Friday, February 20, 2015

Female Blue Crabs Go the Extra Mile

The Washington Post recently ran an article on the status of blue crabs in Chesapeake Bay. The first few paragraphs and a link to the full article are posted below. The Post site has a nice graphic of the blue crab life cycle.

 February 12  
Deep under the cold, dark waters of the Chesapeake Bay, the answer to whether the decimated blue crab population can survive lies buried in mud.
Tens of millions of female crabs are scattered across the floor of the lower bay in southern Virginia, where the estuary pours into the Atlantic Ocean, waiting out winter for one of the most important events in their short lives. When spring comes, they will inch closer to the ocean with billions of eggs.
It’s a critical time because the blue crab population is reeling, facing some of the lowest numbers in history. Officials are desperately hoping that steps taken to protect females last year will allow the fishery to rebound from the edge of disaster. But those efforts are also mired in a debate over the best way to protect the crabs.
As females go, so go blue crabs. Last year, scientists estimated that there were only 68.5 million females old enough to spawn, far below the 215 million that officials say are needed to overcome natural threats such as predators and cold — and human threats such as commercial overfishing — without depleting the population. This year’s count is underway by Maryland and Virginia scientists at 1,500 locations.
The blue crab, Maryland’s state crustacean and a symbol of pride for the region as much as a resource, is more threatened now than at any time since biologists started to record numbers in the late 1940s. Both watermen and state officials are deeply worried about blue crabs’ future. Sixty years ago, the Chesapeake Bay yielded 75 percent of the crabs harvested in the United States; now the withered stock yields about 35 percent, according to a report by the Maryland’s natural resources department.
Some watermen say the steps taken by Virginia, Maryland and the Potomac River Fisheries Commission to rescue crabs after the population’s free fall in 2008 haven’t worked. The states cut the number of females that can be fished by about 30 percent. When the stock rose only to fall hard again last year, Virginia cut the number of females that could be fished by an additional 10 percent during the spawning run.
Smithsonian scientists worry that efforts to save females might produce a serious side effect: overfishing males. When male crabs decline, those remaining mate more often, and sometimes can’t regenerate their sperm supply quickly enough, according to a study by the Smithsonian Environmental Research Center.
Read the rest of the article at the Washington Post by clicking here.

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