Chinese mitten crab (California and New Jersey)

The Chinese mitten crab is native to Southeast Asia but was introduced to California in the early 1990s, probably by way of international ship travel. It is now established throughout many California water networks surrounding the San Francisco Bay, and also in New Jersey, with several other states reporting sightings. The crabs are edible, and considered a delicacy in some cultures. They are imported live, sometimes illegally, as the sale of these crabs is prohibited in certain states. Release of live crabs from these shipments may be another means of introduction. Ecologically speaking, Chinese mitten crabs are a nuisance in non-native areas, especially in urban areas, and may clog water pumps and hamper water delivery. They also burrow into soil, which can exacerbate riverbank erosion and weaken levees. The mitten crab eats a variety of plant and animal materials, which may harm recovery efforts of endangered species in the California delta; they are also a problem for rice farmers, as the crabs can damage the rice crop in flooded fields by eating young shoots. Although there is limited data, testing on Chinese mitten crab captured in California has revealed low levels of chemical contaminants; there is little data on New Jersey populations of this species.