Scientists have found Chinese mitten crabs mating and producing eggs in the Chesapeake and Delaware bays - evidence that the alien species is likely breeding and established on the East Coast. Two hairy-clawed invaders were caught recently by watermen, one south of Kent Island and one in the upper Delaware Bay, raising to 10 the number confirmed in the region over the past three years.
More significantly, the two were the first females found on the East Coast. Both showed evidence of recent mating, and the Delaware crab was carrying eggs, said Greg Ruiz, senior scientist at the Smithsonian Environmental Research Center in Edgewater. "It suggests they are certainly reproducing, mating and producing eggs, but we don't know if it's a self-sustaining population," said Ruiz. "It's a concern that we continue to find more crabs."
Authorities in Maryland and other Eastern states have broadcast alerts for Chinese mitten crabs because the creatures often stow away in the ballast water of ships, then reproduce in excessive numbers in their new environment.
Their burrowing has caused erosion in a few of their adoptive homes, such as San Francisco and England. They can also clog water pipes and fight for food with native species. One concern is they could compete with Chesapeake blue crabs.
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