Patterns in the variations of copepod spring and summer abundance in the northeastern Norwegian Sea and the Barents Sea in cold and warm years duringthe 1980s and 1990s

Abundance estimates of copepodite and adult Calanus finmarchicus, Pseudocal anus spp., Oithona atlantica, O. similis, and Oncea borealis have been obta ined lu icr a year by PINRO for the northeastern Norwegian Sea and the Bare nts Sea for the: 30-year period 1964-1994. The data cover the upper 50 m of the water column juring spring or early summer (i.e. April-July) along fiv e inshore-offshore transects at 67 degrees 30'N, 71 degrees 10'N, 72 degree s 50'N, from North Cape to Bear Island, and at Kola (33 degrees 30'E). Alon g the Kola transect, data are also available for three depth strata coverin g the entire water column. For this study, information is extracted from th ese data sets for eight years, three cold (1979, 1980, and 1981) and severa l intermediate and warm years (1983, 1984, 1989, 1991, 1992). Spatial distr ibution patterns and the demography of C. finmarchicus, the target species, are described for the study area, In the time window studied, changes in a bundance of C. finmarchicus between years appear to be a large-scale phenom enon throughout the entire study area. Unlike the results of previous studi es, no clear interannual relationship between water temperature and copepod abundance was found. A correspondence analysis including the smaller copep od forms, as well as temperature and salinity data, revealed a consistent r egional difference in the demography of Calanus, with Stages from CIV to ad ult more common in the southwest of the study area. Other copepod taxa domi nated over the shelf in the northeast of the study area, perhaps related to differences in the physical environment and in habitat preference. (C) 200 0 International Council for the Exploration of the Sea.