Sildeundersøkelsene i Nord-Norge 1962/1963

Abstract

A progress report of the herring investigations in Northern Noway from September 1962 to May 1963 is presented. l. In autumn 1962 only small concentrations of the 0-group were recorded in the open sea off Northern Norway (the area around Bear Island and in the Barents Sea). Even though the herring were more abundant along the coast than in the open sea the 1962 year-class as a whole is expected to be rather poor compared to the 1959 and 1960 year classes. During the period of investigation fat herring of the 1959, 1960 and 1961 year-classes were observed several places on the banks along the coast. The best concentrations were recorded in the Lofoten-Vesterålen area, off the coast of West-Finnmark and on the Skolpenbank. 2. The migration from the coastal waters into the fjords took place in September-October and the herring consisted almost entirely of the 0 and 1-groups. In some areas, however, the herring were mixed up with the 1960 and 1959 year-classes. During the immigration the herring moved from warmer to colder water, the temperature decreasing inwards 1-1.5°C in the surface layer. During the winter 1962/63 no distinct warm intermediate water-layer existed in Ullsfjord (Troms). The water was warmest near the bottom where also the herring were observed. The herring left the fjord from March to May. In Porsangerfjord (West-Finnmark) the herring remained in the coldest water throughout the winter and no emigration had taken place when the investigations were finished. 3. In five localities a total of 6400 herring were tagged with intemal steel tags (Table 1). No recaptures of the fat herring tagged off Torsvåg have been reported. The recaptures of the 0-group (mussa) were all taken near the tagging localities, the fishing mortality of the tagged herring being 12.1 % in Vesterålen, 21.0 % in Malangen and 23.9 % in Ullsfjord-Lyngenfjord. If the Lyngenfjord is excluded from the fishing area the mortality is estimated to 26.5 %.