CSKT looks to remove lake trout

POLSON — Flathead Lake was, not very long ago, a very diverse fishery, home to kokanee salmon, lake whitefish and lake trout, among many other species. Mysis shrimp were introduced to the lake, with the idea of benefitting the salmon, but that fishery collapsed shortly and the lake trout population quickly boomed. Now, with roughly 1.5 million lake trout inhabiting Flathead Lake and their growth slowing, other fisheries are in jeopardy.

In an effort to reduce the non-native lake trout population and boost the diminished native bull trout and cutthroat trout populations, the Confederated Salish and Kootenai Tribes Division of Fish, Wildlife, Recreation and Conservation is attempting to implement a lake trout suppression project in Flathead Lake.

The main problem, according to manager Tom McDonald, is that lake trout aggressively prey on other fish, most notably the bull and cutthroat trout species, putting them in danger of elimination from Flathead Lake. Estimates have the bull trout population at roughly 3,000 (1:500 ratio with lake trout) in Flathead Lake, a number that has them listed as a threatened species under the Endangered Species Act.

McDonald’s department has been working to avoid further decline and boost numbers of native fish by looking at all the factors that play into the current situation, and are involved in an Environmental Impact Statement (EIS) to come up with alternatives to reduce to lake trout population. As part of the EIS, the CSKT analyzes a range of alternatives to see how removing certain percentages of lake trout (they’re looking at 0, 25, 50 and 90 percent removal) would affect the survival of native trout.

Once the lake trout population goes down, other fisheries will be able to rebound. Bull trout spawn in tributaries, make their way to the lake and eventually return to where they initially spawned. However, juveniles are very vulnerable to predation by lake trout, and that’s why McDonald says that the potential netting project will benefit native fish.

“Once you put pressure on, they’ll respond,” McDonald said. “The reproductive rate will increase and they’ll fight back.”

While it may take years to definitively determine how successful the suppression project would be for bull trout, McDonald is sure that progress will be made.

“Even if we can’t measure for years, we can be confident it’s happening, but ultimately, we’ll need to measure and confirm it’s working before we do this forever,” McDonald said.

The CSKT is planning to send the draft EIS to the Bonneville Power Association’s Independent Scientific Review Panel in the coming days in order to get their perspective on how the netting project would impact the fisheries.

“We want the scientific review panel to look at our information to get the best science possible by the most intelligent scientists that we can find,” McDonald said. “We want those reviews so that our decision-makers can have the best information.”

The EIS is expected to be completed near the end of the calendar year, but has recently lost support from Montana Fish, Wildlife and Parks. In a letter to McDonald, Fisheries Bureau Chief Bruce Rich requested their name be removed from the EIS submitted to the scientific review panel because they believed it was incomplete in content and process. FWP was also concerned that the document would appear pre-decisional to the public. McDonald responded, hoping to clarify the issues, by saying that the intent of seeking scientific review was to “incorporate any useful input to strengthen the scientific information related to making an informed decision” and that the ISRP is not reviewing a final document, rather “the scientific underpinnings of an early draft needed to help craft the various final NEPA (National Environmental Policy Act) alternatives.”

FWP isn’t the only one concerned about the potential project. Some charter fishermen on the lake are worried about how a netting project might impact their business, but McDonald believes that because they primarily seek trophy fish, they shouldn’t be impacted much.

“No matter what we do, there will always be a number of those,” McDonald said.

While resorting to a netting project isn’t a dream scenario, it’s a necessary one given the circumstances, according to McDonald. The success of Mack Days, an event introduced in 2002 that takes place twice a year, has been a key factor in removing lake trout, but despite the huge numbers of fish they tally (34,350 in the spring of 2010, a number that could be eclipsed in 2012), it hasn’t quite made enough of an impact.

“(Mack Days) has grown so much and reached this goal that we set earlier that’s on the edge of starting to suppress lake trout, but it’s not enough to make a meaningful difference, which is why we’ve gone to the EIS,” fisheries biologist Barry Hansen said.

The CSKT has also investigated bounty fishing in an effort to increase harvest by anglers, but despite the support of local representatives, it wasn’t passed by the state legislature at the last session.

Regardless of the outcome of the EIS, however, recreational fishing is one of the most important tools in regulating lake trout populations and McDonald is hoping that people keep hitting the lake, poles in hand.

“We need anglers to continue to put suppression activities on these fish,” McDonald said. “Without anglers, we have to do more heavy-handed type management actions.”