Waters: Yellowstone Lake — a cut above

Yellowstone-Cutthroat-Trout-Spawn-2-©-Jay-Fleming-350x232A single fish.

That’s all it took to send a shudder through every fisheries biologist from Mammoth to Fishing Bridge on that fateful day on Yellowstone Lake in 1994.

A single fish.

It was a simple lake trout, or mackinaw, but it’s appearance on the end of an angler’s line was ominous at best. For it was certain that where there was one, there were many, many more — horrible news for a struggling native, the Yellowstone cutthroat trout, which relied on Yellowstone Lake as the safety-deposit box for its future.

I thought about that day not long ago as I stood on a trawler in Yellowstone Lake on a sun-kissed August afternoon, gazing over the side into a net prison where at least two dozen football-sized lake trout swam in the cool waters.

These fish were about to be surgically implanted with expensive transmitters. Nearby, two nimble-fingered biologists were making small incisions on underbellies, inserting transmitters and sewing them back up as casually as if they were tying their shoes.

Lake-trout-incision-350x308Once rejuvenated in their boat-side pens, the fish would be set free to swim past strategically placed receivers toward deep spawning grounds. Once discovered, these sites could be destroyed with a huge underwater vacuum or some other means.

Judas fish, they were called.

Behind the boat, giant gill-nets stretched into the choppy blue waters, extending for one-third of a football field. Several hundred yards away, another boat, operated by expert Great Lakes gill-netters from Wisconsin, dragged the depths for fish that were immediately dispatched.

At one point, a motorboat pulled up alongside, asking for a free lunch. The cutthroat fishing hadn’t been so hot. The gill-netters handed over dozens of the lake trout.

By the end of that summer, nearly 300,000 lake trout would be removed. This summer, with an extra boat on the water, the crew is a mere 10,000 ahead of last year’s take, at about 191,000.

Emphasis on “mere”.

The relatively slight increase is a sign that efforts to suppress the lake trout population is working. We’ll know for sure in late August, when cutthroat trout are counted.

It’s a great story — and not just a tale about restoring a species on which no fewer than 42 Yellowstone critters depend for sustenance during the cutthroat’s annual spring spawning runs (lake trout swim too deep to be of use to grizzly bears, otters, eagles, osprey and the like).

It’s also a great people story.

Old-timers remember the days when anglers lined Fishing Bridge shoulder to shoulder to catch the mighty cutthroat as it migrated up and down the Yellowstone River. Former workers at Fishing Bridge and Lake fondly recall getting off work, taking the few strides down to the lake, catching cutthroat on nearly every cast, and returning for a fine feast.

Those days are long gone.

The illegal introduction of lake trout into Yellowstone Lake sometime in the mid-1980s — how and why is still the subject of great debate — had an immediate and devastating effect on cutthroats. About 90 percent of the population has disappeared into the jaws of the voracious lake trout, which consumes up to 41 young cuts a year.

On Clear Creek, a tributary of Yellowstone Lake, more than 18,000 cutthroats passed through a weir in 1998. A decade later, that number was down to fewer than 200.

It’s now a rare treat to see a migrating cutthroat leaping into the froth at LeHardy Rapid on the Yellowstone River, a la Alaskan salmon.

In a time of a warming climate, with cutthroat trout habitat shrinking, losing Yellowstone Lake as that safety-deposit box could signal the need for Endangered Species Act protections.

The National Park Service has made recovery of the Yellowstone cutthroat a major priority, and the Greater Yellowstone Coalition has been supporting the effort financially and otherwise. I brought reporter Kirk Johnson of the New York Times along on our boat to showcase an extraordinary endeavor.

Happily, for the first time last year the number of Yellowstone cutthroat trout in Yellowstone Lake increased. We are anticipating an even more hopeful outcome this year.

It’s unlikely we’ll ever completely remove lake trout from Yellowstone Lake, and it’ll be a long-term effort.

But we can at least reduce numbers enough so that the catching of a single fish no longer sends shudders through fisheries biologists and anglers.

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