Invasive green crab have arrived in Alaska

Image of European green crab with graphic showing how to identify a green crab. The image demonstrates that the crab can be identified by counting the spines and bumps along the front edge of the shell. There are three rostral bumps in the middle, with one eye bump on the outside of the rostral bumps, followed by five spine bumps on each side next to each eye.
Invasive European green crab, or Carcinus maenus, can be identified by counting the spines and bumps along the front edge of the carapace (shell). There are three rostral bumps in the middle, with one eye bump on the outside of the rostral bumps, followed by five spine bumps on each side next to each eye. The carapace is up to 10 cm/3.5 inches from front to back and side to side.

In July 2022, Metlakatla Indian Community found the first evidence of invasive European green crab (ECG) when a shell was found along the shoreline during regular monitoring at the Annette Islands Reserve.

As of fall of 2022, hundreds of live crabs had been trapped at this location, which is less than 700 miles from Prince William Sound.

Update June 2024 – ECG found at Gravina Island: Invasive European Green Crab Confirmed in Alaska (ADF&G media release)

This species is of particular concern because the crabs negatively impact shellfish, important habitat for juvenile salmon and native crabs, and other marine resources. Invasive green crab have destroyed habitats and outcompeted local species in other locations.

Since 1996, the Council has studied marine invasive species, such as European green crab. Research on these crabs has shown:

  • They can survive in conditions found in Prince William Sound. A warming climate makes an even more suitable habitat.
  • Invasive crab larvae could survive in the ballast water of an oil tanker, bringing them to our region from infested waters.
Poster with details about how to identify a european green crab. These can be identified by the five distinct spines, or bumps, on each side of the eyes at the front of the shell. Details on how to report a European green crab can be found at the link in the caption for this image.
Information flyer from Alaska Department of Fish and Game. Report a suspect crab via the ADF&G Online Reporter or call 1(877)INVASIV.

What can you do?

  • Support legislation: Contact your legislator to voice your support for a coordinated response to invasive species in Alaska.
  • Search and report sightings: Look for invasive crabs on beaches, alive or dead. Do not collect the crabs. Take photos and report sightings to the Alaska Department of Fish and Game (ADF&G).
  • Set up traps through ADF&G: Join the Alaska community-based Early Detection Monitoring Network to set traps in your community. Contact ADF&G to find out more: 1(877)INVASIV

What to do if you see a suspected invasive green crab

  1. Take multiple photos of the live crab or crab shell. Collection and transport is prohibited.
  2. Note the number of crabs, the location (GPS coordinates or landmarks), and type of habitat.
  3. Report online or call the ADF&G Invasive Species Hotline: 1(877)INVASIV.

More information:

 

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