Fishing for a Cause

By: Fiona Handler, Big Sky Watershed Corps Member serving with Flathead CD

The 2021 Mack Days fall fishing tournament officially began yesterday, September 16^th, and will run until November 14^th. This event is hosted by the Confederated Salish and Kootenai Tribes (CSKT) in association with Montana Fish, Wildlife, & Parks and its primary goal is to help manage populations of non-native fish in Flathead Lake.

Lake trout were introduced to Flathead Lake in 1905 and have since become the most dominant fish in the lake. However, the Lake trout success story actually begins with kokanee salmon. Kokanee salmon were introduced to Flathead Lake in 1916 as a sportfish, and as the total population increased, so did the number of local bears and eagles that happily fed on the tasty fish. In the 1970s, fisheries managers began stocking lakes with Mysis shrimp, with the intention of increasing food resources for sportfish like kokanee salmon that brought high traffic of fisherman and tourists.

When lake trout were first introduced to Flathead Lake, their population stayed consistent and in balance with native fish species. However, introduction of Mysis shrimp caused a shift in the foodweb. Mysis shrimp are nocturnal and dwell at the bottom of the lake during the day, and rise to the surface at night to feed on plankton. Mysis shrimp at the bottom of the lake became a food resource for immature lake trout that also live at the bottom of the lake. Once mature, lake trout move into surface zone of the lake and prey on other fish, such as kokanee salmon. Kokanee salmon are visual feeders that spend the daytime hours feeding on plankton near the surface of the lake. With competition for plankton from the Mysis shrimp, and predation from increasing numbers of Lake trout, Kokanee salmon and native fish such as bull trout declined, and lake trout came to dominate the foodweb in Flathead Lake.

The CSKT have begun to implement programs to remove non-native lake trout. Mack Days fishing tournaments began in 2002, and over 660,000 lake trout have since been removed form Flathead Lake by participating anglers. Another program that the CSKT started is a non-profit organization called Native Fish Keepers. Lake trout that Native Fish Keepers catch is sold at numerous grocery stores in Flathead Valley and all the profits help the organization work to complete their goal of removing 75% of the lake trout population so native trout species have a better chance of competing with non-native species.

Find out more about the tournament on the Mack Days website, plus tons of useful information such as how to properly identify native from non-native fishes in Flathead Lake.