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

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