DURHAM, N.H. (AP) — When the pandemic hit, oyster farmers found the restaurants that sold their bivalves had largely closed. Many faced economic ruin until a conservation group along with two federal agencies offered to buy up millions of oysters in New England, the Mid-Atlantic and Washington state as part of a program to restore shellfish reefs at 20 locations. The Nature Conservancy is spending $2 million over two years to buy more than 5 million oysters for restoration efforts. The oyster reefs provide critical habitat for fish and help protect shorelines from erosion. Oysters filter out pollutants and excess nutrients from the water.