The global aquaculture sector is diverse with over 300 different species. Almost every country in the world is involved. Aquaculture is practised in three different environments. In 2016, 63 % was in freshwater, 28 % in marine waters and 9 % in brackish water (Coastal ponds) [1]. In 2016 approximately 70 % of the aquaculture production was fed species. This was fresh feeds like crop wastes, feed mixed and processed on the farm or commercially manufactured feed [2].

Carnivorous fish like salmon, shrimp and many other marine finfish relies mainly on plant materials like soya and wild-caught fish in the form of fish meal and fish oil in commercially manufactured feed. However, 80 % of the aquaculture production in 2014 consisted of omnivores, herbivores and filter feeders that consume little to no fish-based ingredients. Cereals, oil seeds and legumes often in the form of meals and oils is the main diet.

The fact that the supply of fish meal and oils from wild sources are limited represents a clear constraint on aquaculture production growth, particularly of farmed carnivorous fish like salmon. When the growth of species like salmon has increased during the last 30 years, the marine raw materials in the feed has been substituted with plant ingredients produced on land. Today the amount of fish meal and oil in the commercial salmon feed is down to less than 20 %.

Norwegian salmon production

Norway is today the largest producer of Atlantic salmon in the world. There is a national ambition to increase the salmon production to 5 million metric tons by 2050, which is 4-5 times the production today.  To be able to realize this growth potential, there are different environmental challenges that must be solved by the industry including parasites (sea lice), escapees and spills to the surrounding environment in the ocean.

However, the main challenge in the long term will be the availability of enough sustainable feed, with a carbon footprint as low as possible. Norwegian fish farmers, authorities and scientists are heavily involved in these questions. There are several ongoing initiatives to strengthen the feed supply. High attention is paid to the harvest of mesopelagic species, krill and zooplankton from the oceans. Conversion of plant materials to sugar and further to yeast, or the use of hydrocarbons (CCU, carbon capture and utilization) to bioproteins are alternatives.   

With an economic feed conversion rate of 1,2 (kg edible meat/kg of dry feed) an eventually increase in salmon production up to 5 million metric tons will require 6 million metric tons of dry feed. Although the production of salmon in the ocean is one of the most sustainable animal protein producers because (1) the availability of enough water, (2) the utilization of the water buoyancy, and (3) the low temperature of salmon compared to warm blooded animals like beef, the feed component is the most important factor to the carbon footprint of the total value chain for salmon production. Looking for sustainable feed raw materials is therefore on the strategic agenda for the salmon industry in Norway.

In this context, SINTEF Ocean [3] has made an evaluation of possible new feed resources that can contribute the ambitious growth expected for the Norwegian salmon industry. If this growth is not going to be covered by increasing the import of soy but substituted with domestic resources, 75 % of the proteins must be made available through other industrial processes than what are used today. The table below shows the different sources og of raw materials are evaluated:

Harvested	Cultivated
Marine: Pelagic fish Mesopelagic fish Red tide ("Raudåte") Arctic krill Other zooplankton 2 seaweeds Rest raw materials from the fishing industry Terrestrial: Soya Wood Grass Rest raw materials from warm blooded animals	Insects Polychaetes Gammarid shrimp Tunicates Mussels and shells Heterotrophic microorganisms (bioprotein) Microalgae (phototrophic) Macroalgae (phototrophic)

Table 1: Raw materials evaluated for salmon feed production

 

The raw materials were evaluated from three criteria:

• How much raw material is available today, or can be made available by 2050?
• Can the raw material contribute with at least 5 % OF the future need of protein and EPA/DHA?
• Can the raw material be made available through a sustainable process at an acceptable price, and can it be produced in Norway?

The evaluation shows that 7 out of the raw materials listed in the table above can be realistic contributors to the salmon feed demand by 2050. The table below shows the raw material that are already produced in industrial scale, or by further development and scaling up have such a potential in the future.

Industrial production today	Need development and/or scaling up
Pelagic fish Rest raw materials from the fishing industry Soy and other plants high in proteins	Mesopelagic fish Protein from grass Heterotrophic microorganisms Microalgae

Table 2: Raw materials for salmon feed production

Mesopelagic fish, a key factor for the Norwegian salmon industry

Detecting, harvesting and processing mesopelagic fish will be a key factor for further increase in aquaculture production of all carnivorous species dependent upon manufactured feed, including the salmon production in Norway. The nutritional composition of mesopelagic fish as raw material for feed production for salmon is favourable compared to plant materials.

The global industry, which today harvests and processes the pelagic species, possesses the technology and the experience to take part in the development needed. New feed raw materials are crucial for the aquaculture industry. Mesopelagic fish is today an underutilized renewable resource. These species must be utilized in a sustainable way to contribute and to strengthen the food value chain needed to feed a growing global population in the future.

The Norwegian salmon production has been stagnant for the last 8-10 years because of environmental challenges like parasites (sea-lice), discharge to water and escapees. These challenges must be solved before expansion can be obtained. However, the future expansion of the salmon industry is dependent on new sources of sustainable raw materials for feed production. The Norwegian government has therefore given research quota on 3,000 tons for developing the harvest of mesopelagic fish in Norwegians waters and for further processing to fish feed and other products. Together with stock estimates, this will be the basis for managing a commercial fishery in Norwegian waters in the future.  When the harvest can be documented to be sustainable, for example trough certification by MSC (Marine Stewardship Council), the consumers acceptance to mesopelagic fish as a feed ingredient in salmon production will be positive.  Harvesting mesopelagic fish is a possibility for further  expansion of the salmon production in Norway.

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