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April 15, 2010 3:35 am

Fish rehab

Written by Tribune Staff

Ridding park of unwanted fish

About half a dozen Yellowstone National Park personnel and a dozen-plus members of the public dropped by a meeting in Cody on Tuesday to hear the National Park Service's spiel about its campaign to rid the park of unwanted fish and increase native fish.

Topping the list is lake trout overrunning Yellowstone Lake and the service's labors, such as using gill nets, to curb their spread since the mid-1990s.

But some say not enough is being done.

“The Park Service's efforts on Yellowstone Lake are not what they should be,” said Trout Unlimited Council President Dave Sweet. “They need to be more aggressive.”

Due to invasive species, disease and climate change, native fish such as cutthroat trout and Arctic grayling have declined in Yellowstone. To change that, the service is initiating work on a native fish conservation plan, park officials said.

Step one is public input.

The service will analyze those comments, then write an environmental assessment that will be released this fall for public comment. A final decision and plan should be completed in winter 2010-11.

“This is really important for us to get comments,” said Dan Reinhart, supervisory resource management specialist.

Lake trout apparently have the edge, and Yellowstone Lake cutthroat are being edged out or eaten by lakers.

Cutthroats once numbered 4 million in Yellowstone Lake.

“Today we don't know what the population is,” Sweet said.

It could be 10 or 5 percent of the former 4 million.

“Some numbers suggest it may be as low as 1 percent,” Sweet said.

Cutthroats are a keystone species, Sweet said, meaning a host of other critters rely on the trout's continued existence.

“There are 42 species that depend on that Yellowstone cutthroat,” Sweet said, including grizzly bears, otters, ducks, osprey and pelicans.

Cuttroats can't catch lake trout, which lurk in deep water, Sweet said.

The service does not have a lake trout density estimate, said Todd Koel, supervisor for the Yellowstone fisheries program.

Koel said in order to get a lake trout estimate, they would have to catch 10,000 lakers and release them. Once caught, the service would rather dispose of them.

“It's hard to put fish back that are predators like that,” Koel said.

Since the late 1990s, 450,000 lake trout have been removed from Yellowstone Lake — 100,000 last year, Koel said.

Lake trout are voracious. Photos on display show huge lake trout, nearly 4 feet in length. The biggest to date was a 26-pound lake trout caught in September 2009, said Pat Bigelow, fishery biologist.

Bigelow spreads her hands about 10 inches apart to indicate the size of most lake trout that are gill-netted.

Gill-netting works just like it sounds: Lakers are snagged by their gills.

Once the trout are captured, they are killed and their air bladders punctured so they sink to the bottom of the lake, Bigelow said.

Nets are deployed, and the lakers are caught within a day to a week after they are netted, Bigelow said.

A gill-netting contractor spends five weeks on a boat in the spring and five weeks in the fall to snag lake trout on Yellowstone Lake, Bigelow said.

“‘The Park Service has to declare war on the lake trout,'” said Sweet, quoting Michael Hansen, professor of fisheries at the University of Wisconsin, Stevens Point.

Hansen said that, at a 2008 symposium in Chico Hot Springs, Mont., the service invited leading fish biologists to attend. Allowing 10 weeks of commercial gill-netting in the park per year is not enough, Sweet said.

“I really believe if we don't act aggressive, we're going to wake up one of these years and that (cutthroat) population will be gone,” Sweet said.

In one area of the lake, the boat must observe a 5 mph speed limit, thus losing two hours per day traveling to and from the net site. Motorized boat restrictions on other areas of the lake prohibit the boat in those areas, he said.

The service is committed to doing what it can to preserve cutthroats, said Mike Ruhl, fish biologist.

The service is looking at increasing gill-netting efforts, said Jeff Arnold, an aquatic ecologist.

The science panel at Chico suggested ramping up lake trout capture, Bigelow said.

The service could add more contractors, or they could increase the number of service employees capturing lake trout. It would be easier, although more expensive, to employ contractors, Bigelow said.

However, the service needs to keep its federal edict ducks in a row when removing lake trout and stocking other native fish in the structure of an EA.

“We want to do it correctly according to NEPA (National Environmental Policy Act),” said Bianca Klein, environmental protection specialist.

The primary focus is lake trout. Next is addressing the park's headwater streams to restore cutthroats and graylings, Reinhart said.

In the creeks, the service wants to remove non-native brook, rainbow and brown trout, Reinhart said.

“Native species conservation needs to be our objective,” Reinhart said.

“Possible actions will not take place in the main stem of Madison or Firehole rivers,” said a service handout.

Get comments to park headquarters by midnight April 30. Grab a scoping brochure or leave online comments at http://parkplanning.nps.gov/yell.