Evaluation of Calanus copepod and Euphausia krill meal and oil as dietary protein and lipid supplements for juvenile Atlantic halibut (Hippoglossus hippoglossus L.)

The Calanus copepod (Calanus finmarchicus) and Antarctic krill (Euphausia superba) are potential protein and lipid sources for marine fish feeds; however, their nutritional value for Atlantic halibut has not been investigated. Three experiments were conducted to determine the suitability of Euphausia krill and Calanus copepod meals and oils as a protein and lipid source for halibut. Weight gain was significantly higher (P<0.05) when 12, 20 and 30% dietary protein was replaced by Calanus in a plant-based diet. Protein and energy digestibility of Calanus meals (90-99%) significantly decreased with increased heat processing. Krill meal had higher lipid digestibility (99%) than Calanus meals (90-95%). Krill oil contained lower amounts of EPA (6%) and DHA (2%) than Calanus oil (10% EPA; 11% DHA) and was more digestible (>90%), likely due to the wax esters in Calanus lipid. It appears that krill and Calanus meal and oil can be utilized in Atlantic halibut diet.