CoastWise Alaska

Invasive Species

Length with intro/outro: 3:11

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Alaska's coastal waters can be an inhospitable home for marine creatures not accustomed to icy cold water. But some nonnative species are slowly finding the place to their liking. This week's CoastWise Alaska joins the hunt for marine invasive species making their way up the coast.


Several times each year, Gary Freitag and a pilot friend fly from Ketchikan to remote Dall Island on the Alaska-Canada border—a distance of about 80 miles. They make the trip to look for illegal aliens.

European green crabThey’re not the U.S. Border Patrol looking for people sneaking into the country. Freitag is a biologist with the Alaska Sea Grant Marine Advisory Program at the University of Alaska Fairbanks. He goes to Dall Island to look for European green crabs that might make their way north from British Columbia.

FREITAG: “It’s the most southern island on the outside coast. And I’ve got an inlet there that I can land in with a floatplane. We fly out and we set pots—traps, basically—in that estuary that has sea grass and has Dungeness (crabs) in it, and it’s the right kind of conditions—and we set pots there overnight and fly back out the next day and check them.”

European green crabs are considered an invasive species—that’s a species not native to the region, and one that can displace native plants and animals and cause serious environmental damage. So far, the crab has made its way as far north as British Columbia. And though the crabs are just a few inches in size, Freitag says the crab’s arrival would be bad news for Southeast Alaska’s crab fisheries and the region’s marine ecosystem.

FREITAG: “First of all, they are a fairly aggressive crab. When you have a lot of these green crab they can actually be pretty competitive, if not kill a lot of the indigenous species. The other problem is that they are really, really devastating on shellfish. A lot of the resources that depend on mussels and clams are getting impacted because theses guys are eating a lot of the food. They’re quite nasty little critters.”

So far, Freitag hasn’t caught any European green crabs at Dall Island. But he thinks it’s just a matter of time before he does.

FREITAG: “Yeah, it’s probably going to establish. The environmental conditions in Alaska are ideal for this animal."

A few years ago, researchers from the Smithsonian identified other invasive species that have made their way to Alaska—two species of invasive tunicates, commonly called sea squirts. Thought to have first come into the United States from Japan in the 1970s, they look a bit like an orange-colored sponge. Colonies of invasive tunicates have been found in several places around southern Southeast Alaska. Freitag says their spread poses a special danger to the region’s shellfish aquaculture farms.

FREITAG: “There are people raising oysters up here in Alaska, which is happening pretty heavily over on Prince of Wales, Metlakatla, and areas like that. They can actually smother the cages and cause disruption of water flow and oxygen flow.”

When it comes to spotting illegal aliens, Freitag has his work cut out for him. He’s one of just a handful of people looking for invasive species along Alaska’s thousands of miles of coast.


CoastWise Alaska is a production of the Alaska Sea Grant College Program, University of Alaska Fairbanks, which offers outreach and technical assistance to help Alaskans wisely use, conserve, and enjoy the state's marine and coastal resources. Check out our Web site at

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