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SUSTAINABILITY LIBRARY 2023 Fish health and fish welfare Antibiotics



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.


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 close to zero 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 2024: Annual use of antibiotics in the Group: 0 kg

Annual use of antibiotics in the group



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18,99 kg

*See result 2020


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*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.  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: 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: 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 close to zero 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.