Early weaning of Atlantic halibut (Hippoglossus hippoglossus) larvae

Abstract

Atlantic halibut is a cold-water pleuronectiform of the North Atlantic with a high market price and a small wild stock, therefore it has a large potential in farming. However, the halibut is difficult to grow and although work aimed at domestication has been going on since the late 1980ies, there are still only a few commercial farms. The purpose of the present study was to establish a time-point for early weaning of Atlantic halibut larvae, using feed intake as a proxy. First, three commercial diets (Otohime, Gemma Micro and AgloNorse) were compared at 28 days post first-feeding (dpff), with respect to feed intake during 5 days after weaning, using four replicate tanks. The number of larvae per tank out of 28 which had filled guts on the different diets, was 26.7 ± 2.3 (Otohime), 12.0 ± 0.6 (Gemma Micro) and 14.7 ± 1.2 (AgloNorse), respectively. Otohime was chosen for an experiment where feed intake for 5 days after weaning was monitored, starting at 15, 22 and 28 dpff. There was a gradual increase in success with larval age. At 15 dpff the larvae did not eat and there was an almost 100% mortality, at 22 dpff, 12 ± 1 out of 17 larvae survived and 7.3 ± 1.5 had filled guts. At 28 dpff, 14 ± 3 out of 17 larvae survived and all of them had filled guts. The development seems to correlate with the development of larval type digestion. Based on feed intake, successful weaning can be achieved at 28 dpff, however, further studies are needed to determine growth, survival and juvenile quality of Atlantic halibut larvae that have been weaned early on formulated diets.