conservation overkill?

To Protect Cutthroat, the South Fork of the Flathead to be Poisoned

By Dave Loos, 9-14-07

	The westslope cutthroat trout. Courtesy of Joseph Tomelleri. Montana Fish, Wildlife & Parks.

It sounds like the most drastic of measures—killing an entire natural fishery in order to replace it with another. 

But federal and state officials, and some environment groups, say a controversial plan to poison 21 lakes and streams in the South Fork Flathead River Watershed in Northwest Montana beginning next month is a necessary move, aimed at protecting one of Montana’s prized species, the native westslope cutthroat trout.

Others, including many local ranchers, businesses and outfitters, maintain that the Westslope Cutthroat Conservation Project’s attempt to remove rainbow and hybrid trout species from the drainage is destined to fail, causing further damage to fragile ecosystems.

The opportunity for opponents to comment, however, has long passed, and barring unforeseen circumstances, Montana Fish, Wildlife and Parks officials will begin treating two lakes in the Jewel Basin with potent piscicides in early October. The ultimate goal: Remove nonnative trout and their offspring so they can’t hybridize with the westslope cutthroat, and then re-establish a new fishery using the genetically pure species.

Sometime in early October, wildlife officials are expected to begin treating lakes in the Jewel Basin with rotenone and other fish toxicants to remove nonnative rainbow and hybrid species. Black Lake and Blackfoot Lake are up first, to be followed over the next decade by 19 other lakes in the South Fork Flathead Drainage.

All 21 of the targeted lakes are on public lands: Eleven are located in the Bob Marshall Wilderness Area, eight sit in the Jewel Basin Area, and two others are located elsewhere in the Flathead National Forest. In addition to nonnative rainbows and cutthroats, the South Fork of the Flathead River itself, according to MFWP, is home to many other fish species, including the abundant mountain whitefish and the bull trout, the latter listed as “threatened” under the Endangered Species Act.

First proposed in 2002, the joint federal and state Westslope Cutthroat Conservation Project is what officials call a necessary program to protect the threatened genetic line of the native cutthroat. In each of the 21 lakes, officials will move to quickly establish a new fishery of genetically pure fish as soon as all non-native hybrids have been eliminated.

While the Bonneville Power Administration is lead agency on the project and will fund the program, they have contracted out operations to MFWP. Wildlife mangers there will do almost all on-the-ground work over the next 10 years, undertaking a project that has faced scrutiny and controversy from the beginning.

MFWP officials say it will take about three days to treat each lake with rotenone, an organic piscicide derived from a tropical plant that disrupts cell function and blocks respiration in fish.

“It will get anything aquatic that’s breathing,” said Mark Shaw, a conservation manager with BPA. Shaw said the rotenone has been used for more than 70 years on similar projects and poses no threat to humans or plant life.

Both Black and Blackfoot Lakes will then be restocked with westslope cutthroat early next spring. 

While commonly used to kill large populations of fish, administering rotenone to lakes and streams in the South Fork poses several challenges for project managers, including getting the dosage right and making sure the toxicant mixes with all the water. Shaw said the poisoning is conducted in the fall so that water levels are low and temperatures are more consistent at all levels of the lake, allowing the rotenone to mix effectively.

“Anything we can do to protect this species is worth doing,” said Mark Aagnes, conservation director for Trout Unlimited. “This area is the final stronghold of the westslope cutthroat trout, and we need to preserve the genetic purity.” He said the Hungry Horse Reservoir would block the invasion of other species in many of the lakes once the cutthroat populations had been re-established.

But such assurances did little to quell the anger of many locals during public comment on the proposal, some of whom accused BPA of undertaking an unnecessary project in order to keep the cutthroat off the Endangered Species List, a listing that could make the agency at least partially liable for protection measures. Now, the cutthroat is a “Montana Fish of Special Concern.”

“These thriving, healthy, big fat fish should not be killed purely for genetic reasons,” wrote Virgil and Barbara Burns, owners of the Bob Marshall Wilderness Ranch, in a 2003 letter to officials conducting the project’s Environmental Impact Statement. “These fish pose no threat whatsoever to pure westslope cutthroat.”

Ernie Barker, president of the Professional Wilderness Outfitters Association, accused the agency of taking drastic action despite no imminent threat to the cutthroat, adding that “the size and scope of this project and the lake sizes is untested in relation to getting a good kill on the existing fish populations.”

Brian Marotz, an MFWP fisheries biologist and one of the lead officials on the ground, attempted to explain the controversial program three years ago in an agency publication as public comment time came to an end. He said the pure-strain cutthroat weren’t completely protected from nonnatives or hybrids by the Hungry Horse Dam. “Some mountain lakes have been ‘leaking’ hybrids into the genetically pure cutthroat population downstream,” he wrote. “We’re losing the pure strain awfully fast, and once they’re gone, they’re gone for good.”

“If they were just picking drainages and starting to kill fish just so we could have a certain fishery, that would be reason for pause,” said Aagnes, who also said the native fish are more adept at dealing with climate changes and handling adversity than rainbow and hybrid species. 

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