In recent years, blue whiting, a species in the codfish family, has become increasingly important in the production of salmon feed in step with declines in other fish stocks, such as capelin, herring and sandeel.
Problems for salmon
Fiskeriforskning's studies show that too large amounts of fishmeal based on sandeel cause a number of problems for salmon, such as poorer growth and feed utilisation.
Even though the meal contains a lot of phosphorus, which is necessary to convert food substances in the body and build up bones, the fish cannot absorb what it needs to develop normally.
Critical phase
The tests have been done on salmon smolt weighing around 120 grams. In the smolt phase, the salmon undergoes great changes because it has to adapt from a life in fresh water to a life in the sea. This is a critical phase in the development of the skeleton, and it is shown that too little phosphorus in the feed at this stage can cause deformities in the vertebral column of salmon.
Tests with extra supplements of phosphorus in feed based on sandeel showed that the salmon developed normally.
"The results show that we should consider adding phosphorus to the feed, depending on the types and quantities of raw materials used", says Senior Scientist Sissel Albrektsen.
The project is financed by FHL Fiskemel, Norges sildesalgslag and the Research Council of Norway.
