Predators of the squid Gonatus fabricii (Lichtenstein) in the Norwegian Sea

Gonatus fabricii is the most abundant squid of the Arctic and sub-Arctic waters of the North Atlantic and, during the summer months, young specimens can be found in the upper 60 m over large areas of the Norwegian Sea. In the summer of 1994, the biomass of young G. fabricii in this area was calculated to be at least 1.5 million tons. When the young squids reach a mantle length (h IL) of 50-60 mm, they disappear from the surface and can be found at depths greater than 400 m. The life span of both sexes probably does not exceed 2 years, and the largest specimen ever recorded was a female of 385 mm ML. The biomass production of this species represents a considerable food resource and their consumption by known predators such as sperm whales (Physeter macrocephalus), northern bottlenose whales (Hyperoodon ampullatus). long-finned pilot whales (Globicephala melaena) and hooded seals (Cystophora cristata) is discussed. It is concluded that the distribution of G. fabricii in the Norwegian Sea and its importance as food for sperm whales and northern bottlenose whales could, to a great extent, explain the presence of these species in the Norwegian Sea. (C) 2001 Elsevier Science B.V. All rights reserved.