Jun 11, 2012 6:34 PM by Dennis Bragg - KPAX News
POLSON- Tribal fisheries managers say the semi-annual Mack Days tournament remains a valuable tool for managing non-native trout on Flathead Lake.
Although hundreds of thousands of fish have been caught over the past decade, there's no sign the derby will disappear. Mack Days seems like a fun fish frenzy, but hard science is behind the event.
More than 100 years ago, well-meaning people stocked Flathead Lake with non-native trout. The populations exploded in the 1980s, along with non-native opossum shrimp.
The Confederated Salish and Kootenai Tribes decided to sponsor the "Mack Days" tournament in 2012 to control numbers of the larger, predatory fish that eat the native species like bull trout and westslope cutthroat.
This year, area anglers netted about 38,000 fish competing in the spring derby for $150,000 in cash and prizes. And even when the water is rough, dozens of anglers hit the broad surface of Flathead hoping to catch some of the trout lurking beneath the surface.
"They're very into the process and they seem to have a lot of fun doing it," said Barry Hansen, a CSKT fisheries biologist. "There's a lot of camaraderie between anglers, a lot of information passed on, techniques, and many anglers have improved through the contest."
On one of the last days of fishing, CSKT tribal biologist Evan Smith and fisheries technician Rick Folsom hit an area west of Blue Bay peppered with boats. Top anglers will sometimes fish until the light fades. The fisheries crew collects a few dozen donated fish, marking them for research with clipped fins and tiny "tags" that can be scanned, which is a slippery job on a moving boat.
Each tagged trout is "named" by an assigned number and then returned to the lake, contributing more data about the lake's fishery.
While Mack Days somewhat controls the invasive species, the competition was never designed to completely eliminate non-native trout. Hansen said they've never proposed to completely eliminate lake trout, because Flathead is too big, and it's still important to have them in the fishery, just with controlled numbers.
Hansen added the derby is likely to continue for years to come, since it fits with biologists' developing long-term plans to control lake trout. The fall event will mark the 10th anniversary of Mack Days.