Press Release
U.S. Fish and Wildlife Service Cracks Down on the Illegal Mitten Crab Trade

U.S. Fish and Wildlife Service wildlife inspectors have prevented the illegal and potentially harmful import into the United States of approximately 15,000 live Chinese mitten crabs as part of the law enforcement operation codenamed Hidden Mitten.

Chinese mitten crabs are one of North America’s most invasive species invasive species
An invasive species is any plant or animal that has spread or been introduced into a new area where they are, or could, cause harm to the environment, economy, or human, animal, or plant health. Their unwelcome presence can destroy ecosystems and cost millions of dollars.

Learn more about invasive species
and pose a serious threat to humans and the environment. In high densities they can cause a number of problems. The crabs may outcompete native species for food and space; undermine flood levees and cause stream bank erosion; clog screens, pumps and water intake structures at fish collection facilities and power plants; and hurt commercial and recreational fishing industries by consuming bait, damaging fishing nets and devouring catch.

The species is also a carrier of Oriental lung fluke, a parasitic disease that can be transferred to humans in raw or undercooked crab meat. Fortunately, the Service works with specialists who test seized species for disease, and the fluke has not yet been found in mitten crabs collected within the United States.

Mitten crabs are considered a culinary delicacy in Asia and are smuggled into the United States in mass quantities in preparation for Chinese New Year and other cultural events. Recent studies estimate that the economic cost of combating invasive species in the United States is approximately $120 billion per year.

With the assistance of U.S. Customs and Border Protection (CBP), Service wildlife inspectors seized the crabs at U.S. express hubs and major international airports. Smugglers had falsely declared the shipments as t-shirts, jeans, auto part samples, shopping bags, photo albums and other commercial products.

“The U.S. Department of the Interior is committed to protecting our nation’s natural resources for the continued benefit of the American people. Chinese mitten crabs pose a significant threat to humans, the environment and our economy,” said Rob Wallace, Assistant Secretary for Fish and Wildlife and Parks at the U.S. Department of the Interior. “I would like to thank the U.S. Fish and Wildlife Service Office of Law Enforcement and U.S. Customs and Border Protection for their assistance with this operation. Together, we can help protect our nation from invasive species while combating the illegal wildlife trade.”  

“Our agriculture specialists and officers work closely with other federal agencies to protect our natural resources,” said CBP Supervisory Agriculture Specialist Barbara Hassan. “In this case, cooperative efforts with the U.S. Fish and Wildlife Service prevented the introduction of a highly invasive and destructive species into our ecosystem.”

In the United States, mitten crabs have already spread to several California waterways, the Chesapeake and Delaware bays, and the Hudson River. The crabs were introduced either intentionally to create a future food supply or accidentally through the discharge of contaminated ship ballast water. Once introduced to a new location, the crabs can spread rapidly. Female mitten crabs are capable of producing 100,000 - 1,000,000 eggs per brood and crabs can migrate up to 11 miles per day.

Operation Hidden Mitten was the first international inspection operation initiated by the newly formed U.S. Fish and Wildlife Service Wildlife Inspection Interdiction Team. The team consists of seasoned Service law enforcement professionals who are committed to closing international wildlife trafficking pathways, generating intelligence and coordinating national wildlife inspection efforts. 

Under the Lacey Act, it is illegal to import mitten crabs and other injurious wildlife without a permit.

If you suspect someone is illegally importing mitten crabs or any other species, please call the Service’s wildlife trafficking tips line at 1-844-FWS-TIPS (397-8477) or email You might be eligible for a financial reward if your tip helps solve a case.

You can help protect native ecosystems from mitten crabs, and other aquatic invaders, by:

  • Cleaning your boat and all of your gear (including waders and boots) after each use.
  • Draining all of the water from your boat before leaving the area.
  • Drying your gear completely (at least 48 hours) after each use.

More information regarding this species is available here: