As he did in Cod and Salt, Mark Kurlansky uses a foodstuff to tell a larger tale, in this case the depressing history of New York City's befouled waterways, which once teemed with enormous, succulent oysters. Indeed, portions of the city are built on Indian oyster-shell middens, and as recently as a century ago, New Yorkers feasted on the cheap, plentiful bivalves, which were peddled from pushcarts and sold in all-you-can-eat oyster cellars. Kurlansky packs The Big Oyster with terrific anecdotes and vintage recipes that suggest the creature's onetime abundance. (A mid-19th century recipe for pickled oysters begins: ''Take a hundred and fifty fine large oysters...'') But he is equally graphic in describing the pollution that put an end to all that. Only a handful of oysters survive in New York's filthy waters, and those, Kurlansky notes, are unfit to eat.