Battle to save Yellowstone cutthroat trout working

After years of effort and millions of dollars spent, the battle to save Yellowstone cutthroat trout appears to be succeeding, as lake trout eradication efforts in Yellowstone Lake have a tangible effect on the population.

The battle to save the Yellowstone Lake cutthroat trout has been going on for years and years, and it’s basically been a blunt-force attack: kill as many lake trout as possible, whether it’s by netting or other means. It’s also a slow process, but an important one. Lake trout have no natural predators in Yellowstone Lake and play no positive role in the Yellowstone ecosystem.

Plus, their presence has one negative effect: they prey on cutthroat trout, with a mature lake trout eating approximately 50 cutthroats a year and competing for the same food sources. And cutthroats do play a very positive role in the Yellowstone ecosystem: they head up tributaries to spawn, serving as a valuable food source to birds of prey, otters and bears. With Yellowstone Lake being home to the largest population of Yellowstone cutthroat trout, saving the cutthroats became a major conservation campaign for Yellowstone officials.

We’ve seen lake trout numbers decline in recent years: In 2018, for instance, we reported netting initiatives at Yellowstone Lake were capturing fewer lake trout in 2018, a reserve from steadily rising numbers in recent years. Another sign of the decline: the removed lake trout are larger than those caught in previous years. Declining numbers of smaller lake trout means a decline in reproduction levels.

Now, in 2020, these netting efforts may be scale back to maintenance levels, per Yellowstone officials. From Wyoming Public Media:

Lake trout will likely never be fully eradicated from Yellowstone Lake, but [Yellowstone Lake Special Project Manager Dave] Sweet predicts that the population will be low enough that they will soon be able to reduce their efforts to maintenance netting.

“The news has just been tremendous for the last couple of years and this year, it really is tremendous. Those big adult fish have declined by 90%. They now represent less than 2% of the overall population of lake trout in that system,” said Sweet.

Photo of spawning Yellowstone cutthroat trout by Jay Fleming, courtesy National Park Service.

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