Akkar (Todarodes sagittatus (Lamarc)) Innsig og forekomst ved norskekysten og tilstøtende havområder høsten 1979 - våren 1980

Abstract

During the second half of 1979 T. sagittatus invaded the eastern Norwegian Sea, the northern North Sea and the coastal and bank areas of the Faroes, Iceland and Norway. The squid stayed in parts of the areas at least to the end of April 1980. Materials for investigation were collected during research cruises off western and northern Norway in October, and in other areas from July 1979 to the middle of April 1980. Squid were also obtained from the commercial fishery and from the weather ship "Polarfront" at st. M in the Norwegian Sea. Data from the Faroes were kindly supplied by Mr. H.i Jakupsstovu. The mean mantle length increased from about 23 cm in August to 41-42 cm in February-April. The maximum individual length of 50 cm was observed in April. The mean monthly growth during different periods was calculated for the females. In August-September it was 5-7 cm, October-January 2,3 cm, January-February 1,5 cm, August-February 3,0 cm. Males were on average 2-3 cm shorter in mantle length than the females. In northern Norway the average mantle length was somewhat larger in October- November 1978 and 1979 than at the same time in 1977 and 1972. The mean total weight increased from about 280 g in August to 420-540 g in September and further to 1300 g in February. A female with mantle length of 50 cm and weighing 3130 g was taken in April. The length-weight curve was calculated from the relationship W=aLb . a=0.02, b-3.01. The liver weight varied considerably, both individually and between samples, but the mean weight was mostly below 10% of the total weight, except off northern Norway, Males were few, constituting 4-11% of the samples along the Norwegian coast and in the Norwegian Sea, but about 26% near the Hebrides in November. Nearly all were immature, but a few with developing gonads, weight 10-20 g, were found in January-February. Males, even small ones, are easily recognized in the catches by the poor quality of the skin which deteriorates and becomes chapped shortly after the catch. Food items in stomach contents were similar to those identified in earlier years. Fish dominated, herring, sprat, redfish, blue whiting and pearlside being most abundant. Squid ranged second, in Norwegian waters T. sagittatus, in the Norwegian Sea Gonatus -fabricii, and at the Hebrides, octopods. Various other organisms were identified, e.g. krill, deep-sea prawns and other shrimps, amphipods, polychaetes and chaetognaths. Age determinations from statoliths are in progress, but the interpretation is constantly difficult. It is assumed that the squid spawns at an age of 1-1 1/2 years. Observations with underwater TV indicated that the squid is very voracious, attacking various kinds of bait, including squid, and remaining on the bait for up to half an hour. Fishing technique is improving, and marketing for human consumption, both domestic and for export, is increasing.