Aménagement hydrauliques pour l'ostréiculture

Hydraulic installations for oyster farms

Ingénieur en Chef du Génie Rural, des Eaux et des Forêts, Directeur Départemental de l'Agriculture de la Vendée.

Résumé

Developments in oyster production methods have resulted from the oyster breeders' wish to intensify their output and to protect the oysters against the hazards associated with present oyster beds in the sea, such as currents, storms, silting and frost. There are four phases of oyster production, as follows:- (i) Collecting the brood; (ii) Breeding the oysters; (iii) Fattening and refining; (iv) Final treatment and packing. The present tendency is for oysters to be bred in proteeted heds with wholly or partly controlled water conditions. Water requirements for present-day methods are as follow:Depth of water: 60 centimetres; Water renewal rate: If possible daily, with 0.4 to 0.6 cubic metre per square metre of bed area. Fattening and refining take place in fattening ponds with water renewal strictly controlled to within the following limits:- Depth of water: 30 to 40 centimetres; Water reneval rate: Total renewal twice or three times monthly. This takes two or three days ta complete at a rate of 0.1 to 0.2 cubic metre per square metre of fattening pool area daily. Two developments in Aiguillon and Bourgneuf Bays in the Vendée region are based on polders recently reclaimed from the sea. Their respective sizes are 55 hectares and 194 hectares. They provide examples of the type of arrangements that can he adopted in arder to meet the requirements for hydraulic installations for oyster fanns, the most important of wlüch are as follows:- (i) The feed water must be brought in from an area known to be wholesome; (ii) The feed water must be adequately sally; (iii) Separate supply and outlet networks are necessary to prevent re-use of water from the fattening ponds. The installations also feature intake and discharge works build on mud at the water-front.