Hundreds of trout anglers will head to Montana’s Flathead Lake this fall to compete in a fishing derby where the goal is not to catch the biggest trout, but to reel in the most. The daily bag limit for this contest may be surprising. Organizers encourage anglers to catch as many as 100 lake trout per day.
The Mack Days fishing contest starts Sept. 8 and runs through Nov. 15 and is sponsored by the Confederated Salish and Kootenai Tribes. The Tribes’ goal is to remove as many non-native lake trout as possible from Flathead Lake.
To lure anglers to the months-long fishing derbies that occur in the spring and fall, organizers award as much as $300,000 dollars in prizes annually.
Some of that cash comes from the Bonneville Power Administration’s Fish and Wildlife Program.
Decades ago, non-native lake trout, sometimes called mackinaw, were stocked in Flathead Lake. Since then, the lake trout have caused steep declines of native bull trout and westslope cutthroat trout populations.
The lake trout spawn in the lake, grow very large and eat native trout and their young.
Bull trout are federally listed as threatened, and westslope cutthroat trout is a sensitive species. Biologists say managers need the Mack Days program to curb more losses of the native fish and begin recovery.
“Lake trout are native to the Midwest, and because of their popularity for trophy fishing they were introduced in lakes around the west, including Flathead Lake,” says Barry Hansen, fisheries biologist with the Confederated Salish and Kootenai Tribes. “In almost all cases the introduced lake trout have had negative impacts on native trout. We estimate the lake trout have cut Flathead’s native fish population by two thirds.”
Hungry Horse Dam sits on the South Fork Flathead River and blocks access to an estimated 40% of the bull trout and westslope cutthroat trout spawning habitat. Because of BPA’s responsibilities to mitigate the impacts of federal dams, the agency supports the Mack Days contest to increase native trout numbers in the lake.
“Native trout are important to the lake and the Flathead River’s ecosystem,” says Cecilia Brown, BPA fish biologist. “Bull trout and westslope cutthroat trout migrate from the lake to the upper reaches of the Flathead River Basin to spawn, so they are valuable throughout the watershed. With Hungry Horse Dam blocking one arm of the native fishes’ spawning habitat, its great BPA can support the removal of this invasive species.”
“We know it is not feasible to fully eradicate lake trout from Flathead Lake, so after extensive analysis we set a goal to reduce abundance of adults by 75%,” says Hansen. “Last year through Mack Days and gillnetting we removed 115,000 lake trout. Our goal is increase that number to more than 140,000 to achieve that target level of reduction.”
At 28 miles long and 120,000 acres, Flathead Lake is the largest freshwater lake west of the Mississippi. According to Hansen, historically, the area around the lake lacked the herds of bison or salmon populations other western tribes depended upon. Instead, Native Americans in the area relied on the lake’s large bull and cutthroat trout populations for food.
“Culturally, the Tribes have always depended on the lake’s native fish populations. For thousands of years the fish were key to their survival, especially during long, cold winters when they would fish for bull trout as large as 25 pounds,” says Hansen. “It would be a catastrophe to lose these species now.”
— CBB, Oct. 20, 2017, TRIBES’ MOVING FORWARD ON LONG-TERM PLAN TO REDUCE LAKE TROUT IN FLATHEAD LAKE https://www.cbbulletin.com/tribes-moving-forward-on-long-term-plan-to-reduce-lake-trout-in-flathead-lake/
— CBB, Dec. 21, 2018, UPPER COLUMBIA BASIN BULL TROUT STUDY FINDS SMALL POPULATIONS DECLINING, AT RISK https://www.cbbulletin.com/upper-columbia-basin-bull-trout-study-finds-small-populations-declining-at-risk/
— CBB, Jan. 10, 2014, TO AID LISTED BULL TROUT, LIMITS REMOVED ON TROPHY SIZE LAKE TROUT IN SOUTH FLATHEAD LAKE https://www.cbbulletin.com/to-aid-listed-bull-trout-limits-removed-on-trophy-size-lake-trout-in-south-flathead-lake/
— CBB, July 19, 2013, TRIBES: MORE NEEDS TO BE DONE TO INCREASE BULL TROUT IN FLATHEAD LAKE, INCLUDING LAKE TROUT NETTING https://www.cbbulletin.com/tribes-more-needs-to-be-done-to-increase-bull-trout-in-flathead-lake-including-lake-trout-netting/
— CBB, Sept. 26, 2010, MIGRATING FLATHEAD BASIN LAKE TROUT THREATENING BULL TROUT POPULATIONS https://www.cbbulletin.com/migrating-flathead-basin-lake-trout-threatening-bull-trout-populations/