Field Notes
U.S. Fish & Wildlife Service
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ALASKA FISHERIES: Aquatic invasives species in Alaska near a tipping point?
Alaska Region, May 28, 2014
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A float plane taking off from Sand Lake in Anchorage, one of 14 waterbodies in Alaska known to be infested with Elodea to date.
A float plane taking off from Sand Lake in Anchorage, one of 14 waterbodies in Alaska known to be infested with Elodea to date. - Photo Credit: USFWS/Cecil Rich

Alaska may be unique in a lot of ways, but not when it comes to being acutely vulnerable to invasive species. Invasives from around the world have a growing presence across the Alaska landscape—and they’re changing it, threatening the very character that makes Alaska special.

For example, Elodea, Alaska’s first known aquatic invasive plant, has already invaded three of Alaska’s foremost salmon areas: the Copper River region, the Kenai Peninsula, and Chena River (a major Chinook salmon producer in interior Alaska). What’s at stake? Alaska’s freshwater fish habitat and fish—Elodea’s already been documented choking out Chinook salmon and Arctic grayling spawning and nursery habitat.

A popular aquarium plant and teaching specimen in Alaska, Elodea was likely introduced via the dumping of a home or school aquarium. It spreads easily, with even small fragments being able to establish new populations after hitching a ride on boats, trailers, floatplanes, or simply being carried downstream. This invader—having also taken root in several Anchorage lakes only a short distance from Lake Hood (the world’s busiest floatplane base that serves much of the state)—is only one flight away from its next invasion.

Invasives have more potential pathways into Alaska than ever before, and even more paths are poised to open up as a result of climate change. For example, loss of sea ice is projected to greatly expand northern shipping activity, increasing risks of shipping-assisted species invasions into Arctic and Bering Sea coastal waters. Increased oil and gas development in Arctic waters will likewise bring drilling rigs that have the potential to unintentionally transport invasive species.

A changing climate is also helping some invasives move northward. For example, the European green crab (an invasive that’s already established itself along Canada’s west coast and competes with commercially-important native crab species) is expanding its range northward along the British Columbia coast as coastal waters warm.

Invasives pose a threat to Alaska’s fisheries, and its coastal economy. For example, the invasive colonial tunicate Didemnum vexillum was discovered in a Southeast Alaska harbor in 2010.

This species threatens to foul marine areas in Alaska (including bottom habitats, shellfish aquaculture areas, maritime structures) as it has in many areas along the west and east coasts. For example, off the coast of New England, in Georges Bank, it’s already formed dense mats over hundreds of square miles of groundfish and scallop habitat. There’s great concern that this species will continue to spread in Alaska, impacting regionally-important subsistence and commercial fisheries such as Pacific herring that are so important to coastal communities.

Documenting and rapidly responding to invasions in Alaska poses a unique challenge given the state’s size, its complex and lengthy coastline (Alaska has more than half of the total U.S. coastline), the extremely large number of water bodies compared to other states, and the relative lack of human capital and manpower to detect and respond to new invasions.

Despite this, Alaska does have one unique advantage: invasions are still somewhat contained. Thus the opportunity still exists to avoid the crippling economic impacts and habitat losses resulting from new species invasions. Annually—in the contiguous United States—aquatic invasive species alone already cost tens of billions of dollars in damages and control efforts.

Effectively responding to invasive species in Alaska requires prevention and a readiness for rapid response when they arrive—whether by herbicide to rid a lake of Elodea or removal of marine structures fouled by invasive tunicates. To get there, we all need to be informed about how invasives enter Alaska and spread. The State of Alaska, the Service, and a growing number of other partners are working together, and with the public, to keep aquatic invasives at bay.

First published in Alaska Fisheries and Habitat News Spring 2014
Contact Info: Katrina Mueller, 907-786-3637, katrina_mueller@fws.gov
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