Depuration of molluscs

Abstract

The experimental system put up at SEAFDEC [Southeast Asian Fisheries Development Center; Philippines] consisted of six rectangular (96 x 196 x 42 cm) fiberglass-coated tanks made of marine plywood. It can depurate about 230 to 310 kg bivalves in two days. Initial findings showed that under normal seawater conditions (salinity 29-32 ppt, temperature 27-30 degrees Celsius; oxygen content 3-6.2 mg/L; and pH 7.4-8.3) and moderate rate of flow (7-10 L/min), highly contaminated oysters (MPN 1.0 x 10 to the fifth power to 2.0 x 10 to the sixth power/100 g meat) can be depurated within 48 hr or less. A short flume type of tank with a volume of about 250 L was designed, tested and showed to cleanse oysters under normal conditions in only 24 hr with a flow rate of 7L/min and with very little resulting mortality. More important, the tank can be lifted and moved by only two men of average body built.