In areas where green crab have been able to establish reproducing populations, they have had dramatic impacts on other species, particularly smaller shore crab, clams, and small oysters. While green crab cannot crack the shell of a mature oyster, they can prey upon young oysters, and will dig down six inche… Although the European green crab has successfully spread to various locatio… The crab had spread to the north all the way along the coast of Maine and up into Nova Scotia by the mid-1900s. Green crabs are believed to have caused the collapse of the soft-shell clam industry in New England. Covering commercial shellfish with anti-crab nets can also effectively keep the crabs out (Feal and Kraus 2002). However, the best way to stop an invasion like the European green crab is to prevent it from happening in the first place, which could be achieved with more detailed inspections of ship ballasts before they depart and arrive at ports. By the 1980s, the crab had reached San Francisco Bay and started to spread along the west coast, and in 1996, the crab inhabited over 500 km in California. The European green crab eats smaller crustaceans and many other plants and animals, and can have dramatic negative impacts to native shore crab, clam, and oyster populations. The Quiet Invasion: A Guide to Invasive Species of the Galveston Bay Area - European Green Crab, Mediterranean Green Crab Texas Commission on Environmental Quality, Galveston Bay Estuary Program; Houston Advanced Research Center (HARC). Their digging habits also have slowed eelgrass restoration efforts. This marine predator was thought to have been introduced to the U.S. Atlantic coast in 1817. Green crab pose a threat to Washington's native shellfish, which are important for recreational and commercial harvest as well as to the shellfish aquaculture industry, and native estuary ecosystems.