BioStation Report: Prevention Efforts Keep Invasive Mussels In Check, But Collaboration is Key

Nearly 100,000 boats were inspected this year, resulting in the discovery of 53 mussel-infested watercraft; however, researchers credit partnerships among a multitude of state, federal and tribal stakeholders with keeping the Flathead Basin mussel-free

By Tristan Scott
Erik Hanson, invasive species consultant with the Flathead Basin Commission, cleans a boat that was contaminated with aquatic invasive mussels on April 5, 2016. Greg Lindstrom | Flathead Beacon

If the whole is greater than the sum of its parts, as the Aristotelian aphorism has us believe, then the coordinated efforts by a wide range of Montana stakeholders determined to keep aquatic invasive species at bay are worth their weight in gold.

That’s according to researchers with the Flathead Lake Biological Station’s (FLBS) Aquatic Invasive Species (AIS) program, who credit the collaboration of agency managers and community leaders with halting the spread of invasive mussels in their tracks. 

“Although we have found evidence of AIS spreading in the Flathead Basin, such as flowering rush and curly leaf pondweed, we have not detected the presence of zebra or quagga mussels yet, which are by far the most detrimental of the threats,” said FLBS AIS Specialist Phil Matson, who added that Montana’s rapid response in 2016 was also key to preventing a full-blown invasion. “However, this does not mean we can let our guard down.”

Six years ago, one of the most devastating invasive species in the world arrived at the gateway to the Flathead Basin, posing ecological and economic consequences that could imperil the pristine watershed in perpetuity. On Nov. 8, 2016, the discovery of destructive mussel larvae in Tiber and Canyon Ferry reservoirs east of the Continental Divide signaled the first time the aquatic invasive species had been detected in Montana waters, pulling a hypothetical scenario into dire focus.

An infestation of zebra or quagga mussels could spell the beginning of the end for Montana’s most pristine watersheds, experts say, holding the potential to topple underwater food webs that prop up the Treasure State’s prized aquatic species while wreaking havoc on its infrastructure and recreation economy.

“This is a huge deal. We have been bracing ourselves for this for a long time and hoped it would never happen,” Tom Bansak, assistant director of the Flathead Lake Biological Station, said at the time. “Well, it’s here, it’s now, it’s real, and the only possible chance of getting rid of them is finding them early and in a localized area.”

To aid in the continued coordination of statewide resources to prevent invasive mussels from spreading across Montana’s waterbodies, a legion of state, tribal, federal, and local watercraft inspectors checked nearly 100,000 boats in 2022 alone, intercepting 53 mussel-infested watercrafts. 

In the past year, aquatic ecologists at the FLBS completed four rounds of early detection sampling for invasive zebra and quagga mussels around Flathead Lake. Made possible by grant support from the Montana Department of Natural Resources and Conservation (DNRC) and the FLBS’ philanthropic community, the efforts resulted in nearly 700 collected samples at Flathead Lake in 2022.

All samples collected by FLBS have either already been processed or are currently being analyzed and, to date, none have tested positive for the presence of invasive mussel DNA, which agency officials hail as an ecologic and economic success.

Matson emphasized that, while AIS boat inspections have filtered out the threat from out-of-state boaters, Montana remains extremely fortunate that a mussel-infested boat hasn’t slipped through any chinks in its armor. He also stated that continued collaboration is vital to the long-term success of Montana’s invasive mussel prevention, because one misstep could have longterm consequences.

“Over the last several years, the State of Montana has recognized the importance of partnerships to combat the spread of AIS and has provided funding and support to keep programs strong and effective,” Matson said. “Whether it be boat inspections, year-round monitoring, or education outreach, the state cannot do it alone.” 

In addition to boat inspections, sampling, and monitoring, there are two other key areas that are crucial to FLBS, statewide, and regional AIS prevention efforts, Matson said.

The first is ensuring that the sampling process is yielding the most accurate results possible. Having secured the DNRC grant last year, Matson and FLBS graduate student Leif Howard began working to optimize the decontamination protocol for environmental DNA, or eDNA, sampling gear to minimize the potential for false results and eliminate uncertainties regarding AIS detection sensitivity.

Because eDNA can be found in water year-round, its use in early detection monitoring provides an opportunity to detect mussels well before the standard monitoring technique of microscopy, Matson said, which can only be used during a brief window in summer when mussels are spawning — at which point they have already become well established.

“By then it might be too late,” Matson said. “Being able to detect mussels with eDNA before they spawn widens the optimal response window.”

The second key to successful AIS prevention is community education and outreach, Matson said. FLBS is in its sixth consecutive year partnering with the Confederated Salish and Kootenai Tribes (CSKT) and works closely with Montana Fish, Wildlife and Parks (FWP). The FLBS researchers interacted with more than 150 members of the general public during sampling along the shores of Flathead Lake, Matson said, allowing scientists to field questions about what AIS sampling crews are looking for and explain the “Clean, Drain, Dry” campaign that has been pivotal in the state’s messaging efforts. 

While boat inspections deal with the immediate threat from out-of-state boaters, Matson emphasized that education and outreach remain among the most important components to invasive mussel prevention. In 2016, he said, many boaters were annoyed or reluctant to have their boats inspected because they didn’t fully understand what was at stake. Today, after years of communicating the “Clean, Drain, and Dry” campaign, Matson believes that most people have not only heard about AIS, but also understand the importance of protecting our waters. 

“Taking the local elementary classes on mussel walks and giving them knowledge of ways they can protect the environment empowers them,” he said. “When I mention they are our future leaders I see their chests puff up with pride. It’s that connection between responsibility and respect for our waters that we can truly make a difference for future generations.”