Scientists believe that green crabs , originally from Europe, reached U.S. shores in the mid-1800s after riding across the Atlantic in the ballast water on ships. Once here in North America, they travelled to Maine, where they have been present for more than a century. Green crabs are a non-native, or invasive species, organisms that have been transported via human activities and introduced to locations in which they previously did not occur. The green crab population in some areas of Maine has increased dramatically in recent years, and they have been feeding on shellfish resources such as blue mussels and soft-shell clams, threatening the state's third-largest wild fishery. The increase in the green crab population has coincided with an increase in ocean temperatures. A similar cycle occurred in the early 1950s when the ocean temperatures rose and the green crab population increased, devastating the soft-shell clam resource in Maine. What can be done to mitigate the environmental impact of this invasive species