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Fresh Water Killing Off Oysters In Upper Chesapeake Bay

BALTIMORE (WJZ)—Way too much of a good thing is officially the cause for a die-off of oysters in the upper Chesapeake.

Alex DeMetrick reports too much rain washed away the salty water oysters need to survive.

Department of Natural Resources scientists are in the upper Chesapeake looking for oysters, after reports from watermen that this part of the bay has experienced a significant die-off.

And in at least isolated pockets, there are no live oysters.

"All the oysters are dead.  This is a dead oyster. Fairly recently dead. It probably died after the tropical storms when the salinity dropped," said Mitch Tarnowski, DNR senior biologist.

Tropical Storm Lee alone pumped 29 trillion gallons of fresh water into the bay, pushing out saltier water oysters need.

"When the salinity gets too low they are not able to maintain the normal processes that occur within tissue to keep them alive," said Mike Naylor, DNR Shellfish program.

Oyster die-offs like this have happened five times before in the past century.  They are not quick to recover.

"It may take another 10 years before we get more baby oysters up here," Tarnowski said.

But south of the Bay Bridge in saltier water, the news is better. Oyster stocks are doing well and are being harvested. That's not much help for watermen who work the upper bay.

"The crew found every oyster dead, and right then I knew we were in trouble," said Barry Sweitzer, waterman.

And it's not heartening for those trying to restore oysters, when all that comes up are empty shells called boxes.

"It's pretty depressing when you hear the death rattle as the boxes hit the table," Tarnowski said.

The state will look into restocking affected areas with baby oysters raised in the lab--a process that will take years to produce enough oysters to harvest.

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