Lake trout biggest threat to bull trout recovery

The U.S. Fish and Wildlife Service recently released a step-by-step draft strategy on how best to recover bull trout across the Northwest, including rivers and streams in the Flathead and St. Mary River valleys.

The documents come as the result of a lawsuit filed by Friends of the Wild Swan in 2012. While the drafts are a good step, they leave out one key element — standards for habitat, claimed Arlene Montgomery, program director for the group.

“I find this especially problematic,” she said.

Wade Fredenberg, the author of the documents and a Service biologist, said habitat wasn’t included in the plan because it’s not a regulatory document, it’s an advisory document.

The greatest threat to bull trout isn’t habitat, Fredenberg noted, it’s non-native fish species, particularly lake trout. Once lake trout enter waters that bull trout inhabit, they take over the predatory relationship in the ecosystem.

Flathead Lake was once a thriving bull trout fishery and had a great kokanee salmon run as well. But once lake trout were established, bull trout numbers plummeted and the kokanee salmon runs crashed altogether.

It’s estimated that there are 1.6 million lake trout in Flathead Lake alone.

There are ways to diminish the population. The document calls for netting lake trout from Flathead Lake, with target levels of 143,000 age four and above a year to reduce the lake trout population by 75 percent within 50 years.

It also calls for increased angler harvest through other means, like fishing derbies and even commercial harvest in state managed waters.

The plan also calls for reducing northern pike numbers in the Flathead River. The pike eat bull trout and westslope cutthroat trout. Pike are another non-native predator.

But over the years the lake trout and the northern pike fishery have become popular with anglers.

“People like catching kokanee, too,” Fredenberg noted.

Netting has worked in other mountain west lakes. In Lake Pend Oreille in Idaho, a nearly decade-long netting and angling effort removed nearly 180,000 lake trout from its waters and the kokanee salmon population is doing well.

At last count, the population in Lake Pendoreille was 1.5 million salmon.

The entire documents of the study, which are made up of several volumes, can be viewed online at http://www.fws.gov/pacific/ecoservices/BullTroutRUIPs.htm.