice.

We aim to farm fish under production conditions that safeguard the biological requirements of all species. Density and water quality parameters, such as temperature, salinity and oxygen shall be adapted to the requirements for fish at different life stages. We operate a specific vaccination program and vaccinate all our farmed fish before sea transfer.

The main target for fish health and welfare is to increase fish survival rates throughout the production value chain. All employees involved in handling live fish undergo training focusing on fish welfare.

Fish welfare is developed and monitored by keeping use of medicines to a minimum, with careful assessment of use, using only approved medicines which have documented environmental impact in accordance with the requirements of The Norwegian Medicines Agency, monitoring and documenting tolerance, and following up biological feed factors if administered by feed.

Use Of Medication

Medication is used only when this is deemed appropriate and necessary.

We exclusively make use of licensed products, and all medicine prescriptions are issued by authorized animal health personnel. Lerøy Seafood Group currently employs over 20 fish health professionals (authorized animal health personnel).

Policy: Use of medication

Cleaner Fish

Lerøy has in recent years shifted its strategy for sea lice management with an increased focus on preventive technology. As a result, we have significantly scaled down our production and use of cleaner fish. In the event of cleaner fish being used in our farms, the fish are cared for with the same high standards of welfare as our salmon and trout by dedicated personnel. 

How we measure our impact

On a daily basis, all facilities electronically register the number of dead fish and the likely cause of death. Dead fish are collected and delivered for silage, which in turn is included in animal feed for other species.

We calculate a fish welfare score before and after treatment for all non-medicinal delousing. This provides us with documentation of the scope of the impact, and whether we have to take action to reduce the negative consequences.

When using delousing agents and other pharmaceuticals, there are strict routines for how these should be handled. Personnel who will handle the funds have received training in how to handle the substances.

The fish are monitored throughout every part of the slaughter process by personnel who have received the obligatory training in fish welfare. All fish are anaesthetised before slaughter, either by electric shock or percussive stunning. The system and method for slaughter require the follow-up of the Norwegian Food Safety Authority. Every day before starting slaughter procedures, the fish are checked and logged to verify a sufficient level of anaesthetisation.

Targets and results

Target 2025: Survival in sea, last 12 months according to GSI: 96 % 

Result 2025: 93,7 % 

Increased survival is a result of the companys strategi to produce more robust smolt and shielded/submerged technology.

 

What action has been taken

The Group have many ongoing projects and initiatives aiming to improve health and welfare of our fish, and thus increasing survival rates. Examples of recent measures implemented to reduce mortality:

  • Investment in new semiclosed and submersible technology
  • Risk analysis and management of time of sea transfer
  • Implementation of new vaccine against bacterial wounds
  • Use of functional feeds to improve wound healing
  • Several improvements in onshore production to ensure a more robust smolt
  • Investments in post-smolt facilities (RAS) to reduce production time at sea

We make use of procedures as governance tools for production. These procedures help us standardise the processes to which the fish are subjected, and they are updated as soon as we obtain new knowledge that has to be taken into account. As such, the entire organisation has rapid and efficient access to new knowledge.

R&D Projects Within Fish Welfare and Farming

The group participates in many different research projects in order to be at the forefront in terms of the best possible fish health and to implement new technology and expertise as soon as possible.

The various projects can be roughly divided into 3 different areas:

  • Sea lice management
  • Vaccines and functional feeds
  • Risk management, biosecurity and production improvements

Most of our ongoing projects fall into one of these groups.

A number of projects have been implemented to improve fish health and fish welfare. These include:

  • Feed ingredients and resistance to CMS: Aims to investigate if use of specific feed ingredients can improve survival and growth after CMS diagnosis.
  • Lerøy internal wound projects: Different projects that aim to reduce prevalence of bacterial wound-infections. In recent years, several projects has been carried out to identify risk factors for wound development on both large fish and fish recently released to sea.
  • Vaccine trials: Contribute to development of new and more effective vaccines.
  • R&D license and Prolaks project: Aims to map effect of post smolt size on health, welfare and performance.
  • FHF 901736 – Knowledge base of biological relevant welfare indicators for salmon in aquaculture (BIORELEVANS): Aims to provide necessary biological knowledge for establishing health- and welfare data from automatic scanning. Establish limits for when different indicators reflect a normal situation.
  • FHF 901434 - Tenacibaculum spp. Project: Aims to increase knowledge of tenacibaculosis, identify risk factors of disease, describe toxin production and perform trials with use of toxins as antigens in vaccines.
  • Lerøy internal robust smolt project: Aims to find the causes of why some smolts develop poorly after sea transfer.
  • FHF 901680 Pasteurellosis in Norwegian salmon: Characterizing, epidemiology and dynamics of pathogen transmission.
  • Prevention of salmon associated Pasteurella project: Aims to find effective preventive treatment against Pasteurella.
  • Pathogen project: Aims to map infection pressure of a number of pathogens during the production cycle, including finding risk levels for transmission of disease by vectors.
  • Welfare project: Aims to map fish welfare related to different “non-medicinal” treatments.
  • Lerøy internal project: Aims to increase survival rate and robustness of fish in smolt production.
  • Lerøy internal project: Aims to increase survival rate and growth in sea.
  • Lerøy internal project: Aims to find measures to reduce risk for mechanical injuries to fish.
  • NFR 326980 Welfare Severity: frameworks for classifying the welfare of farmed Atlantic salmon based upon the principles of severity assesment
  • FHF 901835 Best practice measures to prevent winter ulcers: aims to identify best practice for handling and mapping wound risk related to handling.
  • FHF 901838 Wound bacteria in sea-based salmon farming: aims to identify to what extent the risk of ulcer development depends on the composition of marine bacterial communities

The Group aims to improve the health and welfare of our fish. Ensuring good health and welfare is first and foremost an ethical responsibility, however reduced health and welfare can also negatively impact our biological and economic results. In order to ensure good health and welfare, the Group actively works to make sure that the fish thrive, grow and survive.

Improved fish health is monitored by number of disease outbreaks and survival rates.

What measures do we take to handle the fish as gently as possible

The Group strive to minimize handling operations of live fish. As little handling as possible improves fish health and welfare , which is an important objective for the Group.

We use procedures as management tools for our production. The procedures help us to standardize events at each life stage, and they are updated as soon as we gain new crucial knowledge regarding fish welfare. In this way, the entire organization acquires the new knowledge quickly and efficiently.

Smolt:

Pumps, transportation pipes, sorting equipment and vaccination equipment are checked at regular intervals and any damage or defects are repaired before use.

During major operations such as vaccination and sorting, the fish is checked for any damage at regular intervals to detect any defects of equipment.

All components used during sea transfer are checked regularly. If situations arise where an increased incidence of mechanically inflicted damage is registered, delivery is stopped until the cause of the damage has been investigated and corrected.

Ongrowing stages:

During sea transfer, dead fish are controlled for mechanical damage that may have been inflicted in connection with the transport. If it turns out that there is presence of mechanically inflicted wounds, a review of the delivery process will be taken.

When fish are crowded during various forms of handling, we have our own handling policies describing how this is to be carried out to ensure fish welfare.

In all non-medical lice treatments, welfare screening of the fish is performed before and after it has been treated. In this way, we have documentation of the impacts for the fish, and whether measures may need to be taken to reduce the negative consequences or not.

Disease management

Disease management is of essential importance for all animal farming. Within the Group, disease  management is based on a preventive operational practice, where the primary goal is to prevent problems before they occur.

Our work on disease management is based on  recognized principles. These are in turn based on  biological know-how and attitudes, in which training for our employees and a live internal control system lay the foundations for operations. 

Disease prevention and management are monitored by fish health professionals (authorized animal health personnel), who also play key roles related to Lerøy's continuous learning  and development of best operational practice.

We aim to farm fish under production conditions that safeguard the biological requirements of all species. Density and water quality parameters, such as temperature, salinity and oxygen shall be adapted to the requirements for fish at different life stages. We operate a specific vaccination program and vaccinate all our farmed fish before sea transfer.

The main target for fish health and welfare is to increase fish survival rates throughout the production value chain.  Salmon mortality rates due to viral diseases has decresed by 19,4% during the last two years. All employees involved in handling live fish undergo training focusing on fish welfare.

Fish welfare is developed and monitored by keeping use of  medicines to a minimum, with careful assessment of use, using only approved medicines which have documented environmental impact in accordance with the  requirements of The Norwegian Medicines Agency, monitoring and documenting tolerance, and  following up biological feed factors.

Use of medication

Medication is used only when this is deemed appropriate and necessary.

We exclusively make use of licensed products, and all medicine prescriptions are issued by authorized animal health personnel. Lerøy Seafood Group currently employes 20-30 fish health professionals (authorized animal health personnel). 

Antibiotics

Challenges

Excessive use of antibiotics can result in antibiotic resistance in some areas, a major risk factor for health and for fighting diseases, particularly for humans.

In general, food production from animals require the use of medicines to treat diseases, not least with a view to animal welfare.  If not controlled, the use of antibiotics and other medicines in conventional fish farms could contribute to an undesired and negative affect on humans and the environment.

Impacts 

If disease is detected on our fish and if the fish must be given antibiotics for fish welfare reasons, this will also lead to an increased risk of fish mortality as well as increased costs for Lerøy. The use of antibiotics, on the instructions of Lerøy`s fish health personnel, will have very little risk of causing any kind of damage to the environment. Without proper training and protective equipment, the use of antibiotics can ultimately cause intolerance in personnel who handle antibiotics. Note that the volumes that Lerøy has used during the 15 last years are extremely low.

Our ambitions in this area

Lerøy Seafood Group avoids unnecessary use of all antibiotics, including MIAs, CIAs and HPCIAs and veterinary antibiotics, in production of all fish for consumption. We aim to achieve this goal via organization-wide measures involving disease management, including preventive operational practice, 100 % vaccination, early diagnosis and appropriate measures to handle outbreaks.

How we work in the area

The use of antibiotics is very low in the Norwegian fish farming industry. Lerøy Seafood Group applies a very restrictive policy when it comes to use of antibiotics, and use is only on exception and to safeguard fish health. Antibiotics are seen as the last resort, only applied in situations where use has been assessed by veterinarians as necessary to handle a confirmed disease-related situation.  The Group´s policy on use of antibiotics is compliant with WHO (World Health Organization) guidelines on use of Medically Important Antimicrobials in food producing animals and the WHO list of Critically Important Antimicrobials for Human Medicine.

The Group has specifications for special brands saying that there is not used any kind of antibiotics during the production time. These brands are certified by a 3rd party.

All medicines used must be prescribed by authorised fish health personnel. Before starting medication, a risk analysis is carried out to assess measures not involving medicines, and the impact on any vulnerable habitats and species close to the facility.

Risk assessment and measures are in place to prevent any risk of employees developing antibiotic resistance.

How we measure our impact

All use of medicines is logged in our own production management system. Details such as the name of the person who prescribed the medicine, approved assistant, active substances, quantity, treatment period and retention period for the fish are all registered each time treatment is administered.

Environmental surveys are conducted at least once a year in the zone surrounding each facility. These surveys are conducted by an independent company. The analyses are in three parts: fauna, chemical and sensory. The analyses result in a score from 1 to 4, where 1 is the best result. If the score is 3 or 4, action must be taken to improve conditions at the facility. Similar and more extensive surveys are conducted outside the immediate surroundings at least every five years.

Targets and results

Target 2025: Annual use of antibiotics in the Group: 0 kg

Annual use of antibiotics in the group

Comment

2025

0 kg

 

2024

219 kg

* see result 2024

2023 

0 kg

-           

2022

0 kg

-           

2021

0 kg

-           

2020

18,99 kg

*See result 2020

2019

0 kg

-           

*Result 2024: One treatment with antibiotics with 219kg active 
substance (Florfenicol) used due to bacterial infections. 
Antibiotics are used for the welfare of the fish

*Result 2020: 18,99 kg One treatment with 18.99 kilo total, which is 0,08mg Florfenikol/kg produced fish. This was treatment administered to small, newly released fish, for a bacterial infection, Tenacibaculum sp. and Moritella viscosa.

Action taken due to results

Lerøy avoids unnecessary use of antimicrobial agents. To achieve this, a number of different preventive measures are implemented and are part of a preventive operating practice including vaccination, risk management, disease control, structural measures, early diagnoses etc.  The most significant measure for reducing the need for antibiotics in recent years is the introduction of a new vaccine against winter ulcers. 

A number of preventive projects have been initiated to prevent future use of antibiotics. These include:

Tenacibaculum spp. as the cause of atypical winter wounds on Norwegian farmed salmon – Norwegian Seafood Research Fund (FHF) project:

https://www.fhf.no/prosjekter/prosjektbasen/901434 Project period: 01.10.2017-30.09.2021. The aim of the project is to identify risk factors for the outbreak of Tenacibaculosis and to characterise toxin production in Tenacibaculosis spp. The project also aims to test “proof of principle” for the use of toxins as antigens in vaccines.

Limit the effect of tenacibaculosis in Norwegian fish farming (LimiT) – Norwegian Seafood Research Fund (FHF) project: https://www.fhf.no/prosjekter/prosjektbasen/901433/ Start/finish: 10.10.2017 – 15.12.2020. The goal with this project has been to gain a better understanding of how a disease or illness progresses, and to identify virulence factors in the bacteria. Trials involving infection have shown that the skin on smolt that have been kept in waters with lower salinity (26 per thousand) than normal sea water prior to release to sea may be better able to combat infection. Comparisons over time in the infection model demonstrate that the skin is in significant development, and that this most likely affects the outcome of the infection. This implies e.g., that the outcome of exposure to skin pathogens will largely be affected by the post-smolt phase of the skin. The results indicate that the industry may be able to reduce the consequences of tenacibaculosis by exposing the smolt to lower salinities during a period prior to release to sea.

FHF 901835 Best practice measures to prevent winter ulcers: aims to identify best practice for handling and mapping wound risk related to handling.

Lerøy internal wound projects: Different projects that aims to reduce prevalence of bacterial wound-infections. In 2020, a project was implemented to identify risk factors for wound development on large fish and fish recently released to sea.

Vaccine trials: To contribute to development of new/more effective vaccines.

The use of antibiotics is very low in the Norwegian fish farming industry. Lerøy Seafood Group applies a very restrictive policy when it comes to use of antibiotics, and use is only on exception and to safeguard fish health.

Sea lice

Challenges

Salmon and trout farming entails a relatively higher level of host density compared to in the wild. Infection pressure of wild salmon stocks with sea lice from farmed salmon is one of the main challenges in terms of environmentally sustainable aquaculture.

Due to the host density in farming, Lerøy attempts to keep average numbers of mature female sea lice as low as possible throughout production. Controlling sea lice levels entails higher costs and have the highest priority in Lerøy.

Impacts 

Salmon lice live naturally in the sea and will be able to use our fish in aquaculture as host animals. It is important for Lerøy that we monitor the level of lice in the sea and on fish when the fish is under production. Undesirable quantities of lice will increase the risk that possibly escaped fish from our farms, and smolts that are migrating from the river and passes our farms to the sea, may be attacked by lice. If the lice surcharge becomes too high on our fish, it may exceed the limit values in Norwegian regulations and lead to increased costs for the company, fines, downgrading of fish, reduced fish welfare and, in worse case, fish mortality. Lice infestation on wild smolt could have a negative impact on this species.

Our ambitions in this area

The Group´s efforts to control salmon lice follow the principles of an IPM strategy to control salmon lice and keep the numbers at a low level in the long term. The overall goal is to reduce any negative impact on the environment and the need for active interventions.

The overall principles underlying this control strategy includes establishing acceptable levels (see details in Policy), preventive measures (as structural measures relating to use of locality, coordinated operations over larger geographical areas, zone collaboration, fallow periods in between production cycles, smolt quality and smolt weight as measures to reduce period of exposure, use of various types of physical barriers, (e.g. skirts), monitoring, biological control (i.e. cleaner fish) and active interventions.

We work to minimise levels of adult female lice per fish as close to zero as possible.

How we work in the area

We use targeted measures to reduce the number of lice by reducing exposure in the sea. To do so, we produce larger smolt using RAS technology so we can have shorter production periods in the sea. 

Additionally, to counter the burden of sea lice and its effect on fish 
health and welfare, Lerøy is implementing 
shielding technology at selected sites in Lerøy Midt 
and Lerøy Sjøtroll, as well as deploying optical 
delousing equipment in Lerøy Aurora.  While semi-closed solutions are employed at protected sites, submerged cages are 
rolled out at more exposed sites at greater depths. 
Semi-closed solutions have solid barriers in the form 
of steel skirts and/or impermeable tarpaulins 
physically separating the inside of the cages from the 
upper layers of the water column where sea lice are 
most abundant. Closed containment systems 
however, fully separate the fish and water within the 
cage from the surrounding body of water. Pumps 
inside the cages facilitate water flow, drawing water 
from below the “lice belt” while also ensuring proper 
circulation of water within the cage. Submerged 
cages resemble conventional cages and are open in 
the sense that water flow is not obstructed by any 
other barriers than nets. These cages are submerged, 
meaning that the fish are held at certain depth, below 
the “lice belt” with a net ceiling containing an air 
dome supplying the salmon with air to fill its swim 
bladder and exhibit natural behaviour.

Requirements from the authorities provide a definition, at any given time, of the upper maximum limit for fully grown female lice. Lerøy has also established their own limit values to provide guidelines for when to implement preventive and active measures to control sea lice levels.

The average values for lice in the facilities shall be reduced by more than 50% during the period from April to June when compared with the rest of the year. This is when wild salmon migrate as smolt from the rivers to the oceans.

How we measure our impact

Sea lice counts and registration are carried out at a minimum of every seven days for all cages in each facility. This is either done manually by catching the fish in a landing net or automatically by underwater camera technology. If done manually, the fish are anaesthetised in tanks and controlled individually. A representative selection of fish is taken from each cage. Lice are counted in the following categories in terms of stages:

1) Adult female (with and without egg strings)

2) Mobile pre-adults (including adult males)

3) Attached juveniles

An average figure is calculated by totalling the number of all lice from all fish (plus lice in the tank for counting) and dividing this number by the total number of fish studied. The weighted average for the farm is calculated based on sea lice counts and the number of fish in each pen.

Infestation of wild fish by lice from Norwegian fish farms is calculated regionally by the Institute of Marine Research, by counting lice on wild salmon and using modelling. To read the Institute's report for 2023, use the following link: Lakselus – risikovurdering og kunnskapsstatus 2023 | Havforskningsinstituttet (hi.no).

Target and results

Target 2025:

  • reduction of sea lice treatments to 1 150

Limits for levels of adult female lice per fish set by the authorities varies throughout the year and differ depending on region. This is described in detail in the Group´s Policy for control of sea lice.

Norwegian regulations require that the average number of adult female lice per fish per farm must be below the maximum limit of 0,5 at any time. In addition, during spring where smolts typically migrate from the rivers to the ocean, the average number of female lice per fish per farm must be below 0,2.

This period is defined as:

Week 16 up to and including week 21 in Trøndelag County and further south.

Week 21 up to and including week 26 in Nordland County and further north.

  2025 2024   2023 2022
Number of cages treated for lice ( number)  1956 1463 1772 1853

The target of reducing number of sea lice treatments 
to 1 150, relates to the objectives of the fish health 
and fish welfare policy, which is to ensure the health 
and well-being of fish as it is a main driver behind 
reduced welfare in the Group’s farming operations. The 
target is absolute and is measured as the number of 
cages treated for lice during the reporting year. The 
scope of the target includes all Lerøy’s sea-based 
farming in Norway.

Action taken due to results

Lerøy’s efforts to control salmon sea lice shall continue to follow the principles of an IPM strategy to control salmon sea lice and keep the numbers at a low level in the long term. The goal is to reduce the negative impact on the environment and the need for active interventions. Below is a description of the overall principles underlying this control strategy.

Preventive measures: Prevention is the first line of defence, aiming to control the levels of salmon sea lice by making use of passive control mechanisms. The methods utilised depend on local prerequisites and entail use of one or more of the following measures: Structural measures relating to use of locality, zone collaboration, fallow periods in between production cycles, post smolt strategy and different types of physical barriers.

Biological control: cleaner fish represent a method for treatment prevention, and the goal is to reduce the need for active measures.

Non-medicinal methods: These methods are based on different types of measures that do not include the use of medicines. Lerøy makes use of methods within the categories for fresh water, flushing and temperate water.

Medicinal methods: These methods are based on the use of medicines. In cases where medicines are utilised, these shall be 1) prescribed by authorised fish health personnel and 2) evaluated with regards to the risk for fish welfare, food safety, environment and resistance, and 3) where only medicines approved by Norwegian medicines authorities can be used.

New semiclosed technology: Lerøy has made significant investments  in coastal production technology recently. A combination of submersible and semi-closed cages is now being rolled out at selected locations in Lerøy Midt and Lerøy Sjøtroll . We believe this will have a positive impact on fish health, and reduce the lice load. This is because the cages are lowered below lice level in the sea, thus protecting the fish from lice.

Policy: Control of salmon lice

 

 

 

Survival rate

It is an essential goal for us to keep the survival rates as high as possible.

It is an essential goal for us to keep the survival rates as high as possible.  

Lost fish is undesirable both from a fish health and welfare perspective and from a financial perspective. Thus, our goal is to get as many individuals as possible throughout the whole production phase from egg to slaughter. Farming robust smolts, good husbandry, disease control and careful handling are key factors.  

 

Main goal

2025: Survival in sea, last 12 months according to GSI: 96%, Goal survival land : 95%

 

 

2025

2024

2023

2022

2021

2020

2019

Survival in sea (%)

93,7

93,1

91,5

92,5

92,5

92,2

93,4

Survival on land (%)

93,8

94,5

91,3

91,4

88,8

93,5

91,5

Different biological factors contribute to the result, in 2025 delousing treatments and viral diseases where main mortality reasons. The top three causes of mortality in the sea phase 2025 were distributed as follows.

  Biomass (tonnes) Number of fish (mill.)
Delousing treatment 4 380 1,83
Viral diseases 4 797 1,57
Wounds 2 305 1,23

Departments in the Group´s Farming division, contributes to the work to achieve the main goal, by identifying and working towards their own specific goals for survival. This includes land- and sea-farms.   

Read more: This is how Lerøy works with fish welfare

Policy:  Fish health and fish welfare