Native range: Western Pacific Ocean from Russia to Hong Kong, Japan
Invasive range: Maine to North Carolina
Habitat: Intertidal. Often found in dense aggregations under rocks. Common on artificial mussel beds and oyster reefs.
Description: Adults are small, about an inch and a half in shell width. Square shell. Light and dark bands on legs.
The first sighting of the Asian shore crab in the United States was at Townsend Inlet, Cape May County, New Jersey, in 1988. Though the source is unknown, it is likely that the crabs were discharged as larvae from the ballast water of a cargo ship. The transfer of larvae around the world in ballast tanks is a form of “ocean roulette,” with each ship a potential chamber ready to discharge a new, unwanted species.
Along the Atlantic intertidal coastline from Maine to North Carolina, this crab is now breeding and increasing rapidly in number. Because it tolerates a wide range of environmental conditions, it seems all too likely to continue to multiply and to spread. Because it is not a picky eater, it outcompetes native species such as crabs, fish, and shellfish for food–-or it eats them, being an opportunistic omnivore that feeds on algae, saltmarsh grass, larval and juvenile fish, and small invertebrates such as amphipods, gastropods, bivalves, barnacles, and worms. Did we leave out anything smaller than a small crab’s mouth? That wide-ranging appetite and the growing population threaten both coastal ecosystems and aquaculture operations.
This invasive shore crab takes over habitats normally occupied by native mud crabs. It can compete with larger species, such as the blue crab, rock crab, lobster, and even another invader, the European green crab. The Asian shore crab breeds from May to September, twice as long as many native crabs. Females can produce 50,000 eggs per clutch, and 3 to 4 clutches per season. Suspended in tidal water for a month before developing into juvenile crabs, the larvae can be transported over great distances, a possible means of new introductions. And now tsunami debris from Japan has crossed the Pacific Ocean to Oregon and brought the Asian shore crab–-and lots of other species hanging on for the ride–-to the West coast of the United States for its first documented appearance.
Check under rocks and in tide pools at low tide. Read more on how to identify Asian shore crabs here.
Bun Lai, owner of Miya’s Sushi in New Haven, Connecticut, is one of the few chefs who proudly serves invasive species. His dish Kanibaba, which combines fried Asian shore crabs with sustainable sushi rolls, is designed to look like the craggy seashore home of these tiny invaders.
Below is one of Lai’s simple recipes.
Asian Crab Popcorn
Collect about 30 small Asian shore crabs
Olive oil for frying
Chile pepper to taste
Old Bay Seasoning
In a large pan, heat oil for frying.
Submerge the crabs in oil. (Be careful with splatter.) Add chile pepper to the oil. The crabs will turn a beautiful orange as they cook, and are done when they are no longer releasing water: about 15 minutes.
Remove the crabs from the oil with a slotted spoon and place on paper towels to drain.
Squeeze lime and then sprinkle Old Bay Seasoning over the crabs.
Serve while hot.
For a demonstration, see this video from ABC News.
And here’s Bun, no holds barred, on Connecticut Style.
Sawagani on Grilled Pineapple Salsa with Tabasco
The folks at Tabasco have developed a recipe for Asian shore crabs, or sawagani, which can be found on their website here.
E. A. McIlhenny, who branded the sauce, also helped establish the invasive nutria in New Orleans, in an attempt to bolster the local fur industry.
Asian Shore Crabs in Coconut Milk, Filipino style
Adapted from Panlasang Pinoy Recipes.
Approximately 25 Asian shore crabs
8 to 10 taro leaves with stalks, shredded and wilted (available in many Asian markets)
4 to 5 green peppers (jalapeño or Thai)
5 to 6 cloves of garlic, minced
2 tbsp. minced ginger
1 can coconut milk (coconut cream can also be prepared)
1 medium onion, minced
salt to taste
Wash shore crabs and drain.
In a large pan, sauté garlic, ginger, onion, and green peppers, in olive oil.
Add coconut milk.
When milk boils, add taro leaves and stalks. Simmer for about 30 minutes.
Add crabs. Cook until sauce thickens.