Whose ragged claws are those scuttling across the floor of the Chesapeake Bay? After learning that two Chinese mitten crabs were caught near the mouth of the Patapsco River, state marine biologists are wondering if the interlopers merely hitched rides into Maryland waters aboard tankers or are part of a larger established invasion that might throw the bay's ecosystem out of kilter. Great. Just what the Chesapeake needs. Remember the snakehead fish? The zebra mussel? The rodent-like nutria? How about Phragmites, the rapacious reed that spread around the bay and crowded out indigenous plants? Now it's a crustacean with gloves.
Not that everybody thinks the Chesapeake's blue crab is a thing of beauty, but the mitten crab, with its saucer-shaped body and its pair of large, bristle-covered pincers, is downright repulsive looking. Still, appearance is not the problem. The mitten crab has gotten a clawhold in parts of Germany and England and on the West Coast. It has grown to such numbers that it clogs the water intake pipes - it almost shut down southern California's water supply in 1998 - and steals bait from sports fishermen.
When the crab isn't making a nuisance of itself in the water, it can damage riverbanks by burrowing into the soil. As undesirable as its presence is in the Chesapeake, scientists do not believe it poses a threat to bay crabs. The mitten crab may be a serious pest, but it does not eat other crabs and, in a claw-to-claw encounter, is apparently no match for the feisty Chesapeake blue.
Although the mitten crab is a delicacy in its native China, it has not captured the imagination of diners elsewhere and nobody envisions sitting down to a steaming trayful at an Inner Harbor restaurant. Besides, it is a federal offense to possess the crab in the United States without a permit. State natural resources officials have posted a watch on the mitten crab and are working with watermen to keep an eye out for more appearances.
If it turns out that there are no other mitten crabs in the bay, that would be good news. Until then, commercial and recreational crabbers who catch one are asked to hand it over to the Dept. of Natural Resources or the Smithsonian Environmental Research Center. This is not a crab we want to find a home in the Chesapeake.