Comparing Economic Dynamics of Oyster and Mussel Farming, with Particular Emphasis on their Profitability: An Application in the Mont-Saint-Michel Bay (France)

This paper sets out an evaluation of profitability differentials within shellfish farming activities of the\ud Mont-Saint-Michel Bay. The objective is to examine whether profitability differentials have\ud consequences in terms of economic dynamics and of management arrangements. The paper divides into\ud four parts. The first part presents a retrospective analysis of shellfish farming activities in the Bay, which\ud are nowadays dominated by Pacific oyster (Crassostrea gigas) and Blue mussel (Mytilus edulis). The\ud second part consists in measuring the economic performances of enterprises. The indicators are based on\ud the data provided by two surveys conducted in 2002 (mussel-farming) and 2004 (oyster-farming);\ud methodological difficulties due in particular to the status of shellfish farming land are addressed here. The\ud third part examines the determinants of the profitability for each sector, the profitability being the result\ud of a combination of factors such as natural productivity, technical practices, production costs and products\ud pricing. The last part discusses the implications of profitability differentials. Profitability differentials\ud seem to be correctly reflected in land prices, but not necessarily in the annual ground fees perceived by\ud the Administration. However, shellfish farming profitability should be included in redistributive\ud mechanisms, as its relation to primary resources exploitation and management is not neutral. Thus,\ud empirical evidence suggests that profitability differentials create bargaining powers which influence the\ud results of negotiation between actors regarding the management of the Mont-Saint-Michel Bay