Late fall early winter recruitment of Calanus finmarchicus on Georges Bank

The development of Calanus finmarchicus in the Gulf of Maine (GOM), USA, and on Georges Bank (GB) was investigated during late fall, 1994, and winter, 1995, as part of the US-GLOBEC Georges Bank program. During November almost all of the C. finmarchicus population in both regions was present as C5(r) with a small proportion of C4 and females. There were very few animals on GB. In the southern GOM about a third of the C. finmarchicus population was in the upper 80 m and actively feeding; the remainder were below 120 m. On GB the C. finmarchicus population was also feeding; gut pigment content in both areas was between 3 and 13 ng copepod(-1). About one third of the adult females on GB were reproductively active while none in the GOM were reproductively active. By January C. finmarchicus C6 females formed a large proportion of the older stage animals on the Bank and in surface waters of the southern GOM. These were actively feeding and reproducing with a large cohort of young nauplii of C. finmarchicus present in the southern GOM and smaller numbers on the northeast peak of the Bank. There were very few C. finmarchicus nauplii on the crest of the Bank or on the southern flank. Based on abundances and stage composition, it appeared that spawning began in late December and that repopulation of the Bank took place in the region of the NE peak, with nauplii and reproductively active females being transported onto this region of the Bank from the GOM.