MIGRATION BEHAVIOR OF NORWEGIAN SPRING SPAWNING HERRING WHEN ENTERINGTHE COLD-FRONT IN THE NORWEGIAN SEA

The distribution of Norwegian spring spawning herring when migrating t o the feeding areas in the Norwegian Sea in spring was mapped by acous tic surveys in April 1995 and 1996. The schooling behaviour of the her ring was recorded by a high-resolution sonar, and the swimming speed a nd swimming direction were quantified by tracking individual schools f or up to one hour. In early April the herring migrated in the Norwegia n Sea from the continental shelf off Norway, between 66 degrees and 68 degrees N, and westward to 2 degrees W. When reaching the cold-water front, at about 0 degrees, the herring turned southward along the fron t. During daytime the herring migrated in large schools at 300-400 m d epth; at night they rose to surface and either dispersed or maintained schooling.