The squid Gonatus fabricii (Lichtenstein) : Investigations in the Norwegian Sea and western Barents Sea 1978-1981

Abstract

Gonatus fabricii is widely distributed in the arctic and subarctic waters of the north Atlantic Ocean. During summer and autumn juveniles are numerous in the surface layers of the Norwegian Sea. The adults live mainly below 300-500 m. G . fabricii is important as food for whales, seals and pelagic fishy and may be a potential fishery resource. Materials were collected with pelagic trawls during June-September 1978-1981, and from stomach contents of whales and seals caught at Jan Mayen and east of Iceland in earlier years. Dorsal mantle length (DML) in juveniles were 10-80 mm, in June-July with peaks at 20-24 mm and 55-59 mm, in September at 30-40 mm. The re1ation between DML and rostral length of the beak was calculated. Age and growth was estimated from counts of growth rings in the statoliths. In the juveniles there is a linear relation between DML and number of growth rings, with correlation coefficient r, varying from 0.44 to 0.89. The eggs are supposed to be hatched on the bottom at 300 m depth or more, with an incubation period of 70-100 days. A corresponding number of growth rings may be formed during this period. Hatching goes on during most of the year, with maximum in February - April. Growth of the juveniles is slow, about 0.2 mm a day. When the squid leave the surface layers, their growth rate increases considerably. The maximum age at a DML of 200-250 mm probably does not exceed one year. The food of juveniles consists of amphipods, copepods, chaetognaths and euphausiids. Larger animals also take young fish and squid. The distribution and spawning areas of G. fabricii are related to the current system of the Norwegian Sea.