The Davis Strait - DCE - Nationalt Center for Miljø og Energi

September when they have reached a length of about 6-8 cm. Store Hellefiske
Bank, Disko Bay and Disko Bank west of Disko Island are well documented
settling and nursery areas (Smidt 1969, Stenberg 2007) but larvae are
also brought into the Baffin Bay by the West Greenland Current and to the
East Coast of Canada (Bowering & Chumakov 1989) by a branch of the West
Greenland Current that flexes towards west at the sill between Greenland
and Baffin Island. This drift pattern has been strongly supported by observations
of egg and larvae and by models simulating the drift of Greenland halibut
eggs and larvae (Stenberg 2007). Elsewhere in the Northwest Atlantic
spawning has only been observed sporadically in the Baffin Bay and inshore
in the Northwest Greenland fjords (Simonsen & Gundersen 2005) and along
the east coast of Canada (Bowering & Brodie 1995). The Greenland halibut
populations in the Davis Strait, Baffin Bay, inshore areas in Northwest
Greenland and the east coast of Canada area are therefore believed to be recruited
from the spawning stock in the Davis Strait.
Migration: Tagging studies from eastern Canada (Bowering 1984) and West
Greenland (Boje 2002) and recent unpublished data from Greenland Institute
of Natural Resources together with studies based on survey data (Jørgensen
1997) show that Greenland halibut gradually migrates towards greater
depth and towards the presumed spawning area as they grow, reaching the
spawning area as adults. One- and to some extend two-year-old fish feed on
zooplankton in the water column while older fish feed on shrimps, fish and
squids that are taken either at the sea bottom or during irregular feeding migrations
into the water column (Jorgensen 1997).
Sensitivity and impacts of oil spill: The assessment area includes the main
spawning ground for Greenland halibut in the Northwest Atlantic and recruitment
to important fishing grounds in the Davis Strait, Baffin Bay, eastern
Canada and inshore waters in Northwest Greenland and Canada is dependent
on recruitment from this area. Eggs and larvae that drift slowly
though the assessment area (Simonsen et al. 2006, Stenberg 2007) at depths
of 13-40 m are very vulnerable to oil if exposed to a large subsurface plume.
In such a case, effects on recruitment to the fishery should be expected.
Tainting by oil residues in fish meat is a severe problem related to oil spills.
Fish exposed even to very low concentrations of oil in the water, in their
food or in the sediment where they live may be tainted, leaving them useless
for human consumption (GESAMP 1993). In the case of oil spills, it will be
necessary to suspend fishery activities in the affected areas, mainly to avoid
the risk of marketing fish that are contaminated or even just tainted by oil
(Rice et al. 1996). This may apply to the Greenland halibut fisheries within
the assessment area. Large oil spills may cause heavy economic losses due to
problems arising in the marketing of the products. Strict regulation and control
of the fisheries in contaminated areas are necessary to ensure the quality
of the fish available on the market.
Atlantic cod, Gadus morhua
Biology: The Atlantic cod is an epibenthic-pelagic species (Coad & Reist 2004)
and is distributed in a variety of habitats from the shoreline to the continental
shelf. The cod is an omnivorous species eating anything from invertebrates
to fish, including younger members of its own species. Atlantic cod
spawns once a year in batches (Murua & Saborido-Rey 2003). Old and large
female cod produce more eggs of better quality per female compared to
young and small female cod. Eggs from old and large females also have a
higher probability of surviving (Kjørsvik 1994). In Greenland Atlantic cod
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