Seasonal abundance and development of Calanus finmarchicus in relation to phytoplankton and hydrography on the Faroe Shelf

Calanus finmarchicus is almost absent from the Faroe Shelf during winter an d is advected into the shelf ecosystem during spring and summer. The specie s starts to spawn prior to the onset of the spring bloom. During the pre-bl oom phase, reproduction is usually highest over the western and northern pa rt of the shelf and the nauplii and copepodites are dispersed by the anticy clonic current throughout the shelf area. Gonad maturity evaluation reveale d that females over the central shelf during 1997 were immature until early April, after which the proportion of mature females gradually increased an d peaked at about 80-90% mature in May-June and August. Pre-bloom reproduct ion on the central shelf in 1997 Mas low and the recruits present then were most likely advected from the northern or western shelf. Two main periods with peaks of abundance were observed on the central shelf during 1997, the largest in May-June (similar to 250 individuals m(-3)) and another in late August (similar to 100 individuals m(-3)). Off the shelf, the abundance of C. finmarchicus in most years was significantly higher than on the shelf, and the proportional mix of stages differed. (C) 2000 International Council fur the Exploration of the Sea.