Selectivity of Striped Venus Clam (Chamelea gallina) in the Sieving Process of the Mediterranean Hydraulic Dredge Fisheries

The striped venus clam (Chamelea gallina) is the target of a large fleet of hydraulic dredgers operating in the Adriatic Sea (Mediterranean). The clam stocks are now showing signs of overexploitation, calling for an immediate management action. Despite this relatively little scientific work has been done to assess the selectivity of the hydraulic dredges. Selective process in the hydraulic dredge fisheries has two stages: the first takes place at sea while fishing, the second occurs on board the vessel. We investigated the striped venus clam selectivity occurring during the sieving process on board the hydraulic dredge in the Adriatic fisheries. The sieving tool consists of sequential holed grids made with holes of different diameters. This study was undertaken to analyse the effect of the sieve-diameter and the speed of sieving on the selectivity, with a view to suggesting management measures. Selectivity was measured using the same approach followed in the covered codend technique taking into account the between-haul variation in selectivity. The results allow to infer both the effect of different diameters in the sequential grids and the use of different sieving speeds. The results attained in the present study can assist fisheries managers in the revision of current legislation.