Development of a non-contact method for the removal of ectoparasites from salmon in aquaculture

Salmon is one of the most popular food fish in Germany. To meet the constant demand, salmon is reared in large aquaculture facilities at sea. The largest producer is Norway, but aquaculture facilities for salmon can also be found in Scotland, Ireland and Chile.

A major problem in salmon farming is the salmon lice (Lepeophtheirus salmonis (Krøyer, 1837)), a parasite that spreads rapidly and infests the fish in the densely populated farms. At high infection rates, animal welfare and animal health of the fish are severely compromised which can lead to a financial loss of several 100 million euro per year.

In addition to the economic damage, the net cages represent a source of infection from which the parasite can spread to wild stocks. Wild salmon near the salmon farms are infested by the lice and thus weakened. The small crustaceans feed on tissue, mucus and blood of the fish which causes wounds that become infected and thus lead to the death of the fish.

Farmers treat the infestation with salmon lice elaborately and the methods used so far result in high stress for the fish. In addition to the thermal treatment, in which the salmon are pumped out of the net cages and into approx. 30°C warm water, chemicals are often used to kill the lice. However, if the wrong dosage is used, the treatment effect can be weakened and there is the risk that the parasites become resistant against the active ingredient.

Therefore, together with the partners Micor GmbH, glammeier+john, Purima GmbH and TTZ-Bremerhave, a new treatment method for controlling salmon lice will be developed. By combining infrared light with ultrasound in one treatment section, the parasites are to be gently and contactlessly separated from the host and then filtered out of the water.