Is salmon feed sustainable? Do farmed salmon eat wild fish?

To prevent overfishing, the fishmeal and fish oil from wild fish in fish feed have been partly replaced by vegetable ingredients.

Research has made it possible to reduce the amount of fishmeal and fish oil without compromising fish welfare or the quality of the salmon. Photo: Marius Fiskum/Norwegian Seafood Council

The aquaculture industry in Norway does not use fishmeal or fish oils made from fish on the World Conservation Union's (IUCN) list of endangered species.  To ensure that the wild fish come from regulated fisheries, fish feed companies monitor their suppliers through tracking documents and audits. The size of wild fish stocks may vary from year to year for many reasons – not just because of fishing. To prevent overfishing, it is crucial that the use of wild fish in aquaculture feed is regulated. In Norway, about 90 percent of the wild fish used in fishmeal and fish oil comes from regulated fisheries. The most commonly used species are herring, blue whiting, capelin, sprat and anchovy. Herring is only used when the catch is greater than the demand from the consumer market.


Replacing wild fish with vegetable ingredients

Despite the large growth in the aquaculture industry over the last 30 years, no more wild fish are used in the feed today than was the case in the past. This is because the feed companies have replaced some of the marine ingredients with plant ingredients.  Research has made it possible to reduce the amount of fishmeal and fish oil without compromising fish welfare or the quality of the salmon. In the 1990s, 90 percent of Norwegian salmon feed consisted of fishmeal and fish oil. Today, these two products constitute only around 30 percent of the feed, which is still enough to make sure the salmon have sufficient levels of the omega-3 fatty acids EPA and DHA. The rest of the feed consists of plant ingredients, such as soya, which are produced in accordance with sustainable principles. The salmon industry uses sensors and underwater cameras to reduce feed waste, i.e. feed that slips through the cage without being eaten. Today it is also easier to make use of scrapings and by-products from fish production.


Efficient feed utilization

Efficient feed utilization is crucial to ensure that the aquaculture industry is sustainable. The fish-in/fish-out ratio (FIFO) is a way to measure the extent to which farmed salmon utilize the feed. FIFO indicates how much wild fish, in the form of fishmeal and fish oil, is needed to produce one kilogram of farmed salmon. The FIFO ratio for fish oil dropped from 7.2 in 1990 to 1.7 in 2013, while the FIFO ratio for fishmeal went from 4.4 to 1.0 in the same period. The following factors affect the FIFO rate: how many kilograms of fishmeal and fish oil that can be derived from wild fish, how much of this that is used in the feed, and how oily the wild fish is.

Another way to measure feed utilization of farmed salmon is by checking how much of the nutrients in the feed is carried over to the salmon. According to surveys from 2012, 24 percent of the energy and 27 percent of the proteins transfer to the edible part of the salmon. Compared to chicken and pork, farmed salmon retains more energy, protein and phosphorus from the feed. This makes salmon the most resource-efficient meat produced in Norway.

If you want to know more about the production of feed for the aquaculture industry, you can visit the websites of the three main feed producers in Norway: Cargill, Skretting and BioMar.


Useful links:

The International Union for Conservation of Nature (IUCN) 

Norwegian Institute of Marine Research: Is it sustainable to use wild fish for aquaculture feed? (in Norwegian only) 

Utilisation of feed resources in production of Atlantic salmon in Norway (scientific article)

Norwegian Institute of Marine Research: Risk evaluation of Norwegian fish farming 2018 (in Norwegian only)