FEEDING, ICHTHYOPHONUS SP INFECTION, DISTRIBUTION AND GROWTH HISTORY OF NORWEGIAN SPRING-SPAWNING HERRING IN SUMMER

After its collapse in the late 1960s, 1991 was the first year of syste matic herring investigations after the Norwegian Sea stock returned to the traditional summer-feeding areas. Of 11 prey groups three dominat ed the diet; Calanus finmarchicus, Parathemisto spp. and Sebastes spp. There was a high prevalence of Ichthyophonus sp. at stations in the c entral and western parts of the Norwegian Sea where the cpue was low. This suggests that infected individuals were unable to return from the feeding to the wintering area of the Norwegian fjords. Highest cpue w ere recorded between 68-73 degrees N and 5-15 degrees E. Age groups 2, 3 and 8 were most frequently caught and age group 8 (the 1983 year cl ass) dominated the samples. Herring occurred in dense concentrations w here C. finmarchicus dominated diet. 0-group fish dominated diet at st ations along the coast from 66-73 degrees N and out to c. 300 km off t he coast. Mature herring overlapped in distribution with 0-group fish and Sebastes spp. contributed largely to herring diet in this area. Th e first rich year-class after the collapse, the 1983 year class, had a faster growth than rich year classes from past herring periods, but s lower than poor ones. (C) 1997 Tile Fisheries Society of the British I sles.