One of the challenges the aquaculture sector faces is access to sustainable , nutritional and cost-effective feed ingredients. The zooplankton Calanus finmarchicus (C.finmarchicus), widely available in subarctic waters of the North Atlantic , has a beneficial chemical composition for use in fish feed. Only recently a commercial quota on C. finmarchicus has been set, opening possibilities to harvest and utilize this nearly untapped resource, with an estimated new production per year of 290 million tonnes in the Norwegian Sea alone. Calanus is a natural feed for fish– and it has a composition that makes it relevant both for feed and human consumption. C. finmarchicus biomass consists of astaxanthin rich lipids – with high n-3 PUFA content, proteins – with a well balanced amino acids composition, and free amino acids - that are known to induce strong feeding responses . Currently oil is sold as high value marine oil for human consumption , while market for the protein fraction is at an early stage commercially.
In the CalaFeed project focus has been on increased knowledge to enhance the potential of using C. finmarchicus as a feed ingredient for aquaculture. Researchers have studied how to treat the catch after harvesting to keep the nutrients up to finished products. In addition, different protein ingredients ( fish protein hydrolysate (FPH) and fish protein concentrate (FPC) are tested in feeding trials with salmon.
The high innate enzymatic activity is a challenge for preserving lipids and proteins . Today, C.finmarchicus, is frozen on board, but freezing is an energy demanding process and not so relevant for feed ingredients- nor for preserving large biomasses on-board. In addition, even during frozen storage enzymatic degradation of lipids takes place. Ensiling technologies with the reduction of pH is a commonly used preservation method for feed raw materials. Both enzymatic degradation and oxidation may be influenced by storage pH. In the current study – the effect of different pH´s were investigated- to evaluate how pH can be used to control the unwanted biochemical changes during the silage process – and if ensilage can be an energy -efficient alternative to freezing the biomass on-board. Calanus has also high content of small molecules, such as free amino acids, that may act as attractants to fish . The current study focuses on finding suitable on-board handling – and processing methods for producing nutritional ingredients from C.finmarchicus . The results from feeding trials show that both C alanus FPH and FPC stimulated feed intake, growth, and health of salmon in the first challenging period after seawater transfer. To our knowledge, this is the first study that evaluates if ensiling technologies can be a relevant method for preserving C.finmarchicus biomass for feed purposes.