Spatial and temporal distribution of post-smolts of Atlantic salmon (Salmosalar L.) in the Norwegian Sea and adjacent areas

Knowledge of the migrations and geographic distribution of post-smelts of A tlantic salmon (Salmo salar L.) in oceanic waters is sparse. Surface trawl surveys were carried out by the Institute of Marine Research, Bergen, Norwa y, in the Norwegian Sea and adjacent areas in 1990-1998. Sampling was carir ed out south of 62 degreesN in May-June, in the Norwegian Sea north of 62 d egreesN in July-August and in the Barents Sea in August-September. In a tot al of 955 surface trawl hauls, 535 post-smelts were caught. The highest inc idences of post-smelts were in the slope current west of the British Isles, where the highest catch per unit of effort (c.p.u.e.) value was recorded b etween northern Scotland and the Faroes in June 1997. The lowest c.p.u.e. w as observed in August/September 1998 in the Barents Sea, where no post-smol ts were caught. The post-smelts appear to follow the main surface currents northwards into the Norwegian Sea where they spread in a fan-like distribut ion over an area covering most of the international waters between the excl usive economic zone (EEZ) of Norway, the Faroes and Iceland up to about 73- 75 degreesN. This pattern appeared to be stable between these years with th e exception of 1997, when almost no post-smelts were caught in the northern most areas, although catches in the south were similar to or higher than in the previous years. The geographical distribution of post-smelts of Atlant ic salmon is associated with the warmer, saline Atlantic water. (C) 2000 In ternational Council for the Exploration of the Sea.