Overview: Aquatic Invasive Species in Alaska

tunicates on a brickA native tunicate, the clear sea grape Corella, and an introduced Botrylloides tunicate growing side by side on a brick in Ketchikan Harbor. Deborah Mercy/Alaska Sea Grant

Invasive species are non-native species whose introduction to an ecosystem causes, or is likely to cause, environmental damage, economic loss, and/or harm to human health. Alaska invasive species can be species that were introduced from outside the state, or are native to parts of the state but invasive when introduced elsewhere.

When a non-native species is introduced into a new ecosystem there may not be any natural predators, diseases, or other biological mechanisms to prevent that organism from spreading. Many species that are introduced into new environments are unable to survive, and many survive without having any negative effects on the ecosystem. The species that survive and cause significant negative effects are considered invasive species.

Invasive species can cause millions of dollars in damage to an ecosystem by changing the structure of the habitat, competing with native species for food and space, reducing or eliminating profitable fisheries, changing predator and prey interactions, and decreasing diversity and productivity.

Aquatic invasive species occur in oceans, streams, rivers, and lakes across the globe. Compared to the rest of the United States, Alaska has relatively few aquatic invasive species. However, changes in the climate and shipping traffic patterns are increasing the risk of invasive species. Growth in shipping traffic through the Arctic as a result of decreased sea ice cover increases the potential for invasive species to be introduced. Warming oceans, as a result of global climate change, will create environmental conditions more favorable for many introduced species that may not previously have survived in Alaska.

Once invasive species become established in an ecosystem, it can be challenging, and often impossible, to remove them. Preventing invasions is the best way to defend against the spread of invasive species. Catching invasions in their early stages is the most effective way to control them. As the risk of invasive species increases, Alaskans can be proactive to help prevent further invasions by taking steps to minimize the chances of invasion and by remaining vigilant and reporting all unusual plants and animals promptly.

How to Report Invasive Species

If you see any animal or plant that you think is unusual and may be an invasive species it is extremely important to report it. Alaska’s lengthy coastline and huge acreage of aquatic habitat make it exceptionally difficult for resource managers to monitor for invasive species. You can provide valuable assistance in monitoring by reporting anything unusual. Catching an invasion early is the best way to defend against the spread of these invaders and prevent ecological and economic damage.

Note the location with latitude and longitude, and take a picture if possible. If the organism in question is a plant or immobile animal, do not remove the organism. If the organism is a mobile animal, such as a green crab or Atlantic salmon, do not throw it back alive! Collect the animal, along with the location and date, and preserve it by freezing. Report your sighting to the Alaska Department of Fish and Game, Invasive Species Program, by emailing dfg.dsf.InvasiveSpecies@alaska.gov, or call the Invasive Species Hotline: 1-877-INVASIV (1-877-468-2748).

For More Information

Posters, flyers, factsheets and videos

Aquatic Invasive Species That May Be Found in Alaska


European Green Crab

How to Stop Invasive Species for...