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US Fish & Wildlife Service FieldNotes

STOCKTON FWO: Chinese Mitten Crab Workshop

Region 8, December 9, 2010
Chinese mitten crab. (California Department of Fish and Game photo).
Chinese mitten crab. (California Department of Fish and Game photo). - Photo Credit: n/a

By Jonathan Thompson, Stockton Fish and Wildlife Office

As the Pacific Southwest Regional Aquatic Invasive Species program staff have implemented the National Management Plan for the Chinese mitten crab (Genus Eriocheir) they have recognized the need to develop a National Workgroup to work on this problem. 

On November 1, a national workshop was held at the USFWS National Office in Arlington, Virginia.  The workshop was attended by the Mid-Atlantic and North East Panels on Aquatic Invasive Species, and numerous invasive species specialists from around the country and Mexico. 

The workshop goal was to establish a North American Chinese Mitten Crab Work Group, develop a network of East and West Coast activities, and identify future needs and the direction for national management plan for the mitten crabs.  

Thanks to the workshop, the newly formed workgroup will have monthly phone calls, an annual meeting, and begin updating the national management plan.

In Greek, the term eriocheir sinensis is literally translated as  “wool hand, the Chinese.” The Chinese mitten crab got its name because of the hair-like structures, or setae (hence the term “wool hand”), on its claws or cheliped. The crab is native to the South China Sea and its tributary rivers. The mitten crab is a catadromous species, which means that the adults spawn in the higher salinity waters of estuaries and their offspring migrate into freshwater to grow and mature. Once the crabs have reached sexual maturity, the adult crabs move downstream from their freshwater rivers and streams en masse and reproduce in the higher salinity waters of estuaries.

The Chinese mitten crab was first reported in the San Francisco Bay estuary in 1992, although it wasn’t until 1998 when the Chinese mitten crab received its 15 minutes of fame when water exports  had to be halted at the pumping facilities near Tracy, Calif. The pumping was halted because the crabs were so numerous that they severely impacting fish salvage activities.

Since 1998, the Chinese mitten crab population has not reached these epidemic proportions, but there are other potential impacts of this aquatic nuisance species’ presence, such as effects on recreational and commercial fishing.  The Chinese mitten crab is now being found with increasingly regularity in East Coast waterways.  The Smithsonian Environmental Research Center summarized the observations in May 2010.

 

“To date, there have been a total of one hundred forty-seven live Chinese Mitten Crabs (Eriocheir sinensis) reported and confirmed in the eastern United States. These crabs were found in Chesapeake Bay (2005-2007, 2009), Delaware Bay (2007, 2009-2010), Hudson River (2007-2010), and in New Jersey (2008-2010). In 2010 twenty Mitten Crabs have been captured in the lower Hudson River by crab dredging consisting”

Contact Info: Jonathan Thompson, (209)946-6400 ext315, jonathan_thompson@fws.gov