164 boats fail AIS inspections

Montana Fish, Wildlife and Parks aquatic invasive species specialist Linnaea Schroeer told the Flathead Lakers at their annual meeting that 164 boats failed to pass inspection in Montana so far this year, with standing water being the most common infraction.

“Public awareness of aquatic invasive species has never been higher,” she said, “but it seems that people are still forgetting to inspect, clean and dry their boats after use.”

Standing water can easily carry fish diseases, invasive mussel larvae and weed fragments, and it should be drained at the end of every trip.

“Also worrisome is the number of illegal live fish that crews have found,” Schroeer said. “Inspectors found eight people transporting live fish, which is illegal in Montana, except on roadways within the eastern fishing district. Lake Mary Ronan is the latest victim of illegal fish movement, as northern pike were found there this summer.”

Changing the behavior of boaters is the single most effective strategy for preventing introductions of zebra and quagga mussels and other aquatic invasive species, Alberta aquatic invasive species coordinator Kate Wilson told the Flathead Lakers.

Preventing transport of aquatic invasive species from areas where they have established to new areas is critical, and boats are the primary way zebra and quagga mussels are moved, Wilson said.

That means boaters can play a big role in preventing new introductions by remembering to clean, drain and dry their boats every time they take them out of the water.

Wilson previously worked on AIS prevention and control in Idaho and focused her master’s degree on engaging boaters and anglers in AIS prevention.

Zebra and quagga mussels aren’t the only aquatic invasive species that threaten Alberta and Montana, she said. Fish like the Asian carp and round gobi, plants like Eurasian watermilfoil and hydrilla, and crustaceans like the rusty crayfish could all wreak havoc on Montana waters if introduced, she said.

Zebra and quagga mussels are now present in nearby midwestern and southwestern states and were recently discovered in Lake Winnepeg, Manitoba.

“Basically any water body that doesn’t freeze solid is at risk,” Wilson said.

Among their many harmful impacts, exotic mussels filter enormous amounts of plankton out of the water and out compete native species, resulting in huge impacts to a lake’s food web and smaller and fewer fish. They also clog water treatment plants, drinking water systems, irrigation pipes and hydropower facilities.

If Alberta took no action to prevent introductions, Wilson said, aquatic invasive species could cost the province about $75 million per year in control and mitigation costs. The largest impacts would be on recreation, drinking water systems and property values. That makes a prevention program of $1 million per year a pretty good bargain, she said.

Manitoba recently treated four harbors on Lake Winnepeg with liquid potash, which appears to have been successful in suffocating the mussels. Containment barriers were used to close off the harbors from the rest of the lake.

There is no guarantee, however, that the tiny mussel larvae, or veligers, have not dispersed to other areas of the lake. One adult mussel can lay up to a million eggs a year. Treating the entire lake would likely be cost prohibitive, Wilson said.