Invasive green crab species detected in Alaska for first time

ANCHORAGE, Alaska (KTUU) - For the first time as far as records show, green crabs have been reported in Alaska waters, according to the National Oceanic and Atmospheric Administration.

The organization said in a release that the Metlakatla Indian Community first discovered the species on July 19, 2022, when three crab shells were found during a survey on the Annette Islands Reserve.

Dozens more have been discovered since then, according to NOAA, from Tamgas Harbor to Smugglers Cove.

Green crabs have some special features that make them stand out, according to Tammy Davis with the Alaska Department of Fish and Game.

“They aren’t necessarily green,” Davis said. “They can be green, brown, yellowish, orange, red, and there are a lot of other factors that contribute to that.”

Davis said there are some easy ways to distinguish green crabs from other crab species.

“They have five spines on the outside of their eyes ... that go around the edges of their carapace, or the shell,” Davis said. “Those are really good indicators of green crabs. No other crabs in Alaska have those five spines. They also have three bumps between the eyes that are pretty characteristic, but the five spines are dead on.”

Despite NOAA surveys that span years, this is the first time green crabs have been discovered in Alaska. So far, scientists know of at least 56 green crabs that have been detected on Annette Island in Southeast Alaska.

The species is a threat to native species and habitats. Both adult and juvenile green crabs can disrupt eel grass meadows and beds — eel grass is important for juvenile Dungeness crabs and serves as a nursery for juvenile Pacific salmon.

“Destruction of those beds could have both physical changes to our coastal environments, but also when those eel grass beds are damaged, the food webs for a variety, that whole community is damaged,” Davis said.

Although invasive species are difficult to address, the Department of Fish and Game says there’s still something people can do.

“We ask people to take a picture, take multiple pictures, snap pictures from the top, the side, the bottom, get as many pictures of the organism as you can,” she said. “Maybe include a credit card or a cell phone to show size and scale.”

Davis added that it’s important to never collect or move any species around, regardless of the environment.

Photos of suspected green crabs can be sent to the Alaska Department of Fish and Game. There is also an invasive species hotline at 1-877-INVASIV (468-2748).

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