Although the source of introduction for mitten crabs to US Atlantic Coast (NEMESIS 2011) estuaries is uncertain, there are two plausible transfer mechanisms to the region, including the release of live seafood and discharge of ships’ ballast water.
Mitten crabs are a popular food in many Asian countries. Even though it is now illegal to import this species alive to the US, it is possible that imports and release occurred in the past, resulting in this invasion.
Alternatively, ships can transfer crabs and their larvae in ballast tanks, which are frequently discharged in subsequent ports of call. The mid-Atlantic US and San Francisco Bay, where mitten crabs have been found, both receive ballast water discharge from foreign ports where the crab is known to occur.
For more on ballast water, please visit NBIC: National Ballast Information Clearinghouse.
Shipping - ballast water
Fisheries - Accidental or intentional release of live seafood
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| Fishermen sorting crabs. | Bundles of live mitten crabs being sold in a market in Daejeon, South Korea. |