Publication Abstract

Larvae surveys of edible crab (Cancer pagurus) off the east coast of England: implications for stock structure and management

Larvae surveys of edible crab (Cancer pagurus) off the east coast of England: implications for stock structure and management

D.R. Eaton, J.T. Addison, S.P. Milligan, J. Brown and L.J. Fernand

Edible crab (Cancer pagurus) fishing areas are distributed along the English east coast with significant offshore fisheries off North Norfolk and the Humber. Previous tagging studies showed directed northerly movements of mature females suggesting that recruitment was strongly influenced by larval drift southwards. Comparison of results from a larvae survey undertaken in July 1999 with two previous surveys in 1976 and 1993 suggests that the epicentre of crab spawning, as perceived by the density of stage I zoea, was consistent over the 23-year period, being centred to the south-west of the Dogger Bank approximately 70 km offshore. Recent hydrographical evidence suggests that there is a seasonal jet-like circulation which extends southwards along the coast as far as Flamborough Head before turning offshore along the northern edge of the Dogger Bank. The front forms in April/May and breaks down again in October/November, and once established there is very little interchange between water masses north and south of the Dogger Bank. South of the Dogger Bank, there appears to be a fairly stable water mass with only a slow residual drift in an easterly direction. The areas to the north and south of the front are effectively isolated, therefore during the period of crab spawning activity challenging the accepted wisdom that the main crab fishery is reliant upon recruitment from spawning areas to the north. The crab population south of the Dogger Bank may be effectively a separate, self-sustaining stock and may provide recruitment of adult crabs to northern areas.

Reference:

D.R. Eaton, J.T. Addison, S.P. Milligan, J. Brown and L.J. Fernand, 2001. Larvae surveys of edible crab (Cancer pagurus) off the east coast of England: implications for stock structure and management. ICES CM 2001/J:14. 10pp.

D.R. Eaton*, J.T. Addison*, S.P. Milligan*, J. Brown* and L.J. Fernand*

ICES CM 2001/J:14: 10pp