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

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depths between 100 and 800 m and at bottom water temperatures ranging
from about –1.0°C to about 4.5°C.
Movements: The Greenland coastal system consists of fjords and basins. Fjord
populations of snow crab in the benthic phase are partially or completely
isolated from one another and from offshore populations by sills
(Burmeister, unpubl. tagging data, Burmeister & Sainte-Marie 2010). Early
life history of snow crab including larval drift between offshore and inshore
sites, nursery grounds, settling and occurrence of benthic stages is unknown
or poorly understood in the assessment area. Genetic analysis showed that
snow crab in West Greenland waters differ significantly from those in western
part of Davis Strait (Atlantic Canada), whereas no difference was found
between inshore and offshore site subpopulations within this assessment area
(Puebla et al. 2008).
Population size: The population occurring in the assessment area has an unfavourable
conservation status due to years of high fishing pressure.
Sensitivity and impacts of oil spill: Boertmann et al. (2009) assumed that fish
and shrimp larvae are more sensitive to oil than adults. Larvae of snow crabs
might be sensitive to an oil spill as well and consequences for survival, the
impacts of annual recruitment strength and subsequent population size are
unknown. In contrast to pelagic fish and crustaceans, benthic stage snow
crabs are observed not to migrate over larger distances in Greenland, but are
believed to be stationary. Change in habitats through chemical pollution is
therefore of particular interest in relation to snow crab, as they might not be
able to avoid contaminated sediment. A laboratory study on habitat preferences
for juvenile king crabs (Paralithodes camtschaticus) and Tanner crabs
(Chionoecetes bairdi) exposed to oil has led to the suggestion that exposure
time isthat likely to be longer for species intimately associated with sediment
and pollution might play a larger role in crab population decline
(Moles & Stone 2002).
Knowledge gaps: Early life history of snow crab including larval drift between
offshore and inshore sites and along the Greenland west coast, nursery
grounds, settling and occurrence of benthic stages is unknown or poorly understood
in the assessment area.
Greenland Halibut, Reinhardtius hippoglossoides
Biology: Greenland halibut is a slow growing deep-water flatfish that is
widely distributed in the north Atlantic including Baffin Bay, Davis Strait
and Labrador Sea and inshore areas along the entire west coast of Greenland
and inshore areas at eastern Canada. The main spawning ground is assumed
to be located in the central part of the Davis Strait south of the sill between
Greenland and Baffin Island where spawning takes place in early winter.
The assumption is based on development of ovaries (Jørgensen 1997,
Gundersen et al. 2010) and observation of eggs (Smidt 1969). Most sampling
has been conducted at depths down to about 1,500 m but no females in
spawning conditions have ever been observed and it is possible that spawning
takes place at depths greater than 1500 m, probably around 62°30’N -
63°30’N. From the spawning grounds eggs and larvae drift through the assessment
area with the West Greenland Current towards the settling areas.
Early stage eggs are found between 240-640 m (Smidt 1969) and larvae are
primarily found at 13-40 m (Simonsen & Gundersen 2005). The pelagic stage
lasts more than six months (Smidt 1969). The larvae settle in August-