"OAKDALE, N.Y. — The Great South Bay, flanked by Fire Island and the South Shore of Long Island, once produced half the shellfish consumed in the United States, and supported 6,000 jobs in the early 1970s.
Since then, the health of the bay has declined. Housing development meant more septic tanks depositing more nitrogen in the ground. The nitrogen flowed to rivers and the Great South Bay, leading to algae blooms. It depleted salt marshes that serve as fish habitat and suppressed oxygen levels.
One result is that the shellfish industry has all but collapsed. The annual harvest of hard clams, for example, has fallen more than 90 percent since 1980."