Soft Shell Crab

TAXONOMY

Phylum: Mollusca
Class: Bivalvia
Order: Myoida
Family: Myidae

ECOLOGICAL DATA

Distribution: introduced from Atlantic around 1879; common along entire B.C. coast in protected estuaries and bays, often in brackish waters.

Habitat: soft muddy substrates in estuaries; common in eelgrass beds; survives in high organic-low oxygen conditions; poor digger, burrows to maximum of 20 cm; may occur with butter clams; planktonic larvae dispersed by currents; adults remain in same burrow for life.

Tidal elevation: upper tidal to mid-tide range; on Atlantic coast extends to 9 m subtidal depth.

Food: suspension feeder; mainly phytoplankton and detritus.

Predators: diving ducks, gulls, crows, cormorants, and fishes.

GROWTH RATE

Sexual maturity at 2-3 years (25 mm); grow to 7.5 cm in 3 yr; reach up to 10 cm in B.C.

FISHERY

Occasionally taken in commercial and sport fisheries; not abundant enough to support commercial fishery; sewage pollution and paralytic shellfish poisoning (PSP) have closed large areas of coast to harvesting.

REFERENCES

Bernard, F.R. 1983. Catalogue of the living bivalvia of the eastern Pacific Ocean: Bering Strait to Cape Horn. Can. Spec. Publ. Fish. Aquat. Sci. 61: 57.

Bourne, N. 1986. Intertidal clams, p. 22-31. In G.S. Jamieson and K. Francis [ed.] Invertebrate and marine plant resources of British Columbia. Can. Spec. Publ. Fish. Aquat. Sci. 91.

Cheney, D.P., and T.F. Mumford, Jr. 1986. Shellfish and seaweed harvests of Puget Sound. Wash. Sea Grant Program, Univ. Wash. Press, Seattle: 164 p.

Hawkins, C.M. 1986. The soft-shell clam. Underwater World, Fish. Oceans Can., Ottawa: 6 p.

Jamieson, G.S. 1986. Paralytic shellfish poisoning, p. 44-46. In G.S. Jamieson and K. Francis [ed.] Invertebrate and marine plant resources of British Columbia. Can. Spec. Publ. Fish. Aquat. Sci. 91.

Kozloff, E.N. 1983. Seashore life of the northern Pacific coast. Douglas & McIntyre, Vancouver: 294-295.

Quayle, D.B. 1978. The intertidal bivalves of British Columbia. B.C. Prov. Mus. Handb. 17: 79-80.

Quayle, D.B., and N. Bourne. 1972. The clam fisheries of British Columbia. Fish. Res. Board Can. Bull. 179: 60 p.