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Search for the Yellowfin Cutthroat

Post By: Wilderfish      Posted: 5/16/2024 8:54:38 AM     Points: 26    
Historical accounts of the Yellowfin Cutthroat from the late 19th century are pretty interesting. A cutthroat trout subspecies that allegedly reached 30 inches and over 10 pounds swimming around in the Twin Lakes makes me want to but a white lab coat and look for used DeLoreans on Craigslist so I can take my fly rods back in time. Hope they find some relic populations out there like they did with the San Juan and Greenbacks so catching this fish is a reality in my lifetime.

[log in for link]
 Reply by: IceAngler86      Posted: May. 16, 9:59:48 AM     Points: 656
Great piece! Thank you for sharing! Would be a fun fish to catch for sure.
 Reply by: k_hine      Posted: May. 16, 11:22:32 AM     Points: 5008
Yeah that's a cool read. I have a few older copies of James Prosek's trout book. I assume some of the images in this article are his sketches.

I really doubt there are any yellowfins here in the valley. However I think searching in eastern France or the black forest of Germany may be smart. I remember reading that the Leadville hatchery traded yellowfins for browns around the turn of the century. Legend has it that those yellowfins were distributed to France and Germany. I'll have to dig through my books at home to cite that, but it's definitely in the common fishing lore around here.
 Reply by: Wilderfish      Posted: May. 16, 1:14:41 PM     Points: 26
That's very interesting that there could be yellowfins swimming somewhere in the Alps right now.
 Reply by: eholm      Posted: May. 17, 11:47:29 AM     Points: 18072
Cool article, thanks! I'm glad the article mentions the late Dr. Robert Behnke who played a role in the discovery and reintroduction of the Lahontan cutthroat, which is one of my favorite trout success stories.

While I understand the desire to find a genetically pure yellowfin cutthroat (and that would be the most exciting outcome), I also think it would be interesting to identify yellowfin genes in a "non genetically pure" cutthroat.

k_hine - that's a wild thought to think of them possibly being in Europe. That would be such an epic discovery.
 Reply by: k_hine      Posted: May. 17, 2:00:21 PM     Points: 5008
eholm is correct. Logically, this is a search for yellowfin genes, not a search for yellowfin fish.

Even if the Europe rumor is true, assuming there were other cut species in the same water, wouldn't yellowfin genes be bred out by now? Anyone know how long the genetic drift or gene flow (i don't know the correct term) is for cuts? In other words, how many generations before there's no measurable trace of yellowfin?
 Reply by: Wilderfish      Posted: May. 18, 5:23:05 AM     Points: 26
A few historic references such as the one below make it sound like Greenback Cutthroat were also present in Twin Lakes at the time the Yellowfin was discovered. If so wouldn't it suggest that they naturally did not cross breed with the Greenbacks? Otherwise they wouldn't have been a distinct species right?

fisheries biologist Robert J. Behnke, who commented, "I have no doubt that Jordan was correct the yellowfin trout and the greenback trout from Twin Lakes were two distinct groups of cutthroat trout".
 Reply by: Wilderfish      Posted: May. 18, 5:35:33 AM     Points: 26
Here are the two other excerpts regarding this.

In July 1889, Professor D. S. Jordan and G. R. Fisher visited Twin Lakes and published their discoveries in the 1891 Bulletin of the US Fish Commission. They found both the greenback and what they proclaimed to be a new species the "yellowfin cutthroat".

Until about 1903, greenback and yellowfin cutthroats survived together in Twin Lakes, the populations remaining isolated as both breeders and feeders. The end for the yellowfin cutthroat came soon after the introduction of the rainbow trout to Twin Lakes. The greenback population interbred with the rainbows but the yellowfin disappeared completely.
 Reply by: eholm      Posted: May. 18, 12:19:44 PM     Points: 18072
"If so wouldn't it suggest that they naturally did not cross breed with the Greenbacks? Otherwise they wouldn't have been a distinct species right?"

I'm NOT a biologist, but my understanding is - not necessarily. Since the two subspecies co-existed and remained unique, I think you are correct to assume they mostly kept their breeding to within their own subspecies during the recorded period of time we know about in Twin Lakes. However, that doesn't mean NO interbreeding took place.

We do know that cutthroat subspecies can and do hybridize. That is one of the challenges of stocking specific subspecies such as the Greenback with the objective of repopulation.

"In addition to displacement of Greenback Cutthroat via competition, Greenback Cutthroat also readily hybridized with Rainbow Trout and other subspecies of Cutthroat resulting in a loss of genetic integrity of in many populations" - [log in for link]

There are several studies that are mostly over my head, such as...

[log in for link]

[log in for link]

[log in for link] (Behnke's incredible 170 page report from 1979)

But one thing I gather from those research papers is the constant possibility of introgressive hybridization, which makes a "purebred" subspecies both difficult to identify and stock. Fisheries biologists would readily admit this, as an earlier attempt to reintroduce the Greenback was later found out to be the Colorado River subspecies ( [log in for link] ).

Another interesting gene-related challenge, was the high rate of deformities among hatchery Greenbacks from the Bear Creek strain. As a non-biologist fish-enthusiast angler, I find this particularly interesting, because they are taking fish that are potentially genetically "weaker" to replace fish that may be genetically "stronger".

Biologists say the way most of these subspecies evolved was due to geographic isolation. So I might think of it like... imagine a small colony of inbreeding rednecks hidden in an Appalachian forest. Over the decades, would they become genetically stronger or weaker?

That's not to say the preservation and reintroduction of subspecies isn't important. Like I said in an earlier post, the reintroduction of the Lahontan cutthroat is one of my favorite fish stories. Those fish are thriving. I'd love to see the Yellowfin cutty get a similar chance.
 Reply by: Wilderfish      Posted: May. 21, 8:24:06 AM     Points: 26
Thanks for the info! I'll have to dig into those research papers this week. Your analogy of the isolated rednecks is hilarious. I also don't know much about the Lahontan Cutthroat restoration story so will be researching that as well.

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