Invasive Species

Crabby about Invasive Green Crabs

Alaska feels the pinch for the first time

A person holds a European Green Crab in their hand. The crab has one pincher in the air.
Say hello to my little friend. 📸 Ryan Munes, USFWS

Hungry little crabs with a big impact

The carapace, or shell, of a European green crab alongside a full green crab. The green crab has 5 distinct spines on either side of the eyes.
Invasive green crab carapace and a whole live crab. 📸 Linda Shaw, NOAA
  • Juvenile salmon and other fish as nursery habitat.
  • Herring and other fish as spawning habitat.
  • Bivalves, such as clams and mussels, and crustaceans as sediment habitat.
  • Migratory and resident shorebirds and sea ducks as foraging habitat.
  • Marine mammals, such as sea otters, as foraging habitat for prey.
Bright green eelgrass beds line the shore of a coastal beach.
Eelgrass beds of Colby Creek Estuary. 📸 Linda Shaw, NOAA

A crabby welcome to Alaska

A person on a boat holds a trap used to catch European green crabs.
Researcher pulling a shrimp pot used to trap invasive green crabs. 📸 Linda Shaw, NOAA

Learn to identify this critter 🦀

  • Report any green crab sighting. If you’re on Annette Islands Reserve, call (907) 886-FISH. If you’re anywhere else in Alaska, report it to Alaska Department of Fish and Game’s online Alaska Invasive Species Reporter or the Invasive Species Hotline at (877) INVASIV. Don’t keep or kill the crab, but rather take plenty of photos- along with a standard size reference item, such as a coin or key. Then, send your photos to the Alaska Department of Fish and Game (
  • If you’re interested in getting your hands wet and dirty, you can volunteer to be a citizen scientist by joining the marine invasive species citizen monitoring network. Contact ADF&G Invasive Species Program coordinator at 1–877-INVASIV to get involved!
  • If you’re beachcombing, keep an eye out for carapaces while strolling the coast. The carapace, the hard upper shell of a crab, is shed during molting. Looking for carapaces is a great way to detect the presence of invasive green crab, as well as other native species. Not only is it a fun treasure hunt, but you are helping to track and detect invasive species! Just make sure to count the spines — remember five behind the eyes = invasive!
A volunteer holds a green crab next to a sign asking people to keep an eye out for the animal.
Volunteer holding a crab carapace. 📸 Linda Shaw, NOAA



Stories from Alaska by the U.S. Fish & Wildlife Service

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