Report on surveys of the distribution, abundance and migrations of the Norwegian spring-spawning herring, other pelagic fish and the environment of the Norwegian Sea and adjacent waters in late winter, spring and summer of 1999

Abstract

Introduction: The Norwegian spring-spawning herring reoccupied the Norwegian Sea as its main feeding area in the early 1990s, after nearly 25 years of absence. The herring stock is now a typical straddling and highly migratory stock, and its migration mute crosses the borders of several national EEZs (exclusive economic zones) and international waters. From 1994, an international fishery has taken place during summer in the area. The total catch of Norwegian spring spawning herring in the Norwegian Sea and along the Norwegian Coast in 1998 exceeded 1,2 million tonnes. Since 1995, the Faroes, Iceland, Norway, and Russia, and since 1997 also the EU, have coordinated their survey effort on this and other pelagic fish stocks in the Norwegian Sea. The co-ordination of the surveys has strongly enhanced the possibility to assess and describc the distribution of the pelagic resourccs, and their general biology and behaviour in relation to the physical and biological environment (Table 1) Based on an ICES recommendation in 1948, similar surveys were conducted under the auspices of ICES from 1950 to the late 70's. National surveys were continued after this time. At the 1996 Annual Science Conference, the Pelagic Committee recommended that the ICES cooperation should be reintroduced on the planing and conducting of future surveys on herring and the environment in the Norwegian Sea. For the survey efforts to be carried out in 1999, a planing meeting was held in Lysekil in August 1998 (Holst et al., 1998), and a series of 10 surveys to be carricd out by Faeroese, Icelandic, Norwegian, Russian, and EU-research vessels in spring and summer 1999 were coordinated (Table 1). The main objectives of the coordinated surveys were to map the distribution and migration of the herring and other pelagic fish, to assess their biomass, and to monitor environmental conditions of the Norwegian Sea and the quantity of available food in the sea for herring. The 1999 coordinated survey results were evaluated during a meeting in Hamburg in August 1999 (Table 1). The limited time available for the analysis allows only for a brief overview of the main findings of these surveys with respect to herring distribution and migration, environmental conditions (sea temperature, zooplankton biomass), herring abundance, and blue whiting distribution.