Our native bull trout and westslope cutthroat trout were doing just fine until the lake trout population exploded in Flathead Lake due to the misguided introduction of Mysis shrimp. Large runs of adfluvial cutts and bulls would head up river every spring to spawn. Several years later the young return to the lake to grow and mature before beginning their own journey upstream. And the fishing was great!
When I go fishing, I certainly don’t seek out controversy or conflict. It’s never a lot of fun when you pit one trout or one type of trout fisher against another, but it has become inevitable in the case of lake trout in Flathead Lake. That’s because there is irrefutable evidence that lake trout are the primary reason for the precipitous decline of bull trout and westslope cutthroat trout in the Flathead Lake and River system.
Consider the status of these three fish. The range of bull trout in the Columbia River system has been reduced by more than 50 percent. Native bull trout, once plentiful in the Flathead system, are now listed as a threatened species under the Endangered Species Act (ESA). As Flathead lake trout populations continued to expand in the 1990s and 2000s, the bull trout population declined by over 50 percent. Lake trout expansion has all but wiped out this iconic native in 10 of 13 lakes in Glacier National Park. The Middle Fork, North Fork and mainstem of the Flathead River are closed to fishing for bull trout.
The situation for westslope cutthroat trout is not quite as perilous, but they occupy only 59 percent of their historical range. If populations continue to be depressed, they may be listed as threatened under the ESA. The large runs of adfluvial cutthroat trout from Flathead Lake decreased by up to 60 percent as the lake trout population expanded.
Conversely, the range of non-native lake trout is increasing. Predatory lake trout decimated the Yellowstone cutthroat population in Yellowstone Lake by over 90 percent with cascading effects across the ecosystem. A multi-year netting program to reduce lake trout numbers is showing positive results. Idaho Fish and Game is undertaking aggressive action to reduce lake trout in Lake Pend Oreille and initial results are encouraging (ironically the lake trout moved down the river to Idaho from Flathead Lake). Montana Department of Fish Wildlife and Parks and U.S. Forest Service, supported by the Flathead Chapter of Trout Unlimited, are currently engaged in lake trout suppression on Swan Lake.
Ideally angling alone would be sufficient to reduce the lake trout population. However, even with Mack Days, the population is not declining in sufficient numbers to benefit native species. Like most anglers, I enjoy catching a big fish, but I struggle with the slot limit imposed by Montana Fish, Wildlife and Parks to favor development of trophy lake trout given their impact to our native trout.
I applaud the Confederated Salish and Kootenai Tribes for their initiative in exploring options to reduce lake trout numbers in Flathead Lake. It is a daunting task given the size of the lake, the number of fish and the expected opposition from a constituency of anglers who enjoy fishing for lake trout. Keep in mind that there will still be plenty of lake trout and fishing opportunities even with the most aggressive suppression alternatives. Furthermore, the suppression effort will employ adaptive management. The impacts are not irreversible and methods will be adapted over time as more experience is gained and new technologies improve.
When a species is listed as threatened, I believe we have an obligation to attempt to restore that species so that it is no longer listed under the ESA. We have done that successfully with the bald eagle, whooping crane and black-footed ferret and we can do it with bull trout. Maintaining the status quo is a perilous course that could eventually lead to the listing bull trout as an endangered species.
So what is the right thing to do? From my perspective, the right thing to do is to protect and restore our Montana natives.
Flathead Valley Chapter, Trout Unlimited
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