Chinese Mitten Crab Fear

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The Chinese mitten crab, universally feared by invasive species experts in the United States, has been found in the Hudson River near the Tappan Zee Bridge, scientists monitoring the crustacean said this week. Carin D. Ferrante, of the Smithsonian Environmental Research Center in Edgewater, Maryland., said the male specimen was pulled from commercial crab gear near Nyack earlier this month. It is the first confirmed discovery of the long-legged invader in New York state, Ferrante said

Scientists have been preparing for increased reports of the science fiction-like creature — named for its hairy, mitten-like claws — after four invaders were discovered in Delaware Bay last month. That discovery, which followed the capture of three mitten crabs in the Chesapeake Bay since 2005, prompted an East Coast-wide alert to fishermen and boaters. "We think there are real concerns, but part of the problem is we honestly don't know what is going to happen," Ferrante said. "That's why we established this watch." Experts believe the crabs might have been introduced from ballast water of ocean liners, the aquarium trade, or through the illegal food market.

In China, the species is considered a culinary and medicinal delicacy — its eggs are thought to be aphrodisiacs. But outside Asia, the mitten crab has caused havoc, burrowing into and eroding stream banks, destroying levees and overtaking other aquatic species. The first North American sighting was in the Great Lakes in 1965, when a mitten crab was sucked into an intake pipe on the Detroit River. Additional specimens have been caught in the St. Lawrence River, the Columbia River in Oregon and along the Gulf Coast. The only established population of mitten crabs in the United States is in the San Francisco Bay estuary. Just eight years after those crabs were discovered in 1992, hundreds of thousands were being reported annually. The experience there has some East Coast researchers bracing for a similar infestation.Should mitten crab populations mimic West Coast booms, increased inspections of riverside infrastructures — like train tracks and buildings — could become necessary, experts say.

Less certain is how the mitten crabs might compete for food with the native blue crab, a commercially fished species on the Hudson, or other aquatic life. Despite the questions, some are already predicting what an invasion would look like: hairy-clawed crustaceans, tens of thousands of them, crawling into kitchens, infesting swimming pools and scampering across backyards. Such stories have been reported in Europe. "We have not been playing up the scary things, yet," Ferrante said. "It's wait and see."

Longtime crabber Bob Gabrielson Sr. is waiting, too, though he isn't holding his breath. It was his boat, piloted by his son, Bobby Jr., and Michael Frank, that hauled in the Hudson's first confirmed mitten crab this month. "The fact they will climb over dams, go on shore into people's swimming pools, burrow into banks, we sure as hell don't need them here," Gabrielson said. "I really believe there's not a damn thing in the world we can do about it." Boaters and anglers who come across the pesky crustacean are asked to contact the SERC Mitten Crab Hotline, at 443-482-2222, or via e-mail at sercmittencrab@si.edu. Specimens should be frozen or kept on ice.

Field guide to the Chinese mitten crab

Light-brown to olive in color, adult mitten crabs have two hairy claws with white tips. Their body, or carapace, is round and smooth and usually no larger than 4 inches wide. For protection and to avoid drying out, the mitten crab digs burrows into cliff banks above the low-tide mark. If less than 1-inch wide, mitten crabs might not have hairy claws, but can be identified by a distinct notch between the eyes.

Credit:By Greg Bruno