Commercial netting OK'd to target lake trout
An experimental netting project aimed at curbing the proliferation of lake trout in Swan Lake and upstream waters has been approved by Montana Fish, Wildlife and Parks.
Regional Supervisor Jim Satterfield signed off on the project on Aug. 3, and commercial netting is expected to start on Swan Lake by the end of this month and continue for three weeks. That work will be carried out by a Wisconsin-based contractor, Harbor Fisheries.
In October and November, more gill netting will be carried out in known spawning areas by state and federal fisheries personnel.
"All lake trout netted during the project will be killed," states an environmental assessment that outlines the project. "Those that are salvageable and of suitable size for consumption will be field-dressed and donated to food banks or other facilities."
The project is an extension of netting carried out on the lake in 2007 and 2008. That work, however, was aimed at sizing up the lake trout population and identifying spawning areas through random netting.
"Last year was a random sampling approach whereas this year we'll be focusing on areas where we have the highest catch rates," said Leo Rosenthal, a state fisheries biologist. "We're trying to focus on areas where we have the maximum catch rates and a minimum by-catch of other fish, including bull trout."
The project is being pursued out of concern for future impacts of a growing population of non-native lake trout on bull trout, which are protected under the Endangered Species Act. Lake trout were first detected in Swan Lake in 1998. They have since migrated upstream into the Swan River drainage. This year, lake trout were detected in Lindbergh Lake, and there is concern they will eventually show up in nearby Holland Lake.
During a recent 30-day public comment period, the state received 21 written comments, with 14 in support and seven opposing the Swan Lake project. Seven people spoke in favor of it at a public meeting.
Rosenthal said those opposed to the project raised concerns about the project's cost, its impacts on bull trout, and whether it would be a successful effort.
The environmental assessment acknowledges that similar efforts have been carried out with "unproven success' in other waters, such as Yellowstone Lake and Idaho's Lake Pend Oreille.
"However, several of these water bodies are considerably larger than Swan Lake, potentially more complex in terms of habitat and number of spawning locations, and have well established lake trout populations," the assessment continues.
"The relatively small size, relatively shallow depth, and simple shape … of Swan Lake, as well as the newness of the lake trout population, increase the chances of success in a project of this type."
During last year's random netting, 3,874 lake trout were netted and killed, and there was a by-catch of 240 bull trout, about half of which died.
Rosenthal said he expects this year's lake trout catch "to be the same if not higher just based on the increased effort" and more targeted netting on known spawning areas.
Rosenthal said the project will be a "learning experience" and there are no guarantees that it will effectively suppress lake trout.
"We don't know the answer to that and that's why we're doing the project," he said.
The project will cost $50,000 to $60,000 annually, Rosenthal said, and funding has been secured from multiple sources for the next two years.
Those sources include Montana Fish, Wildlife and Parks, the U.S. Fish and Wildlife Service, the U.S. Forest Service, the Montana Department of Natural Resources and Conservation, the Confederated Salish-Kootenai Tribes and Montana Trout Unlimited.
The project is approved to carry on for a total of three years, but funding for the third year "will likely depend on the success of the first two years," the environmental assessment states.
Satterfield is requiring a review to be held each June to evaluate the previous year's work.
Reporter Jim Mann may be reached at 758-4407 or by e-mail at jmann@dailyinterlake.com