Publication Abstract

Factors in the life history of the edible crab (Cancer pagurus L.) that influence modelling and management

D.B. Bennett

The United Kingdom has implemented progressive changes in the management regulations of the edible crab (Cancer pagurus). Various aspects of crab life history are reviewed to show how they have influenced the fisheries for this species and stock management. Aspects of the reproductive cycle, including size at maturity and spawning strategy and the spatial distribution of larvae and juveniles are poorly known. Males grow faster than females, and there appear to be real differences in growth rates. Tagging studies indicate that extensive movements are made by mature females. Catch rates of crabs are influenced by moulting and breeding cycles. The population structure is complex with seasonal and spatial variation in both size composition and sex ratio. Stock relationships are difficult to interpret. Yield-per-recruit modelling has been used to investigate management options. Models used have included various life history factors, explicitly or implicitly, with some data assumptions. Nevertheless, a pragmatic approach to fishery management has resulted in several changes to minimum landing size regulations in the UK. These consider sexual and regional variation of biological factors such as growth. There exists a risk of recruitment overfishing arising from the exploitation of prespawners, and interactions with other fishing gears and seabed uses like aggregate dredging.

Reference:

D.B. Bennett, 1995. Factors in the life history of the edible crab (Cancer pagurus L.) that influence modelling and management. ICES Marine Science Symposia. 199: 89-98.