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The archipelago of Chausey is a Marine Protected Area which 5000 ha of Public Maritime Domain have been entrusted by the Conservatoire du Littoral.
The general objectives of the intervention of the Conservatoire du Littoral in the archipelago of Chausey improving knowledge of marine environments, biodiversity conservation, and information / mediation on site with users. These different orientations are developed in equity management plan whose implementation is closely shared with the Syndicat Mixte Espaces Littoraux de la Manche (Symel).
In the archipelago of Chausey, the praire (Venus verrucosa) undergoes fishing pressure by dredging and recreational low water fishing. Antagonism on this fishing crystallized and local information gaps and scientific management have opened the possibility to lay the basis for collaborative management of clam populations in the archipelago.
The approach developed in this project aimed to better understand the interactions between the state of praire populations in the archipelago and the levels and uses of catches. The multidisciplinary approach aims to bring the local elements of knowledge interaction at work, to propose management rules and shared tools followed.

On the one hand, the work carried out on praire and trophic resource has helped to bring new scientific knowledge on the status of populations across Chausey.
The analysis of the dynamics of populations of praire in Chausey archipelago reveals high variability of growth performance at small spatial scales (<km).
These variations are explained by the complex hydrosedimentary dynamics in the archipelago. If the quality of the trophic resource seems less involved, it nevertheless appears that the water column is locally enriched in non-lipid substances dissolved from brown weeds in the archipelago. The analysis of age structures of populations show a strong inter-annual variability in recruitment of praire in the archipelago.
Recommendations of scientific monitoring are removed from these 2 years, including vulnerability to fishing pressure at certain sites in the archipelago with low growing performance.

On the other hand, the work carried out on the characterization of fishing practices helped to bring quantitative, qualitative and behavioral elements.
The professional catches, made by dredging, could not be conducted without access to local data.
However, the characterization of the uses of recreational fishing can provide fishing pressure assessment on the praire across the archipelago.
The influence of the weather, seasonality, geographical spread of the activity, but also the intensity and evaluation of clams catches, changes in rules application are figures supplied by the 2nd approach.
Low water fishing pressure across the archipelago can be estimated in terms of space and quantity.

Even if it is not possible at this stage to develop real indicators for monitoring interactions between bivalves resource and recreational fishing, some interesting possibilities emerge.
The sampling tool developed (Symel Dredge) and allometric relationships defined in the biological study now allow to estimate exploitable populations in the next years on the sites. This work can be conducted with professional fishermen.partnership.
Annual monitoring can be initiated to test the prediction of resources avalaible for porfesisonnalet leisure low water fishing.
The availability of these tools allows today to consider objective exploration of interactions uses / samples / resources. Their implementation must allow a meaningful assessment of future situation and, hence, knowledge sharing, rules, or shared management.