TECHNICAL REPORT OF THE SCALLOP PROJECT CRUISES. I. CRUISE I (DECEMBER 4 TO 9, 1995)

Abstract

Main technical results and original data of Cruise I of the Scallop Project (December 4 to 9, 1995) are presented in this Report. Sampling sites were distributed along seven transects, between the 30 and 50 meters isobaths, according to information of previous surveys carried out in 1975. Salinity and temperature of the water column, and sediment samples were obtained at each sampling site for a physical characterisation of the scallop grounds. Two types of beam-trawl and one dredge were tested to catch scallops and benthic samples. Salinity and temperature showed an important gradient, with high temperatures and low salinities at surface waters, and low temperature and high salinities at bottom waters. Sediments were constituted by pure fine to very fine sands. Organic matter and calcium carbonate content, together with other statistical sediment parameters, showed a bathymetrical variation. Along the study area, two beds were found, at SSE of Bom Abrigo Island (São Paulo State) and E of São Francisco do Sul Island (Santa Catarina State), both between 36 and 40 m depth. Very low scallop catches were probably related to a total depletion of the original stock. Future cruises will try to determine the efficiencies of the beam-trawl for a real estimation of scallops densities.