Diet composition and intra-specific competition of young Greenland halibut around southern Greenland

This paper focuses on young Greenland halibut as a predator, aiming to investigate whether particular prey items dominated the stomach contents of particular length groups of the predators, and whether distribution between areas affected the diet composition. It also investigates possible cannibalistic behaviour and intra-specific competition. A total of 665 stomachs were sampled from Greenland halibut in the length range 15–65 cm; the majority in the length range 20–49 cm (91.4%). Of the stomachs collected 35.2% were empty. Main prey items in the stomachs were species of Crustacea and Teleostei. The occurrence of species of Teleostei was significantly higher in southeast than in southwest Greenland. Of the Teleostei, polar cod was the most abundant prey in stomachs collected in southeast Greenland and capelin in the southwest. Analyses of bycatch in the gillnets indicated that Greenland halibut preferred capelin when this prey was present. The occurrence of Crustacea was higher in the southwest than in the southeast, and main prey items were Natantia, Mysidacea, Amphipoda and Hyperiidae. Natantia seemed to be a more important prey for the largest length group of Greenland halibut analysed. The results from the stomach analyses indicate that cannibalism is a minor problem for Greenland halibut in these waters.