I’m going to try and explain to the best I can from what I’ve been told about the Greenback Cutthroat topic. I had the good fortune to talk with Doug Krieger from the DOW and watch a presentation about the topic. He sent me his presentation and I am going to use a few slides that I found pretty interesting. I will add I am no way an expert on the topic, this is just my understanding.
The information they found from Metcalf’s DNA study pretty much shattered the old idea that native cutthroats caught on the western slope were Colorado River Cutthroats and fish on the eastern slope were Greenback Cutthroats. It became apparent throughout the study that stocking or transplanting of fish happened way earlier then they had thought in Colorado. The important problem with this is that the “native greenback” is supposed to be the native fish of the South Platte River Drainage.
The linage of the fish we were calling greenbacks showed it was a western slope fish…
The Colorado River linage was also shown to still be a western slope fish…
So how did these fish get to the Front Range? It was discovered that two lakes in particular were responsible for the stockings… Both pretty much in the center of the bio mass for each species listed above. Trappers Lake in the Flattops for the Colorado River Cutthroats and Alexander Lake on Grand Mesa for the fish formally known as a Greenback Cutthroat. As early as 1899 fish were being stocked from Alexander Lake, shockingly 29 million fish from 1899-1909 and on top of that 26 million from 1912-1925 from Trappers Lake area.
To determine if any fish from the South Platte Drainage (Greenback) was still around they had to find fish samples pre-1899. So they started checking the museums and found several specimens preserved in alcohol.
An interesting thing about the museum samples is it appears there were six species of cutthroats in Colorado not four like previously thought. Here is a map of the samples and where they were collected from.
The Yellow Fish of the Arkansas Drainage represent the yellow fin cutthroat trout, there were no modern representatives of this lineage and are thought to be extinct.
- The Orange Fish of the Rio Grande Basin are what we currently know as Rio Grande Cutthroats. No other samples of this fish were found in the museum samples outside this drainage.
- The Red Fish from a museum sample of two fish showed that the San Juan River drainage also had a unique cutthroat. This one really has my interest as it is presumed to be extinct since there was no modern representative in the modern samplings.
- The Green Fish museum samplings have it appearing in two basins, the Gunnison and Colorado River Basins. Because of the Geology and temperature gradients these fish may have been able to move between the two basins. Because of the Continental Divide the samples found in the Arkansas Drainage are probably from early stockings.
- The Blue Fish were found in both the Yampa and Colorado River basin, but based on historical and modern data the Yampa basin appears to be inhabited solely by the Blue Fish what we know as Colorado River Cutthroats. One thing I find curious about this is the mountain whitefish shares this range with this species of Cutthroat. Coincidence?
- The Purple Fish from the South Platte Drainage are historically what carried the name of “greenback” and is thought it will retain that name. However the only modern sampling of this fish was found in the Arkansas River Drainage, Bear Creek to be more specific.
How did they get there? It appears from a homesteader named Joseph C Jones who homesteaded 160 ac in 1874, he wanted to build an inn along the Bear Creek trail which was the only access up Pikes Peak at the time an 18 mile journey that took two days. It is thought he got the fish from Trout Creek as it was the closest stream that held fish at that time… it is also in the South Platte basin.
So you guys now know about as much as I do about the Greenback genetic testing, hope you found it interesting. The Cheyenne Mountain Chapter of TU (my local group) has been working with Rocky Mountain Field Institute and several other groups to protect Bear Creek from sediment, erosion, water purity problems, and other issues for several years and are still working in the area to protect the Creek. It is a popular location for motorcycles and mountain biking and will need these projects to keep these fish from going the way of the yellow fish and red fish. The DOW is already looking for suitable areas to stock these fish elsewhere to establish new pockets of these fish.
The whole powerpoint can be found here:
For more information on the Greenback Cutthroat Trout Recovery Team, please see:
To learn more about cutthroat conservation and research, please see: