In 1994, the first non-native lake trout was caught by an angler in Yellowstone Lake. Since 1995, the Park Service has been gill-netting lake trout in an effort to curb lake trout consumption of cutthroats.
A 2008 panel of scientists said the current level of gill-netting has reduced lake trout predation on cutthroats, but those efforts have not driven lake trout into decline. A substantial increase in suppression of lake trout is needed to win the battle, their report said.
Todd Koel, supervisor for the Yellowstone fisheries program, said the Park Service intends to double its lake trout netting efforts on Yellowstone Lake in accordance with the panel’s recommendation.
If commercial netting efforts are doubled to 20 weeks, it is assumed that would result in a 0.45 predicted lake trout mortality rate, which, in turn would equal an estimated 0.86 population growth rate, according to the environmental assessment.
A commercial netting boat, employed for 10 weeks last year, will be on the lake for 17 weeks this summer. The boat will be equipped with a net and fish trap. Another commercial craft will be used for eight weeks. Two Park Service gill-netting boats will be netting as much as possible, said Pat Bigelow, Yellowstone fishery biologist.
A 44 percent kill ratio is needed to drive the population down, but the service does not know exactly what the population is, said Trout Unlimited Council President Dave Sweet.
The service is guessing and hoping that increasing the number of boats with nets will achieve those results, Sweet added.
The service can project lake trout population growth or decline by random sampling throughout the lake. If the net catch is doubling every year, it is safe to conclude the population is doubling. On the flip side, if they’re catching half of what was landed the year before, it’s safe to assume the population has dropped, Bigelow said.
“Even without a population estimate, you can monitor rates of change,” Bigelow said.
Bob Richard, of Grub Steak Expeditions said, “I didn’t feel good about them solving the problem in Yellowstone.”
Richard said Friday he believed Koel’s intentions were good.
“I think he’s doing the best he can with the staff he’s got,” Richard said.
But that is of limited value when the service does not know how many lake trout there are in Yellowstone Lake, he said.
“They’re netting without a clue of what the results will be,” Richard said.
Richard said Koel needs more staff, money and outside help to find solutions.
“I think they’re trying,” Richard said, “they just need a lot of help.”
The service is aware of two spawning beds and five locations in the lake where there are large concentrations of spawning lake trout, Bigelow said.
“We feel like we have a good general idea where they’re spawning, but we only verified two spots,” Bigelow said.
The service needs to map the beds so it will be prepared when that egg-targeting research is available for implementation, Sweet said. Killing the eggs is crucial to reducing the lake trout population, he said.
Koel said he would like Trout Unlimited’s assistance, and Sweet said the organization would help.
Cutthroats must be re-established in the tributaries feeding the lake, Richard said.
Daniel Wenk, Yellowstone’s new superintendent, must make cutthroat preservation one of his top priorities, Richard said.
Bigelow said $1 million has been slated for the commercial boat, park service vessels and staff this year.
The service has not been doing enough to eliminate lake trout, Bigelow said. But now they hope to at least reduce the population to allow cutthroats to recover and keep the lake trout population at bay until technology can be developed such as attacking lake trout eggs.
Richard offered food for thought, saying cutthroats are surviving in Buffalo Bill Reservoir with lake trout.
To rid the lake of lake trout and keep native fish in Yellowstone’s rivers and streams will require funding.
Failure to preserve cutthroats in Yellowstone Lake is not an alternative, Koel said.
“It’s never been an option,” Koel said.
All written comments on the plan must be received or postmarked by midnight, Jan. 31. The Environmental Assessment and an electronic form to submit comments on the Internet can be found at http://parkplanning.nps.gov/yell. A hard copy or CD of the EA is available by calling 307-344-2874, or by writing to the Native Fish Conservation Plan EA, National Park Service, P.O. Box 168, Yellowstone National Park, Wyo., 82190.