Blue crabs are showing up in Maine waters. What could that mean for green crabs?

Blue crabs are increasingly being spotted in Maine waters, raising questions about how the invasive species could affect the Gulf of Maine’s longstanding green crab problem. Green crabs—introduced from Europe about a century ago—have damaged eelgrass habitats and preyed on soft-shell clams, harming fisheries and ecosystems. Fishermen have noticed blue crabs in recent years as the Gulf of Maine warms and allows the mid-Atlantic native species to move north. Researchers at the Wells National Estuarine Research Reserve and Bowdoin College, publishing in the Journal of Experimental Marine Biology and Ecology, found larger blue crabs kill and eat smaller green crabs. Bowdoin biology student Reuben Siegel set traps in Harpswell and the New Meadows River, then used tanks to observe interactions over 24 and 48 hours, with predation occurring in about half the trials.