ABSTRACT

Many species of oysters are found in India. The shells of the Ostreida are so variable that identification is difficult. Many species are probably synonyms, and some others probably will be when the subject receives adequate attention. The common edible oysters usually settle on hard substrates such as boulders, coral, sandstone, or other oyster shells. Spawning activity is restricted to November and December and a supplementary period in about March and April, and is induced by optimum salinity. The growth rate is not affected by short, tidal fluctuations in salinity. In deeper areas, techniques somewhat similar to those for harvesting green and brown mussels are used, whereby dredges are used to dislodge the oysters from the substratum. Metals that are accumulated by oysters include zinc, copper, and iron; concentrations in the environment and in oyster tissue vary both seasonally and spatially.