The European green crab ranks among the world's worst invasive species — decimating populations of native clams, fish and other crabs. The voracious predators arrived in the U.S. from Europe in the 1800s, and today cost the East Coast fishing industry $19 million each year.
More recently, green crabs are threatening commercial fisheries in California.
KQED's Peter Arcuni takes a look at how ecologists in Marin County are striking back.
This segment aired on December 25, 2017.