Undersøkelser av akkar, Todarodes sagittatus (Lamarck), i norske kyst-og bankfarvann i september-desember 1984, april og august-september 1985, ved Shetland i juli 1984, og ved Færøyene i august 1985

Abstract

During the second half of 1984, T. sagittatus invaded the Norwegian coastal waters, but less abundant than in 1983. During the spring and summer 1985, squid was present in small numbers. In the autumn of 1985, T. sagittatus again frequented Norwegian waters, more abundantly than in the previous year. Materials for investigation were obtained from research cruises near Shetland in July 1984, from Norwegian coastal banks in April and August-September 1985 and, through the courtecy of the Faroese Institute of Fisheries Investigations, from the Faroes in August 1985. During September-December 1984, samples of squid were also obtained from commercial catches along the coast of Norway. From July to December 1984 the mean dorsal mantle length (DML) of the females increased from near 21 cm to about 33 cm. In April 1985, females measured 33-43 cm. In August 1985, the squid at the Faroes measured 24 cm in average, similar to those from the Norwegian coastal banks in August- September. In the latter area, a few larger females, ML 42-47 cm, were also present. The stomach contents were mostly dominated by small fish, mainly blue whiting and pearlside. At the Faroes, a decapod, not identified, was also frequent. In stomach contents of squid from commercial catches at the coast of Norway, squid remains were common. The liver percentages were very variable, with mean values mostly below 10%. Age determinations, based on counts of primary growth rings in the statoliths, confirmed observations from earlier years , with mean ages of 9-10 months . This also applies to squid caught in April. Squid, caught during July-October 1984, were supposed to be hatched in November 1983-January 1984, those caught in December, in January-March 1984; those taken in April 1985 were hatched in June 1984. Squid, caught in August-September 1985, were mainly hatched in November-December 1984. In 1984 the commercial fishery yielded about 8 000 tons, in 1985 close to 14 000 tons.