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Aquatic invader threatens Alaska lakes, salmon, floatplane traffic

  • Author: Tobias Schwoerer
  • Updated: May 8
  • Published May 8
 
Canadian waterweed, Elodea canadensis (with enlarged cross section of a single whorl). In this instance, the leaves are relatively long and narrow (four times longer than wide). (Photo by Christian Fischer / Creative Commons)

Invasive plants and animals are gaining a foothold in Alaska. They are slowly but relentlessly changing our environment and economy — changes that most people are unlikely to notice because they occur over long periods.

In other parts of the world, invasive species have already damaged the environment, harmed human health and caused significant economic losses. Alaska, by contrast, had relatively few biological invaders for most of the 20th century.

But things have changed. Alaska now has many invasions in their initial stages. The most threatening right now is elodea, a freshwater aquatic plant.

Elodea is commonly used for vegetation in aquariums, and it is likely that people emptying their aquariums into Alaska's waterways triggered the invasion. First discovered in waters near residential areas and or elementary schools in Alaska towns, elodea spread rapidly in slow-moving water or ponds.

In Interior Alaska, it is being carried downstream from Chena Slough into the watersheds of the Tanana and Yukon rivers. Throughout the state, floatplanes are inadvertently spreading it to remote water bodies, when fragments of the plant get caught on floatplane rudder assemblies.

Today we are at a critical point. Ridding Alaska of elodea is still possible. Government agencies have already removed elodea from 12 lakes — more than half the 20 known infested waterways — without risking other aquatic resources or native vegetation. But if we do not remove all known infestations now — and set up a system to efficiently deal with any new elodea infestations — we'll face long-term management costs and damage to fisheries, tourism and subsistence resources.

If elodea spreads further, it will likely reduce salmon spawning and rearing habitat and compromise the long-term health of Alaska's salmon stocks.

How much would insufficient action cost Alaskans?

I recently estimated the full range of potential ecological and economic effects of elodea on Alaska's commercial sockeye fisheries by combining fisheries market data with what experts believe elodea could do to sockeye salmon.

A statewide survey of floatplane pilots showed where elodea is most likely to be spread. I also calculated the cost to floatplane pilots of losing access to landing sites because dense aquatic vegetation endangers floatplanes as they take off or land.

If elodea spreads throughout Alaska, between 200 and 300 floatplane lakes could be infested with elodea by 2030. The economic loss to commercial sockeye fisheries and recreational floatplane pilots would most likely approach $97 million a year — or about a quarter of the value fishermen received for their 2016 Alaska salmon catch.

Alaska floatplane traffic

To prevent these losses, Alaska would need both to finish cleaning up known infestations and put in place an emergency response system to deal with new, previously unknown, elodea infestations. Critical to an emergency response system are funding, coordination and streamlined permitting.

So far, successful elodea cleanups have largely been funded by the U.S. Fish and Wildlife Service. The formal establishment and funding of a rapid response fund — such funds exist in several other states — would set aside emergency funds for managing previously unknown elodea infestations and dealing with newly discovered invasive species that would be far more damaging than elodea. For example, another aquatic invasive plant — Eurasian watermilfoil — has not yet been found in Alaska yet, but it's ranked at the top of Alaska's list of invasive plant threats.

Critical for statewide coordination and permitting efforts are a small number of dedicated employees in the state Division of Agriculture and the departments of Fish and Game and Environmental Conservation. Coordination has shortened the permitting window to a minimum of 100 days. Further streamlining would allow treatment to occur when environmental conditions are ideal for achieving highest clean-up success. Also, due to elodea's explosive growth, any cleanup delay can lead to further spread and higher cleanup costs.

I estimate that a one-time investment of approximately $10 million could clean up all known elodea infestations Alaska. That doesn't include the cost of monitoring nor the cost of cleaning up new infestations that come to light later.

In light of the economic and cultural importance of salmon in Alaska, and compared with estimated future costs, these investments likely yield a very high return, even in a time of declining budgets.

Tobias (Toby) Schwoerer is a senior research economist at UAA's Institute of Social and Economic Research. He recently received a Ph.D. in bioeconomics for his research on the potential economic consequences to commercial salmon fisheries and floatplane pilots from elodea. The research was primarily funded by the Alaska Sustainable Salmon Fund and Alaska SeaGrant and was conducted in collaboration with state and federal agencies. The opinions are his, not those of ISER or UAA.

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