The Northeast Greenland Shelf as a Potential Habitat for the Northeast Arctic Cod

Abstract

Observations (1978)(1979)(1980)(1981)(1982)(1983)(1984)(1985)(1986)(1987)(1988)(1989)(1990)(1991) of distributions of pelagic juvenile Northeast Arctic cod (Gadus morhua L.) show that up to 1/3 of the year class are dispersed off the continental shelf and into the deep Norwegian Sea while on the way from the spring-spawning areas along the Norwegian coast to the autumn-settlement areas in the Barents Sea. The fate of this variable fraction of pelagic juveniles off-shelf has been an open question ever since Johan Hjort's (1914) seminal work. We have examined both the mechanisms causing offspring off-shelf transport, and their subsequent destiny using an individual-based biophysical model applied to quantify growth and dispersal. Our results show, consistently with the observations, that total off-shelf transport is highly variable between years and may be up to 27.4%. Offspring from spawning grounds around Lofoten have a higher chance of being displaced off the shelf. The off-shelf transport is dominated by episodic events where frequencies and dates vary between years. Northeasterly wind conditions over a 3-7-day period prior to the off-shelf events are a good proxy for dispersal of offspring off the shelf. Offspring transported into the open ocean are on average carried along three following routes: back onto the adjacent eastern shelves and into the Barents Sea (36.9%), recirculating within the Lofoten Basin (60.7%), or drifting northwest to the northeast Greenland shelf (2.4%). For the latter fraction the transport may exceed 12% depending on year. Recent investigations have discovered distributions of young cod on the northeast Greenland shelf indicating that conditions may support survival for Northeast Arctic cod offspring.

Boreal marine fauna from the Barents Sea disperse to Arctic Northeast Greenland

“…DiscussionOur results show that the NE Greenland shelf is readily reached by cod, redfish and shrimp from the Barents Sea, probably advected across the Fram Strait by the Return Atlantic Current, supporting recent simulation studies[25][26][27] . Advection plays an important role in the northward transport of plankton in the Barents Sea, via the West Spitsbergen Current 18 and because up to 50% of this water is estimated to cross the Fram Strait[28][29][30] , the Return Atlantic Current provides a connection between the Barents Sea and the NE Greenland shelf ecosystems.…”

“…The NE Greenland shelf ecosystem is severely understudied and biodiversity baselines are fragmentary with no timeline 45 . It is therefore difficult to establish whether our findings reflect a recent shift driven by ocean warming or constitute a 27 demonstrates that between 2.4% and 12% of 0-group NEAC may be transported northwest along the proposed route ( Fig. 2a).…”

Seasonal Variation in Transport of Zooplankton Into the Arctic Basin Through the Atlantic Gateway, Fram Strait

“…Instead, zooplankton in the Uncertain Fate region might remain in recirculating AW, and could also be transported westward toward Greenland . Model simulations have shown that episodic events can transport cod larvae hatched outside the Norwegian coast toward Northeast Greenland, by taking the route with AW northward toward Svalbard and then westward across Fram Strait (Strand et al, 2017). The high abundances of Calanus sp.…”

Population variability under stressors is dependent on body mass growth and asymptotic body size

“…We illustrate how a model accounting for only two traits, the asymptotic size and growth rate, can be used to systematically quantify the sensitivity of fish stocks to environmental variability and fishing pressure. Frequently, larval survival and, accordingly, recruitment success is directly or indirectly influenced by the environment through factors such as food availability [33], drifting to favourable nursery habitats [34,35] and the effect of temperature on growth [36]. However, species with an asymptotic weight of around 140 g and a growth rate of > 3 g 0.25 year −1 showed less than 20% variability (log 10 = −0.7) in their recruitment in the present simulation.…”