Salmon lice is the most common parasite when it comes to farmed salmon. It attaches to the skin of the fish, so is not found in the fish fillets we eat. Salmon lice eat mucus membrane, skin and blood and can cause large open wounds in the fish skin. An excess number of lice on a fish can cause wounds, infections and, in the worst case, can kill the fish. A number of treatments used to combat salmon lice can be stressful and harmful for the salmon.
Having a large number of salmon in one cage can provide optimal conditions for salmon lice, and the growth of the aquaculture industry has resulted in an increase in the number of salmon lice. Having a lot of lice in the sea is not only problematic for farmed fish, but also for wild salmon and trout, as the lice larvae swim with the current and disperse freely in the open water masses.
The Norwegian government has introduced a traffic light system for the aquaculture industry in Norway. Different areas are allocated a red, amber or green light depending on the impact salmon lice have on wild salmon in the area. The colour of the traffic light determines whether the fish farmers in the area are permitted to increase their production of salmon (green light), or whether production has to remain unchanged (amber light) or reduced (red light).
The websites of the Norwegian Institute of Marine Research and the Norwegian Veterinary Institute provide a good amount of information on salmon lice.

When farmed salmon escape from fish farms, they have a genetic impact on wild salmon.
When farmed salmon mate with wild salmon, the young fish are not as able to survive in nature. The wild salmon return to the river where they were born to spawn, and the salmon stocks adapt to the natural conditions in the watercourse to which they belong via a process of natural selection. Farmed salmon are bred with properties that are suitable for farming, but not as suitable for survival in a river.
The growth in the aquaculture industry has resulted in an increase in the numbers of salmon lice, also a problem for wild salmon and trout. In order to protect the wild salmon, the authorities have introduced a traffic light system for Norwegian fish farms. The numbers of lice in the fjords determines whether salmon production in the area can be increased, or has to be reduced to minimise the impact of salmon lice. Read more about this under salmon lice.

The salmon is perhaps our most important farmed animal. Around 400 million salmon are farmed in cages along the coast of Norway. Cleaner fish are also added to the salmon cages, and their function is to eat salmon lice. The cleaner fish have an important job to do in eating the salmon lice, but they have a high rate of mortality. The salmon themselves also have a higher mortality rate than is common for animal farming on land. The Norwegian Act concerning the welfare of animals states that “The habitat of animals shall promote good health and contribute to safety and well-being”.
Farmed salmon and cleaner fish are covered by the Act. Read more in the Fish Health Report published by the Norwegian Veterinary Institute as an annual status report on the health and welfare of fish.

Animals that live close together are exposed to infection. Viruses, bacteria and parasites can make farmed fish sick. Pathogens in the sea water are organisms that can cause disease and disperse with the sea currents. Infection zones between different fish farms have been enforced to prevent the dispersal of any outbreak of infection.
Farmed salmon are vaccinated against many of the diseases that can be caused by bacteria. As a result, the use of antibiotics in fish farming is now very low.
You can read more about the status of the health and welfare of farmed fish in the annual Fish Health Report published by the Norwegian Veterinary Institute.

Farming salmon in cages results in the discharge of organic material to the environment from feed residue and fish faeces. Excessive volumes of organic material can have a negative impact on the marine environment. The aquaculture industry must carry out environmental surveys of the seabed under fish farms. In 2019, 640 environmental surveys were performed. Of these, 58% achieved a “very good environmental condition” result, while 2% were classified as “very poor environmental condition”.
The Norwegian Institute of Marine Research publishes an annual Risk Report for Norwegian fish farming, in which researchers evaluate environmental impact and fish welfare. The environmental impact of organic discharges from Norwegian fish farming is assessed as low in the risk report published by the Institute.

Salmon feed is increasingly plant-based. Traditionally, salmon and trout feed was exclusively made from marine sources, but salmon feed today is made from approx. 70% vegetable ingredients. The reduction in the amount of marine raw materials in feed helps combat over-fishing, but the use of vegetable feed requires use of major agricultural areas.
There is a lot of ongoing research into new ingredients for feed, in order to find sustainable solutions for the production of feed. Can salmon eat insects? Or what about seaweed and mussels?

The aquaculture industry involves food production in coastal waters belonging to the public. Norway has one of the longest coastlines in the world, but the sea areas available for aquaculture are still limited. It is necessary to establish infection zones around the farms, and the fish farmers need localities where there is plenty of water flow and that are sheltered from the weather and wind. Aquaculture may also conflict with other interests along the coast, such as outdoor pursuits, fishing, nature conservation and landscape values.
What does society gain in return for the aquaculture industry occupying public areas? The industry directly employs around 8,500 persons. It also generates approx. 30,000 full-time equivalent jobs in other industries. The Norwegian government has established an Aquaculture Fund to ensure that the municipalities that house the aquaculture industry also receive a share of the earnings generated by the industry’s growth. In 2020, the Aquaculture Fund paid NOK 2.2 billion, divided among 150 coastal municipalities.

The UN has established 17 Sustainable Development Goals for the global community leading up to 2030. At Storeblå, we highlight several of these Goals as particularly relevant for aquaculture. You can read more about all the 17 Sustainable Development Goals on the UN’s website.

Goal no. 2: Zero Hunger
Only 2% of the energy provided by the food we eat comes from the sea. Can aquaculture help provide more food for the world?

Goal no. 13: Climate Action
All food production leaves a carbon footprint, including food from the sea. Can aquaculture grow as an industry without increasing its emissions?

Goal no. 14: Life Below Water
Aquaculture is the fastest growing food industry worldwide. Can we produce food in the sea without harming the environment?
We need to achieve sustainable utilisation of marine resources so that future generations have the same opportunities as us to harvest food from the sea.

Read more about how Norwegian aquaculture affects the environment, society and economics at barentswatch.no.
You can also read the Norwegian Institute of Marine Research’s annual risk assessment of Norwegian fish farming.