Anthony Sturbois

Modelling Fishing Grounds of Cerastoderma edule L. for Sustainable Clam Harvesting in the Bay of Saint-Brieuc

The cockle Cerastoderma edule has been collected by traditional fishing methods for many centuries in the Bay of Saint-Brieuc. Since 2001, the National Natural Reserve of the Bay of Saint-Brieuc has carried out annual stock assessments and mapping of cockle harvesting grounds. This assessment takes place between the end of July and middle of August at 131 stations that are located 500 m apart covering an area of 2,900 ha along the inter-tidal foreshore. At each site, cockles are harvested within a square of 0.25 m² and measured in a laboratory. This assessment process has led to the development of a predictive model of the harvesting grounds using the growth stages of each individual. The model provides benefits for managers and local authorities by: 1) allowing mid-term predictions (1-2 years) on harvesting in the cockle grounds which allows professionals and scientists to rule on the next fishing season; 2) assessing quickly the impact of any change to the minimum legal fishing size on the fishable part of the cockle harvesting ground; and 3) estimating the potential impact of a management project which could interfere with the way of the fishing ground functions. This approach can be easily transferred to other co-management schemes of cockle fishing grounds.

Keywords: cockle, traditional harvesting, management, modelling, fishing ground, nature reserve.

Figure: At each site, cockles are harvested within a square of 0.25 m² and measured in a laboratory. The shell length of each cockle is measured to the nearest 0.1 mm with a vernier calliper. © Anthony Sturbois.