Hydraulic dredge discards of the clam (Chamelea gallina) fishery in the western Adriatic Sea, Italy

This study provides a qualitative and quantitative assessment of the discards produced by the commercial hydraulic dredging fleet targeting the clam, Chamelea gallina, in two Maritime Districts of the Adriatic Sea (Italy). Overall discards comprised just under 50% of total catch in both Maritime Districts, approximately 30% of which were undersized target species (<25 mm) and 20% other benthic invertebrates, whilst fish were poorly represented. Significant differences in the proportions of the different catch components were found between the two Maritime Districts considered. Similarly, the size-frequencies of landed catch were significantly different between Districts. Great variability in overall catch composition from one Zone to another within one District was detected, emphasising the importance of a Zone-based management, rather than a District-based management. Analysis of the invertebrate component of discards revealed a clear segregation of the benthic community according to depth. Future management plans should thus incorporate a bathymetric component and future research should focus on identifying species particularly sensitive to this kind of disturbance.