Les pêcheries de buccin (Buccinum undatum L. : Gastropoda) du Golfe Normand-Breton. Eléments de gestion de la ressource

The whelk (Buccinum undatum) fisheries in the gulf between Brittany and Normandy have grown quickly over the past ten years. In 1983, 35 potters and 14 dories from Granville harbour and the Blainville maritime station landed 3,900 tonnes of whelk (for a value of 7.5 million francs). In spite of a sharp drop in profitability, the number of fishers is still growing. This study aimed to provide decision-making elements for rational management of the resource : stock abundance, catches per unit effort, mortality due to fishing effort and biological properties. In order to assess the impact of measures to organise the fishing effort on total catches in balance, two predictive models were used: Pella and Tomlinson's generalised production model and Ricker's analytical model. Predictions from the Ricker model were combined with an economic model assimilating the main accountancy items from the operating statement of the "average boat" from Granville harbour. The results obtained indicate that in the short term, whelk fishing will not remain profitable if current trends continue (rising number of fishers and stagnating selling price). This trend suggests that measures to regulate the fishing effort be implemented, particularly a limit on the number of fishers.