The Latest on Aquatic Invasives

Zebra mussels on a southern Minnesota river. We don’t want them in Montana!

Aquatic invasive species—the subsurface threat to Montana’s waters, including our world famous fisheries and water-based recreation, was the theme of last month’s membership meeting of the George Grant Chapter of Trout Unlimited.

The threat of aquatic invasives has a lot of ramifications, such as the money needed to deal with invasive species, as well as damage to ecosystems, damage to fisheries and the way we do things in the outdoors.

Nicky Oullet, reporter for Montana Public Radio

Nicky Ouellet, the Flathead reporter for Montana Public Radio, had a special assignment to research aquatic invasives, particularly quagga and zebra mussels, and their effects. St. Paul, Minnesota, for example, is spending $150,000 yearly dealing with mussels in the lake where the city gets municipal water. Part of this includes daily scraping of filter screens to get rid of immature mussels that attach themselves to the screens.

People with lakeside property sometimes find that mussels have taken over their shorelines, and she interviewed a property owner who hauls out truckloads of mussels several times a year from his shoreline.

The mussels are native to Russia and came to the Great Lakes in ballast water of ships. The mussels apparently aren’t a problem in Russia, as they have their own set of predators in native waters. Once in the U.S., mussels often hitchhike on boats and boat trailers, as well as drifting downstream in river systems.

Once established, controls are difficult and expensive, including manual removal, such as what St. Paul does, along with some chemicals that have promise. The best strategy, however, is to avoid getting them in the first place.

Kate Wilson is an invasive species specialist for the Montana Department of Natural Resources, and recently started working in Montana after previous stints in Idaho, Florida, and Alberta, and discussed the State’s efforts.

Kate Wilson, aquatic invasives specialist, Montana DNRC

Invasive species became a critical issue in Montana a couple years ago when DNA evidence of invasive mussels was discovered in Canyon Ferry Reservoir and the Tiber Reservoir, the north central impoundment on the Marias River. Last year, the Legislature approved a surcharge on Montana fishing licenses to raise money for invasive species prevention.

The principal strategy is to inspect all boats and other watercraft when entering the state, as well as other inspections. People transporting watercraft from east to west of the Continental Divide must pass inspection before launching in western Montana waters. In 2017, inspectors found 17 boats coming into Montana that were carrying invasives.

Invasive mussels have become a huge problem in the Colorado river system in southwestern states, probably from snowbirds from Midwest and eastern states bringing mussels along with their boats.

Anglers can, just by themselves, spread invasives, and the best strategy is to thoroughly clean fishing gear such as waders and wading boots, especially felt-soled waders and boots. Yellowstone National Park recently announced a ban on felt-soled waders. Glacier National Park and the Blackfeet and Salish-Kootenai Nations already prohibit felt-soled waders.

An ongoing strategy is to educate boaters and floaters to clean, drain and dry boats when leaving a body of water. This means pulling drain plugs, wiping down boat hulls, removing any stray vegetation that’s clinging to boats or trailers.

If there’s some good news about invasives it’s that in spite of DNA evidence of invasive mussels in Canyon Ferry and Tiber reservoirs, there have been no findings of actual mussels.

While the bulk of attention has been directed toward quagga and zebra mussels, there are many other types of invasives that are problems. Some are invasive plants, such as Eurasian watermilfoil, an aquatic plant introduced for aquarium use, and later got introduced into other waters.

Then, of course, we have the infamous bucket biologists who intentionally move fish or other aquatic critters, such as crayfish, and stock them in new waters. Even common goldfish, members of the carp family, are a common problem.

In summary, aquatic invasives are a clear and present danger and anybody fishing or recreating on Montana waters needs to be careful and alert to avoid spreading non-native fish, plants, mussels, and other nuisances into our precious waters.

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