Start-feeding and on-growing of wolffish (Anarhichas lupus) in the laboratory

Three groups of newly hatched wolffish larvae (one group in the Faeroe Islands and two groups in Norway) were start-fed on commercial dry pellets. Survival rates were between 10.5 and 53.7% during the first 108 days after hatching. The specific growth rate varied between 2.00 and 3.34%/day in the same period. A high mortality was observed between 20 and 40 days after hatching. A maximum specific growth rate (3.0–3.6) was observed 100–150 days after hatching, followed by a decrease to 0.4 and 0.8 at the end of the experiment. High mortality was observed in one of the groups during the juvenile stage, caused by heavy infection by the ectoparasite Trichodina sp. The behaviour of both larvae and juveniles was studied. The larvae spent most time in midwater while juveniles were most active around feeding time and spend most of the day lying on the bottom of the tanks. Cannibalism was observed occasionally and only among larval fishes. No cannibalism was observed in the Faeroe Island fish which were continually fed at 10 min intervals throughout 24 h.