Heavy rains this spring, not this September, killed most of the oysters in the upper Chesapeake Bay.
That’s according to preliminary findings from the Maryland Department of Natural Resources’ annual fall oyster survey.
Michael Naylor, director of the department’s shellfish program, says record spring rain made the upper bay too fresh for too long. Naylor says surveyors can tell how long oysters have been dead by the shells. Most were already home to organisms that only grow and reproduce in the summer. And those organisms were still alive, so the oysters were not killed by low oxygen levels or buried in sediment, which would also have killed the organisms.
The survey found 79 percent of oysters in four northern bars were dead, while mortality was low below the Bay Bridge.