The Confederated Salish-Kootenai Tribes are poised to move forward with a controversial lake trout suppression plan on Flathead Lake, with gill netting tentatively set to begin as early as April.

The tribes published a final environmental impact statement in the Federal Register on Feb. 21 and public input on the document must be submitted by March 21.

The Tribal Council is widely expected to issue a record of decision approving the project soon after that deadline.

Barry Hansen, the lead tribal biologist on the project, said an implementation plan is being drafted, tentatively setting a goal of removing 90,000 to 100,000 lake trout from the lake this year through general angling, the spring and fall Mack Days fishing events and gill netting.

The tentative target for gill netting this year is about 30,000 lake trout, but Hansen said that could be adjusted depending on angler success or other factors.

He stressed that the concept of “adaptive management” will be at the center of implementing the project.

“This is not a blind charge forward,” he said. “It is the same progression we’ve done for the last 14 years with a new tool (gill netting) that we will apply carefully and incrementally. And there will be plenty of opportunity for people to see the results.”

To have the most latitude, the tribes are pursuing the most aggressive of four alternative approaches outlined in the environmental impact study.

That calls for removing up to 143,000 lake trout every year to achieve a 75 percent reduction in lake trout abundance over 50 years. The cost is estimated at around $934,000 per year.

“There’s a lot of latitude in how we proceed, both in scale and timelines,” Hansen said, stressing that the environmental impact study does not bind the tribes to remove as many as 143,000 lake trout per year.

Annual harvest targets could vary substantially from year to year, depending on a variety of factors, and the tribes will take input from the public and other agencies in determining annual goals, Hansen said.

The main purpose of the project is to benefit native bull trout by suppressing the numbers of non-native lake trout, which have become a dominant predator in the Flathead Lake and river system. Introduced in the early 1900s, lake trout have gradually displaced a bull trout population that is now estimated to number only 3,000 adult fish.

Montana Fish, Wildlife and Parks initially was involved with development of a draft environmental impact study for the project, but the agency withdrew as a co-signer, citing concerns about the content and process involved in developing the study.

Both the tribes and the state were involved with a co-management plan for Flathead Lake that expired in 2010, and the two entities have a major disagreement over one aspect of that plan — maintaining bull trout at “secure” population levels. Those levels are partly defined by a minimum threshold of redds, or bull trout spawning beds, that have long been surveyed in upstream tributaries.

The state maintains that bull trout are now 50 percent above “secure” levels and the co-management plan did not call for moving toward aggressive lake trout suppression measures such as gill netting unless bull trout dropped below secure levels.

The tribes, however, have a different view.

Hansen said the overriding goal of the plan was to pursue measures to increase native trout populations, and the efforts that have been undertaken since the plan was adopted in 2000 have not been successful in attaining that goal.

Keeping bull trout above “secure” population was not a goal, he said. “Increasing native trout, that is the real and meaningful goal to us, not ‘secure.’ That is an aside.”

The final environmental impact study, with more than 400 pages, can be downloaded at the Mack Days website, where comments may also be submitted.

The site can be found at http://www.mackdays.com/DEIS.

Reporter Jim Mann may be reached at 758-4407 or by email at jmann@dailyinterlake.com.