Chinese Mitten Crab Caught In Chesapeake Waters 
(report: August 2006)

While fishing his crab pots in early June, a Chesapeake Bay waterman hauled in an unusual catch at the mouth of the Patapsco River, a mature male Chinese Mitten Crab Eriocheir sinensis. It was the first time anyone had ever reported finding a Mitten Crab in Bay waters. Native to East Asia, the crab is significant as a potentially harmful invasive species that has caused economic damage in Europe and on the West Coast of the U.S. 

Recognizing his catch as unusual, the waterman held on to the crab in his freezer, reported it as a possible Mitten Crab, and later presented it to Maryland Department of Natural Resources (DNR) for confirmation. The crab was then brought to the SERC where invasive species expert Greg Ruiz, crab expert Tuck Hines and Chinese visiting scientist Yongxu Cheng who studies the Chinese Mitten Crab examined the specimen.

Yongxu Cheng, an expert in Chinese Mitten Crab biology and SERC visiting scientist discusses the specimen with (left to Right) SERC scientist Whitman Miller, Lynn Fegley of MD DNR, and SERC scientists Tuck Hines and Greg Ruiz.

There are several possible ways the crab could have arrived in Bay waters, including imported seafood trade or commercial shipping in near-by Baltimore Harbor.

Because only a single mitten crab was captured, this may be an isolated occurrence and does not indicate that the species is established here. None-the-less, the Chinese Mitten Crab is known to be a successful invader capable of establishing itself in new areas and causing harm. For this reason, the crab is listed under the Federal Lacey Act which makes it illegal to possess (import, export, transport, sell, receive, acquire or purchase) this species in the United States.

So the experts are taking it seriously. DNR, SERC, the U.S. Fish and Wildlife Service, and the National Oceanographic and Atmospheric Agency have established a joint effort to investigate the status of mitten crabs in the Bay and to notify other agencies to be on the watch for Mitten Crabs. http://www.dnr.state.md.us/dnrnews/infocus/mitten_crab.asp

The Chinese Mitten Crab is catadromous, meaning it lives in both salt and fresh waters during different phases of its lifecycle. Young crabs spend two to five years in freshwater tributaries and can extend over 50 miles inland, potentially above fall lines. Mature male and female crabs migrate downstream to mate and spawn in salt water estuaries.

The single captured crab is being examined in greater detail in collaboration with the Smithsonian’s National Museum of Natural History, where it will be catalogued and entered into the national collection.

Direct questions to: Dr. Greg Ruiz at SERC (443-482-2227) or Lynn Fegley at MD DNR, fisheries service (410-260-8285).

To Learn More About Mitten Crabs See:

http://invasions.si.edu/nemesis/CH-TAX.jsp?Species_name=Eriocheir+sinensis View the listing for Mitten Crab in the SERC NEMESIS database. National Exotic Marine and Estuarine Species Information System (NEMESIS) is a resource for information on non-native, or exotic, species that occur in coastal marine waters of the United States.

First records of Eriocheir sinensis H. Milne Edwards, 1853 (Crustacea, Brachyura: Varunidae) for Chesapeake Bay and the mid-Alantic coast of North America.   See the research article published in the journal Aquatic Invasions on the Mitten Crabs found in the Chesapeake Bay. 

http://www.dnr.state.md.us/dnrnews/infocus/mitten_crab.asp DNR's watch details how to identify a mitten crab and what to do if one is caught.  

http://www.wsg.washington.edu/outreach/mas/nis/mittencrab.html