Before stocking a production site, approval is required from a number of official and private bodies. Furthermore, approval requires compliance with numerous analyses, requirements and local conditions.

These approvals are given after mapping and compliance of ecological status, spawning areas for marine species, diversity, and presence of endangered species in the region.

One of the assessments carried out both prior to approval for operations at a location and during fish farming at the facility is a so-called MOM-B evaluation.

MOM-B stands for:

M – matfiskanlegg (production facility) 

O – overvåkning (monitoring)

M – modellering (modelling)


A MOM-B evaluation is carried out by a third party  and involves extraction of samples from the seabed  under and around the cages in a facility.

The analysis has three parts:

  • Fauna investigation
  • Chemical investigation (pH and oxidation reduction potential)
  • Sensory investigation (gas, color, odor, consistency, dredge volume and mud depth)

All parameters are allocated a score according to  how much sediment is affected by the organic  substance. The distinction between acceptable and  unacceptable sediment condition is set to the highest  accumulation that allows burrowing benthic organisms  to live in the sediment. The analyses are carried out  when production of one generation is at its peak. 

On the basis of these investigations, the individual location receives a score, which also provides an indication of when the next MOM-B investigation should be carried out. A poor score often requires more frequent seabed investigations than a good  score. In addition to MOM-B, analyses are also conducted locally at individual facilities. These include measurement of density, oxygen level in the sea, currents, water quality, visibility, dives under the facility etc.

Each facility is also linked with neighboring  facilities in a zone-based cooperation to work together on topics such as lice and preventing accidental release, spread of disease, outbreaks of disease etc. MOM-B samples must always be taken before releasing fish to a location.

If the score is 3 or 4, fish must not be released without an additional evaluation of the  status of the location, describing the reason for the lack of restitution. If a score of 3 or 4 is reported for a location, a MOM-C sample shall be taken.

Main goal:Average MOM-B max 1.5 per location


In addition to B surveys, MOM C surveys are also conducted at all facilities. The C-survey is a trend monitoring of the bottom conditions in the transition zones from the farming zone and outwards in the recipient. This study is based on mapping of fauna on soft bottoms, which is carried out in accordance with relevant ISO standards. In addition, hydrographic, geological and chemical support parameters are included. These extended trend monitoring outside the local areas is done at least every 5 years, but the frequency may increase based on the condition from each survey.

KPI: Biodiversity


Copper is a naturally occurring chemical element which can be toxic at high levels in the marine environment. Nets are treated with antifouling agents containing copper. However, cleaning of nets is  necessary to ensure good water quality for the farmed  fish. Lerøy Seafood Group uses low-pressure underwater washers to minimise the risk of copper flaking off.

Projects have been implemented to  measure the amount of copper emissions for each wash. Depending on the results, Lerøy Seafood Group will explore alternative methods for keeping the nets clean. At sites where elevated copper amounts have  been detected in the sediments, the Group has started  to use antifouling agents without copper, or has changed the nets as an alternative to in-situ cleaning.

In addition to cleaning in-situ, all nets are cleaned at onshore sites after each production period. Onshore cleaning sites have zero copper emissions, as required  by Norwegian legislation.

Copper impregnation has a positive effect on sea lice and is used as there are currently no adequate alternatives. The Group is actively working with suppliers to develop an alternative to replace copper.

Main goal: Replace antifouling agents that contain copper


As a strategy to minimize infection pressure and environmental impact, all sites are fallowed and washed/disinfected every two years. In all regions where the Group has operations, fallowing and  stocking periods are coordinated in zones, defined by the The Norwegian Food Safety Authority, NFSA and companies in each Area Based Management, ABM scheme.

Every site in a defined coordinated area is fallowed every second year for at least two  months. Within each area-based management area, there is at least a one-month coordinated fallowing period every second year.

In 2020, every marine site was fallowed for more than four months (138 days) on average for the Group. 

Main goal: Average fallowing per location: Minimum 60 days


Fallowed days in average per site

Year Lerøy Aurora Lerøy Midt Lerøy Sjøtroll Total
2014 95 84 134 107
2015 84 94 120 105
2016 111 179 123 141
2017 92 204 125 132
2018 123 158 135 138
2019 227 121 126 140
2020 134 122 161 138


The maximum legislative limit for fish density in a cage is 25 kg/m3 but the results for 2019 were far below this limit, indicating that the fish have plenty of space in the cages.

Fish health and fish welfare are at the core of our operations as a producer of Atlantic salmon and rainbow trout. As such, we are committed to both ethical and statutory obligations governed by Norwegian legislation.

A healthy fish is also a good fish for production and a prerequisite for good financial results. There are therefore numerous incentives for putting fish health and fish welfare at the top of the agenda for fish-farming operations. In an effort to ensure that we continuously fulfil these obligations, the Group has chosen to invest substantial resources in preventive measures for fish health, and this is now a major part of the production strategy for the entire Group.

In a cage with fish, there will be  at least 97.5% water and at most 2.5% fish

Main goal density: Less than 25 kg/m3

We care about our fish and accept our ethical responsibility that comes with animal farming. The Group's goal is qualitative and requires continuous monitoring and  targeted efforts throughout our farming value chain.