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Montana outdoors: Lirpa Sloof lakers found in Glacier Park
Mark Henckel
MONTANA OUTDOORS
A federal fisheries biologist has discovered the probable reason why native bull trout and cutthroat trout are having such a tough time surviving in the waters of Glacier National Park. Blame it on a highly predatory strain of two-headed, two-stomached lake trout.
Populations of this new strain of lake trout were discovered in last summer's field work at Lake McDonald headed by U.S. Fish and Wildlife Service biologist Fred Wadenberg, from the U.S. Fish Hatchery at Creston.
Research on the new strain is ongoing at the Creston hatchery, in Lake McDonald and in spawning areas for the strain discovered in Lirpa Creek and Sloof Creek, two tributary streams that feed into the lake.
Impacts on bull trout and cutthroat trout from the strain, tentatively being called the Lirpa Sloof Lake Trout, are expected to eventually stretch all the way down the Flathead River drainage.
Looking at the new strain, Wadenberg said it answered a lot of questions that have baffled biologists for years. "We finally figured out why those lake trout seem to eat so much," he said. "Apparently, they've adopted a 'two heads are better than one' foraging strategy."
Fisheries managers are just now exploring the oddities of the anatomy of the Lirpa Sloof lakers and are figuring out possible ways to control the strain's spread.
On the two heads, for example, Wadenberg said that the predatory urge of lake trout must have finally taken over in its evolution. "Lake trout eat, eat, eat. It's the most important thing in their lives," he said.
On the two stomachs that the strain has, Wadenberg said that doubling the stomachs doubled the strain's ability to digest food, allowing it to grow more quickly than its single-stomached competitors.
Liabilities in the evolution of the strain, on the other hand, include the fact it doesn't have a tail. The strain is not able to swim real well and chase food items. Hence, it's more of an opportunistic predator that relies on ambushing prey that swim real close to its toothy mouths.
Some of Wadenberg's fellow biologists feel that this inability to be a strong swimmer might be the factor that will eventually limit the upstream spread of the Lirpa Sloof lakers. "They aren't able to leap over even the smallest of waterfalls to go upstream," Wadenberg said. "On the other hand, because they can't swim well or fight currents real well, they are easily swept downstream by high water during snowmelt runoff. That's how they're spreading down the drainage."
Decidedly against the strain is also the fact that with two heads, there are also two brains at work and sometimes the species fights against itself in streams and rivers. "When it gets to a fork in the channel, the heads fight against each other and often, the fish can't decide which way it wants to go," the biologist said. "We've found exhausted Lirpa Sloofs stacked up in these areas, literally starving because they can't decide which of the channels it wants to feed in."
As a result, one defensive strategy being discussed to slow the spread of the species will be to create more side channels. "Between the ongoing research and the construction, it'll be an economic windfall. We're estimating the cost to be $150 billion to side-channelize the entire Flathead drainage. But it will be well worth it to save a few bull trout and cutthroats. We've got to think about those native species first, foremost and always," Wadenberg said.
Yet another defensive strategy – and a far more certain way of eliminating the strain – will be to poison out the fish populations of the entire Flathead drainage and start over. "Sure, we'll kill a few million fish. Sure, it's expensive," he said. "But think of the profits that the chemical companies will make in selling us the poisons. It will be great for economic development in the chemical industry. And when we ask Congress for the money to do this, what politician is going to vote against economic development?"
Wadenberg feels that the only threat to the economic windfall that either the side-channelization or the poisoning could bring to northwestern Montana would be the possibility that some congressional staffer who reads the legislation would turn out to be dyslexic.
