Mussel signs found in Flathead Lake

The results are not conclusive, but

Fish, Wildlife and Parks officials reported last week signs of

exotic mussels were found in a routine plankton sample taken in

July from the northern end of Flathead Lake near Woods Bay.

The larval samples were collected

during routine water-quality sampling conducted by the Northwest

Montana Lakes Volunteer Monitoring Network, a partnership between

FWP, the Flathead Basin Commission and the Whitefish Lake

Institute.

Eileen Ryce, FWP’s aquatic invasive

species coordinator, said microscopic larvae suspected to be from

exotic mussels may be contained in four of 17 plankton samples

collected from the 200-square-mile lake between May and August. The

samples were sent to three out-of-state laboratories for

testing.

“These larvae are notoriously difficult

to identify at this stage of development,” she said. “With this

sample, the question mark is the size of the larvae, which are

significantly smaller than what we’d expect. But we’ll err on the

side of caution.”

Ryce said FWP will send a team of

divers to several locations on the north end of Flathead Lake to

search for adult mussels, which can be as tiny as sesame seeds.

First discovered in the U.S. in the

Great Lakes in the 1980s, zebra mussels have since spread

throughout the Midwestern and mid-Atlantic states. They were likely

transported in boat livewells, where the microscopic larvae can

survive for weeks. Western states sounded the alarm in 2007 when

quagga mussels were found in Nevada’s Lake Mead.

A predator doesn’t exist in the U.S. to

keep exotic mussels numbers in check. They can reproduce and spread

rapidly, especially on hard surfaces like docks, piers and boat

hulls — even the shells of living organisms, such as lobsters and

clams. The mussels can also block water intake pipes, clog

irrigation systems, disrupt water purification and hydropower plant

operations, and may impact fishery populations.

The Flathead Lake sample that contained

the suspicious, microscopic larvae was among 11 collected from the

lake by volunteers from the Whitefish Lake Institute in July and

delivered to FWP in late September. The remaining suspected samples

will be submitted for additional DNA testing.

“We started collecting zebra mussel

presence/absence samples in 2009 as part of the Whitefish to Eureka

Volunteer Lake Monitoring Program due to the increased zebra mussel

threat in Northwest Montana,” Whitefish Lake Institute executive

director Mike Koopal said.

The lake-monitoring program was started

in 2008 to engage “citizen scientists” and to develop trend

information on local lakes. The program combined with the Flathead

Basin Commission Volunteer Monitoring Program in 2010 and now

monitors about 60 lakes.

Koopal said the good news is that

samples from Whitefish Lake and other local lakes for the past two

years have come back negative for signs of zebra mussels.

“However, I do have significant

concerns regarding the possibility of zebra mussels invading

Whitefish Lake and other local lakes,” he said. “This past year, we

sent our intern to City Beach to conduct boat surveys to determine

where boats are coming from and if people had heard of the

different invasive species, in order to assess the threat here in

Whitefish.”

Koopal said he knows of one confirmed

case of a boat that traveled here from Lake Mead.

“The information I got is that the boat

looked very clean and had gone through inspection stations in other

states,” he said. “But that doesn’t mean zebra mussels or their

larvae could have been missed in the inspections. Larvae can live

in the residual water in a boat motor for extended periods of

time.”

Koopal said his group has also started

sampling for calcium to determine what local lakes would promote

the growth of zebra mussel shells.

“The bad news is that most lakes have

an adequate calcium source to promote growth,” he said, “but there

are myriad factors on whether a water body will be conducive to the

infestation of an invasive species.”

FWP contacted downstream partners in

Idaho, Washington and Oregon on Nov. 12 to alert them of the

suspicious finding. The states agreed the evidence was not

sufficient to trigger a rapid response program, which would

immediately include evaluating control, containment and eradication

options. Ryce noted that the states will remain in close

communication as follow-up testing continues.

Koopal called the finding a wake-up

call for residents in Whitefish.

“I know it’s hard for people to

envision the consequences of a zebra mussel infestation, but it

will be crystal clear if it happens,” he said. “I’d hate to see our

water quality change, or the ecology of the lake shift, or for us

to lose recreational opportunities.”

During Montana’s last legislative

session, Senate Bill 343 was passed earmarking $300,000 for the

prevention of aquatic invasive species statewide.

“That’s literally a drop in the bucket

compared to the funding appropriated by other states already

affected by aquatic invasive species,” Koopal said. “Montana needs

to take a stronger stance on this complex issue by strengthening SB

343 and forming more state-to-local partnerships.”

Moving forward, FWP, the Flathead Basin

Commission and the Whitefish Lake Institute have partnered to fund

a full-time position to administer the volunteer monitoring

program. The position is currently advertised online at

www.whitefishlake.org.

“Montana’s best defense against

invasive species is for boaters and anglers to inspect, clean and

dry their boats, trailers and fishing gear after each use,” Ryce

said.

Citizens can report anything suspicious

they find in local lakes by visiting online at www.nwmtlvnm.org.

For more information on zebra mussels, visit online at fwp.mt.gov

and click “Inspect. Clean. Dry.”