Pollution Is a Factor in Crab Decline
Monday, December 29, 2008; 1:59 PM
Pollution and overfishing have caused devastating declines in Chesapeake Bay blue crabs, and the federal government has been undercutting state efforts to restore the bay by failing to enforce environmental laws, a conservation group said Monday.
The Environmental Protection Agency should impose a regulatory cap on the amount of pollution that can enter the nation's largest estuary and enforce the Federal Clean Water Act, the report by the Chesapeake Bay Foundation concluded. Maryland, Virginia and Pennsylvania must also do more to control pollution from agricultural runoff, the report said.
"I think the most important thing right now is for the federal Environmental Protection Agency to do it's job," said William Baker, president of the Chesapeake Bay Foundation. "That will help the states reinforce the efforts of the states."
The report, titled "Bad Water and the Decline of Blue Crabs in the Chesapeake Bay," cites pollution and overfishing -- particularly of female blue crabs -- as the two causes of the problem. While as many as 791 million blue crabs were estimated to live in the bay in 1990, their numbers plunged to about 260 million at the end of 2007.
Among the report's key findings:
--Low-oxygen "dead zones" have killed crab food, preventing the growth of 75,000 metric tons of clams and worms a year -- enough to support more than 60 million blue crabs a year.
--Nitrogen and phosphorous pollution are causing algal blooms that kill underwater grasses needed for crabs to hide from predators. More than half of the bay's eelgrass has died since the 1970s.
--Watermen have overfished the bay by catching an average of 62 percent of the bay's blue crabs each year over the last decade -- far above the 46 percent scientists say are sustainable.
--A cleaner bay could revive crab populations enough for watermen to catch the same number they are harvesting now without going over the 46 percent threshold.
The report was based on government data, scientific papers and interviews with leading crab researchers and water quality experts.
"We have been hearing the same song for 25 years," Baker said. "There is nothing different other than the species of crabs oysters claims are declining. When are we going to learn?"
Scientific understanding of the bay's woes is vast, Baker said, and all that's lacking to revive its waters is the political will to do what's necessary to reduce pollution.