“Oysters usually lay millions of eggs and the larvae drift to distant places and settle where the substrata is most favourable,” explained Dr Vinay Deshmukh principal scientist of Central Marine Fisheries Research Institute (CMFRI), Mumbai, whose team is currently studying the newly-found species. He said the new species have also been found in profusion in the northern waters of Goa, Karnataka and Gujarat.
Pointing out that oysters were aplenty in the Mahim creek in the 1960s, Deshmukh said, “Earlier the Mahim creek was thriving with oysters and clams, but oysters were of a much smaller variety called crassostrea cuculata. They only grew up to 2 or 3 inches in size. The new species, on the contrary, can become as large as 5 inches”.
His team has short-listed two varieties — crassostrea graphoides or crassostrea madresensis — which the oysters could belong to. “The two species though mostly similar have a few conflicting qualities. We are finding out which one are these oysters,” they said.
On April 5, Newsline reported the appearance of oysters and clams in the Mahim Bay nearly 40 years after pollution, chemical waste and grime destroyed its marine fauna. According to Deshmukh, the return of life forms indicated existence of oxygen in the water.
He stated that about three years ago, the BMC had embarked upon a marine outfall project, in which a diffuser carried semi-treated sewage into mid-sea, thus diluting its toxicity. “It is probably a result of this or the clean-up of Mithi river, but in my recent visits to the Mahim and Dadar beaches, I also noticed the foul smell has reduced considerably.”
However, the scientist warned against consumption of the oysters at this time. “Usually, oysters feed on organic matter like animal wastes. However, in a polluted environment, non-biodegradable substances, including chemical wastes, may sometimes accumulate in their body making it unsafe for human consumption. The oysters may not be edible in the immediate future,” he said.
Meanwhile, a local fisherman from Mahim said, “The fact that the oysters have begun depositing in the water itself means that the water is getting unpolluted. However, the oysters are not growing in such quantities that we can sell them immediately. It will take at least 20 years for us to undertake oyster farming.”
nitya.kaushik@expressindia.com