Stock size fluctuations and rate of exploitation of the norwegian spring spawning herring, 1950-1974

Abstract

Stock size fluctuations and rate of exploitation of the Norwegian spring spawning herring, 1950-1974. FiskDir. Skr. Ser. HavUnders., 16: 315-337. The collapse of the Norwegian spring spawning herring stock is described, followed by a discussion of the causes. Stock size and fishing mortality were calculated from virtual population analysis for the years 1950-1974. The analysis showed that the young herring fishery had a serious effect on the recruitment to the adult stock during the whole period. The 1961 year class was the last one which survived the small- and fat-herring fisheries in any quantity. The fishing mortalities on the adult stock were at a low or moderate level until 1964. Thereafter a rapid increase in the fishing mortalities took place, primarily as a result of the escalation in the summer and autumn fisheries off Iceland. The result of the investigation leaves no doubt that the fishing pressure was the primary factor for the collapse of this herring stock.