Akkar (Todarodes sagittatus (Lamarck)). Norske undesøkelser i april-desember 1980.

Abstract

During the second half of 1980 T. sagittatus invaded the northeastern Norwegian Sea and adjacent coastal areas in great abundance. The invasion coincided with the occurrence of large quantities of salps. Squid still remained in coastal waters in January 1981. Materials for investigation were obtained from research cruises in northeast Atlantic waters in April - May, in the North Sea in July, and in the Norwegian Sea and coastal waters of Norway in August - December . Length and weight. The mean dorsal mantle length (DML) of squid hatched during the autumn of 1979 increased from 16-18 cm in April to 31-32 cm (males) and 35-38 cm (females) in December. A specimen of DML 59 cm and weight (W) of 5300 g was reported caught in October. The relation between weight and mantle length W = a(DML)b was calculated on material from 1979 - 1980. Males (DML 17-41 cm) : a = 0.0181, b = 3.0181, r2 = 0.9447. Females (DML 14.5-50 cm): a = 0.0180, b = 3.0170, r2 = 0.9419. Liver weight. On the Porcupine Bank and at st. M in the Norwegian Sea the liver averagely constituted about 7% of the total weight, in other areas 9-10%, with individual variations of 3.7 - 17.2%. Sex proportions. In fjords and coastal areas males constituted 0-10%, on the banks about 13%, in oceanic areas 22-28%. The low proportion of males in the fjords is ascribed to cannibalism. Maturation. In April - May, males with DML above 30 cm were maturing, most of them with spermatophores developed. In October - November a few large males had developing testes. During July - December all females taken were immature. In April - May about 50% of females with DML above 35 cm were maturing or mature, with nidamental glands 50-100 mm in length. One female with DML 44 cm had eggs (oocytes) in maturity stage 3. Total number in the ovisac was calculated to 84 500, considerably above earlier literature records. Stomach contents. As recorded earlier, fish were most common. Blue whiting, pearlside, Notoscopelus krøyeri, Notolepis rissoi krøyeri, redfish, herring or sprat and whiting were identified. Of squid, T. sagittatus, Gonatus fabricii and small octopods were found. Of other organisms krill and Hyperiids were most common. Pasiphaea sp., Pareuchaeta sp., Nereis sp., Eukrohnia sp. were also identified. Age. A report on daily rings in the statoliths has been published. The age readings revealed two main periods of hatching, September - November and April - June, but reproduction also occurs at other times of the year. Squid caught in October, are probably one year or less of age, but the specimen with DML 59 cm might be 11/2 - 2 years old. Fishery. In 1980 the fishery yielded 2 500 m. tons. The possible yield was estimated to 25-50 000 tons.