A possible connection between hydrography and the distribution of Calanus finmarchicus on the Norwegian midshelf in 1997

A majorCalanus finmarchicusoverwintering population inside a deep fjord in northern Norway: implications for cod larvae recruitment success

“…This part of the Norwegian shelf is the major spawning ground of Arcto-Norwegian cod, and the interaction between the circulation system and copepod phenology may explain why this region has successful cod spawning ( Sundby and Nakken, 2008 ). The earlier development of the nauplii cohort originating from overwintering C. finmarchicus inside Vestfjorden compared with cohorts originating from oceanic areas further off-shelf ( Pedersen et al ., 2000 ) means that cod larvae developing on the shelf around the Lofoten grow in an environment with high abundances of their principal food for an extended period of time. Recent research on the match–mismatch hypothesis indicates that the duration of overlap between favorable prey concentrations and the predators might be more relevant for recruitment success and year-class strength than the overlap of peak abundances of prey and predator ( Durant et al ., 2005 ; Kristiansen et al ., 2011 ).…”

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

“…This, of course, may be linked to differences in the environment between stations in the open ocean in the west and stations over the shelf, i.e. two regimes each with its own particular timing of copepod recruitment and production (Pedersen et al, 2000). Along the Kola meridian (transect E) there is a tendency for abundance to decrease towards the south (for 1979, 1980, 1981, 1989), a trend that may be rooted in differences in faunal and seasonal succession between Arctic and Atlantic water masses.…”

Habitat selection of overwintering Calanus finmarchicus in the NE Norwegian Sea and shelf waters off Northern Norway in 2000–02

“…Recent studies have shown that C. finmarchicus is an oceanic species, dependent on the colder deep-water for overwintering and on the basin scale circulation to obtain spatial closure of its lifecycle (Backhaus et al, 1994;Bryant et al, 1998;Heath and Jonasdottir, 1999;Heath et al, 2000). The continental shelf areas, being too shallow to provide an overwintering habitat, are nonetheless invaded by this species in spring and summer (Gallego et al, 1999;Gaard, 2000;Gislason et al, 2000;Pedersen et al, 2000), when it constitutes an important prey item for larval and planktivorous fish (Skjoldal and Rey, 1989;Gjøsaeter, 1998;Gjøsaeter et al, 2002). The spring invasion of the North Norwegian shelf and the Barents Sea is partly the result of the northward advection of C. finmarchicus from the overwintering sites in the southern part of the Norwegian Sea, but the present study demonstrates that there are also important overwintering sites in the Lofoten Basin and along the continental slope off North Norway.…”