As a cool morning fog lifted from Swan Lake, the crew aboard the open-deck fishing vessel "Trygg" ventured out to reel in 9,000 feet of gill nets strewn in a serpentine pattern on the southern end of the lake before sunrise.
A hydraulic lift steadily reeled in the nets, bringing up lake trout here and there, along with a few kokanee salmon. Unlike during many other mornings since netting started in late August as part of an ongoing lake trout suppression project, it's a relatively low catch, yielding a few dozen lake trout.
The crew is led by men with the Hickey Bros. contract fishing business out of Bailey's Harbor, Wisc., but also on board are personnel from Montana Fish, Wildlife and Parks, the U.S. Fish and Wildlife Service and the Forest Service.
"It's kind of slow today, but you don't know what's going to happen," said Leo Rosenthal, a fisheries biologist with Montana Fish, Wildlife and Parks. "That's why you have a lot of people out here, because you never know."
Skipper Tyler Long has been with Hickey Bros. for five years and has done lake trout suppression work on Lake Pend O'Reille and Yellowstone Lake. All lakes are different, he says, but there are similarities in fishing methods.
"You just gotta find where the fish are in each lake. It's just like any other kind of fishing," he said. "It comes with its ups and downs."
But so far this fall, the crew's netting success has already surpassed results from last year, which was the first in a three-year project aimed at reducing the lake trout population for the benefit of kokanee salmon and protected native bull trout. It is also aimed at slowing the proliferation of lake trout to other waters in the Swan River Basin such as Lindbergh Lake, where they were first detected last year.
Last fall's netting efforts on Swan Lake removed 5,200 lake trout. Just over two weeks into netting that will end this Friday, 8,000 have already been removed. So far, netting has been concentrated on catching smaller lake trout from two deep basins at the south and north ends of the lake.
Over a three-week period in October, the crew will concentrate on catching adult lake trout that tend to gather for spawning over large, angular rocks that have fallen from the banks on a mile-long stretch along Montana 82.
"We're getting a lot more confident" about where to find spawning activity, Rosenthal said, largely because adult lake trout have been fitted with transmitters and tracked to the deeper waters along the highway.
Last year, 239 adult lake trout were removed during the spawning period, and Rosenthal expects to see a few less caught this year because the lake's adult population is limited compared to younger age classes.
Lake trout were first detected in Swan Lake in 1998, and it is believed they got into the lake sometime in the early 1990s. Because the population is new and limited in size, Rosenthal said, there is an expectation that netting will be successful in suppressing the population to a point where other species will benefit.
The Confederated Salish and Kootenai Tribes have proposed a controversial netting effort on Flathead Lake, with critics asserting that it would turn into a perpetual, costly effort with limited success because lake trout have long been the dominant and popular sport fish on the lake.
Rosenthal says Flathead Lake and Swan Lake are "apples and oranges" when it comes to lake trout suppression, mainly because the Swan Lake population is not well established and Swan Lake itself is a smaller and simpler system.
With smaller fish thriving on mysis shrimp, Flathead Lake's lake trout population boomed to the point where a hugely popular kokanee salmon fishery fell prey to larger lake trout, vanishing in the mid-1990s.
Rosenthal said Swan Lake's kokanee population is doing well, and there is a desire to see that continue.