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Migratory “Super” Cutthroat

Editor’s Note:  This is a guest post from long-time guide here at the lodge, Chris Jensen

This winter I got invited to fish Pyramid Lake Nevada.  Pyramid Lake is known for an ancient strain of cutthroat that are descendants of trout that lived in Lake Lahontan.  Thousands of years ago Lake Lahontan covered almost half of Nevada.  The “Lahontan” Cutthroat of today are measured in pounds, not inches, the biggest of our trip coming in at 15 pounds and 20 pounders can be caught.

Worth driving for!
Worth driving for! 13lb Lahontan Cutthroat

On our long drive back home our thoughts turned to what it must have been like to fish Lake Lahontan thousands of years ago.  It’s rumored that these fish could reach lengths of up to 50 inches!  My close friend Drake chimed in “Yeah, makes me wish I could fish the South Fork before Palisades Dam when there were really big cutthroat in there.”  I asked him why he thought they were bigger back then.  Drake grew up just 45 minutes from the lodge in Rigby and had heard stories of big migratory cutthroat that spawned way upstream possibly as far as above Jackson Lake and then wintered closer to American Falls.  The rumor he had heard is these big fish disappeared once Palisades Dam was completed.  I had never heard this and wanted to learn more.

The following week I sent an email to Brett High the regional fisheries biologist for the Idaho Fish and Game here in the Upper Snake Region.  Here’s my email to him and his reply…

Hi Brett,

I heard a rumor that before Palisades Dam was built that there were migratory Cutthroat that spawned high up in the drainage and migrated back down river.  Have you ever heard this?  Maybe lost in time but I heard that these were the biggest fish in the S. Fork.


Good to hear from you. I hope things are going well. You are right about that rumor of big fish in the South Fork. Check out this clip from Virgil Moore’s 1980 annual IDFG report back when he was the biologist here:


You can access the full report on our website. Here is a link: https://collaboration.idfg.idaho.gov/FisheriesTechnicalReports/Res-Moore1980b%20River%20and%20Stream%20Investigations%20South%20Fork%20Boise%20River.pdf

I spoke with Virgil about these large fish that people observed stacking up at the base of the newly formed Palisades Dam in the 50s and he indicated fisheries scientists at the time suspected this strain of cutthroat were long-distance migrators that may have been going as far downstream as American Falls and spawning up in the Salt River in Wyoming.

Brett High

Regional Fisheries Biologist

Upper Snake Region – Idaho Falls

A 21″ cutthroat while a really nice fish is not uncommon in the South Fork these days.  Did these long distance migrators get bigger?  Has the dam allowed cutthroat to get just as big as these migratory fish?  I’m afraid these questions may never be answered.  The takeaway here should be we need to protect what we’ve got and never take it for granted.