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

1990) and then north (mid-2000s) in West Greenland waters, is poorly understood.
Whether this movement was caused by increased predation affected
by the return of cod in southern Greenland, increased bottom temperatures
or other factors is unknown. The food web interaction between northern
shrimp and their prey and predators is also poorly understood.
Snow crab, Chionoecetes opilio
Biology: Snow crab (Chionoecetes opilio O. Fabricius; Brachyura, Majidae) has a
wide distribution and is considered to be of arctic-boreal biogeographic affinity,
because it does not usually extend north of the Arctic Circle into the
High Arctic (Squires 1990); although there are two exceptions (Paul & Paul
1997, Burmeister 2002). Snow crab mainly inhabits grounds of mud or sandmud
substrate at depths from 30 to 1,400 m, where bottom temperature remains
–1.5 to 4°C year round (e.g., Squires 1990, Dawe & Colbourne 2002).
Snow crab may be physiologically constrained to these temperatures as its
energy budget becomes negative outside of the range due to reduced feeding
and rising metabolic costs (Foyle et al. 1989, Thompson & Hawryluk
1990).
As with other brachyuran crabs, the snow crab life cycle features a planktonic
larval phase and a benthic phase with separate sexes. The mating system
is complex, with a distinct male dominance hierarchy resulting from intense
sexual competition favouring larger males (Donaldson & Adams 1989, Elner
& Beninger 1995, Sainte-Marie et al. 1999, Sainte-Marie & Sainte-Marie 1999).
Females can reproduce several times in their lifetime, may be quite polygamous
and have a pair of spermathecae for extended storage of sperm (Elner
& Beninger 1995, Sainte-Marie et al. 2000). It is accepted that female snow
crab may produce more than one viable brood from spermatophores stored
in their spermathecae (Sainte-Marie 1993, Sainte-Marie & Carriere 1995).
Eggs are incubated beneath the female’s abdomen and hatching and larval
release occur during late spring or early summer just prior to extrusion of
the new clutch of eggs, which may or may not be preceded by mating.
The larvae proceed through three planktonic stages (zoeae I-II, megalops)
and settle on the bottom in autumn at a carapace width (CW) of approximately
3 mm. The snow crab spends the rest of its life on the sea floor, where
it preys on fish, clams, polychaetes and other worms, brittle stars, shrimp,
other crabs and its own congeners (Lefebvre & Brêthes 1991, Sainte-Marie et
al. 1997). Crabs grow by moulting, in late winter or spring in the case of
larger crabs, and both males and females have a terminal moult to adulthood
(i.e. functional sexual maturity), which occurs over a wide size interval
(Conan & Comeau 1986, Sainte-Marie & Hazel 1992, Sainte-Marie 1993,
Sainte-Marie et al. 1999). There is a large sexual size/age dimorphism at
adulthood, with males living up to approximately 15–16 years and females
up to about 11–12 years after settlement (Sainte-Marie et al. 1995, Alunno-
Bruscia & Sainte-Marie 1998, Comeau et al. 1998). The males enter the fishery
approximately 8-9 years after settlement to benthic stage.
Distribution: The most northerly record of snow crab is from Greenland,
where the species is distributed along the west coast between 60°C and 74°N
in both offshore and inshore (fjords) locations (Burmeister 2002). Greenland
fjord populations are possibly isolated at the benthic stage, as appears to be
the case in Canadian fjords (Conan & Comeau 1986, Bernard Sainte-Marie,
MLI, Canada, pers. comm.). In Greenland, snow crab is generally found at
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