The formation and the disappearance of a stock unit of Norwegian herring, with a section on herring migrations east of Iceland by Jakob Jakobsson

Abstract

1. On February 2nd 1963 mature herring belonging to the Atlanto- Scandian herring were located off Finnmark between North Cape and Sørøy. 2. The herring arrived in the Røst Bank-Lofoten area, where it was recorded spawning late March 1963. 3. The migrations of the herring were seasonally followed by Norwegian research ships and hired ships through the years 1963-1966. The most likely migrations are demonstrated in Figs. 1-3. 4. The herring were recruited from the main stock of immature herring and consisted of the year-classes 1959, 1960 and 1961. 5. In 1963 only first time spawning herring occurred. In 1964 there were first and second time spawners. In 1965 there were also third time spawners and during the spawning season in 1966 there were first, second, third and fourth time spawners. 6. The herring had their own spawning, feeding and wintering areas separated far from the main stock of Norwegian winter herring. 7. In the autumn 1966 the stock unit disappeared. During the winter season 1967 and 1968 there was no spawning migration to the Lofoten-Røst Bank area.