Gill-netting culls 73,000 lake trout from Yellowstone Lake

Gill-netting culls 73K lake trout from Yellowstone Lake. By Mike Stark.Billings Gazette. The more nets they throw into Yellowstone Lake, the more pesky lake trout they seem to catch.

Despite the increase haul of this introduced cutthroat trout-eating predator, the Yellowstone cutthroat are just barely holding their own, if that.






  1. elkhunter Avatar

    Are the animal activist groups freaking out about this? YNP will have their hands full getting rid of them. People need to think before they do stupid things like releasing non-native fish.

  2. Ralph Maughan Avatar

    Nobody knows who or how the lake trout got in Yellowstone Lake, and I don’t know of anyone who opposes getting rid of the lake trout if it is at all possible.

    My pet theory is that it was an accident that came from the 1988 fires — helicopters dipped from nearby Lewis Lake, got some lake trout in the big drop bucket by accident and dropped it on a fire burning a tributary to Yellowstone Lake.

    Most people believe, I think, that it was a deliberate plant by someone who wanted to fish for lake trout.

  3. Dan Stebbins Avatar

    I’m glad we actually have a fish post on here! I actually spent my first summer in YNP in ’01 working on the fisheries boats as a volunteer gill-netting lake trout. 73,000 is an immense number for them. The summer I worked we caught a then-record 24,000.
    Anyway elkhunter I don’t know of anyone that opposes getting rid of the lakers. Frankly if the cutthroat population continues to fall (which it has been), it will effect 42 different species of animals in the GYE. Think about how many animals depend on fishing for the shallow water and stream spawning cutthroat. Bear, Eagles, Osprey, Coyote, Otter, Pelican, etc. In my opinion this is by far the number one environmental issue facing YNP. And most of the biologists do agree that they have their hands full getting rid of them.
    The main reason why lake trout are such a problem is that they hang out at about 60 meters of water and they only come to the shallows (5-20 feet) to spawn, but they still stay in the Lake. This means none of the predators that feed on cutthroats can reach them except in very special situations. Meanwhile, the lake trout can keep feeding on cutthroat and reproducing. It’s a bad, bad deal.
    The fisheries biologists do believe they were illegally planted, although there are those that like your theory Ralph. Frankly, since lake trout are deep water fish I couldn’t see them getting caught in a drop bucket much less surviving the drop itself. I guess stranger things have happened.

  4. Ralph Maughan Avatar

    I have a question about lake trout, Dan.

    Where do the small lake trout hang out before they are large enough to attack other fish? Are they deep too?

  5. Jay Avatar

    There was a good article in the Yellowstone Science magazine several months (maybe longer) ago that discussed the source of the lake trout. It’s been a while since I’ve read it, but if my memory serves me, it sounds as if they’ve got pretty good evidence that the trout were caught in a nearby lake with a known lake trout population and dumped into Yellowstone lake.

  6. Dan Stebbins Avatar

    Hey Ralph,
    You know the shallowest we set nets that summer was about 40 meters (<-if I remember right). The average laker we caught there was about 280 to 350 mm long. I know that the smaller lake trout do hang shallower than the big ones. However they don’t get as shallow as the cutthroat do. We actually most often set nets in the range of 60 to 75 meters. After dark however they will come up shallow to feed on cutthroat, but that usually is a middle of the night deal from what I was told.
    During my time with fisheries they were really experimenting with depth and also width of the net threads. They eventually began to focus on certain depths and net thread. So I’m sure some of the 73,000 is definitely trial and error, but it’s an amazing number. If you’re interested Ralph you can volunteer to go out on the lake with one of their boats next summer when you’re in the park. It was an eye-opening experience for me, not to mention spending a day on Yellowstone Lake is a blast, I did 3 months! Anyway, if you’re interested (or anyone else for that matter), let me know and I can get you in touch with Pat Bigelow. She’s in charge of the Lake crews.

  7. Ralph Maughan Avatar


    I think it was in Yellowstone Science. It’s on-line

  8. Mills Avatar

    Its good to hear that they are having some success. Mechanical removal of a non-native fish is always a daunting task that is rarely completely successful. There have been several successful chemical treatments, but these chemicals (rotenone) are not species specific and are capable of killing all the fish in a lake. Of course, pulling off a chemical treatment of a lake the size of Yellowstone Lake is probably not feasible. I would love to see a mechanical removal project be successful.

    On another note, the Idaho Fish and Game with cooperation from the Utah Division of Wildlife Resources still actively stock lake trout into Bear Lake. Bear Lake supports a large population of Bonneville cutthroat trout, a species that has been petitioned for listing on multiple occasions (and 4 other endemic species). So far the cutthroat seem to be persisting. The state agencies have recently (last 10 years) switched to stocking sterile lake trout. Its a good example of how little we really know about these systems and how much effect a relatively small change can have.

  9. Jim Avatar

    What do they do with all the Lake trout they netted?

  10. Pete Avatar

    I took a guide trip years ago floating the Madison and was told by the senior guide who had lived in the area since he was young that at one time years ago there had been a fish hatchery on the lakeshore that in fact raised Lake Trout. He’d actually seen old historic photos of the operation. The source seems very solid and might answer the dubious issue of where they came from.



Dr. Ralph Maughan is professor emeritus of political science at Idaho State University. He was a Western Watersheds Project Board Member off and on for many years, and was also its President for several years. For a long time he produced Ralph Maughan’s Wolf Report. He was a founder of the Greater Yellowstone Coalition. He and Jackie Johnson Maughan wrote three editions of “Hiking Idaho.” He also wrote “Beyond the Tetons” and “Backpacking Wyoming’s Teton and Washakie Wilderness.” He created and is the administrator of The Wildlife News.

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