What salmon eat. Composition of feed

Salmon are fed dry pellets. They contain around 70 percent vegetable ingredients and 30 percent marine raw materials like fishmeal and fish oil.

Fish oil is fat from fish parts or industrial fish (i.e. fish that is not intended for human consumption). Fish oil has a high content of the omega-3 fatty acids EPA and DHA. From one kilogram of industrial fish, around 80 grams of fish oil can be produced.

Vegetable ingredients in the fish feed are derived from plants like soy, sunflowers, rapeseed, corn, broad beans and wheat. The vegetable products are a source of protein, carbohydrates and fat. Some feed products contain 0.5 percent palm oil as a binding agent. 

Fishmeal is produced by fish heads and other parts that are not used for human consumption. Fishmeal contains proteins and minerals. From one kilogram of industrial fish, around 230 grams of dry fishmeal can be produced.

Fish protein concentrate is produced by scrapings from the consumer fishing industry.

The fish feed also contains vitamins, minerals, pigments and amino acids. The antioxidant astaxanthin is added to salmon feed to boost the fish's immune system and to protect their tissue. It is also a source of vitamin A. Astaxanthin is the substance that gives salmon its red color. Wild salmon get astaxanthin by eating crustaceans.

Does salmon feed contain toxins?

Norwegian fish does not contain high levels of heavy metals or contaminants. The research institute NIFES was commissioned by the Norwegian Food Safety Authority to investigate if Norwegian fish feed contains high levels of illegal substances. The report from 2015 concluded that the regulatory thresholds are rarely exceeded. The results showed that so-called complete feed and feed ingredients do not exceed the limits for heavy metals and organic pollutants. The exception is one complete feed, which contains residues of the pesticide hexachlorobenzene (HCB) over the limit. The limit for HCB is 10 micrograms per kilogram, and the complete feed was found to have 11 micrograms per kilogram. According to NIFES, the level is still so low that it does not pose a risk to food safety.

As fish feed increasingly consists of vegetable ingredients, NIFES has expanded the list of monitored pesticides. The samples from 2014 showed that the levels of pesticides are generally low.

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

Fishmeal and fish oil, the main ingredients in salmon feed, are classified as renewable resources. They are made from fish scrapings and fish that are not used for human consumption, and only species that are not exposed to overfishing are used.  Fish farming is a rapidly growing industry, and the aquaculture industry has a responsibility to ensure that the resources are used in a sustainable manner. Production of omega-3 supplements has increased the demand for marine products, but there are not enough marine raw materials to meet the growing demand.

Wild fish from regulated fisheries

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. From the southern hemisphere, mainly anchovies are used.

Replacing wild fish with vegetable ingredients

Despite the tremendous growth of Norwegian aquaculture, the industry has not increased the usage of wild fish. The reason is that fish feed manufacturers have partly replaced marine raw materials with 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. 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 is made up of sustainably produced vegetable ingredients like soy [insert internal link]. 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. According to studies from NIFES, it is possible to produce one kilogram of salmon with less than one kilogram of wild fish.

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.