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By Joe Lewandowski
Colorado Parks and Wildlife
Colorado Parks and Wildlife biologists have discovered a unique genetic lineage of Colorado cutthroat trout in southwestern Colorado that was thought to be extinct. The agency will continue to evaluate the results and collaborate with agency partners to protect and manage populations of this native trout.
The discovery was officially recognized earlier this year through advanced genetic testing techniques that can examine the basic components of an organism's DNA, the building blocks of life. This exciting discovery demonstrates the value of applying state-of-the-art genetic science to decades of managing and understanding indigenous conservation.
"Anyone who has just watched these fish would struggle to differentiate them from anyone else but that's a significant finding," said Jim White, aquatic biologist for CPW in Durango. "Now, we will work to determine if we can propagate these fish in our hatcheries and reintroduce them into the wild in their historic habitat. This is an excellent conservation effort and an excellent conservation history. "
Eight small populations of these trout were found in the water courses of the San Juan River Basin, in the San Juan National Forest, and on private property. Populations are found in isolated habitats and are supported by natural reproduction. US Forest Service staff and landowners cooperated with CPW's efforts; they will also contribute to the pursuit of conservation efforts.
In August, north of Durango, teams from CPW and the US Forest Service entered two small, isolated coves affected by fire 416 and removed 58 fish. Ash flows from the fire could have severely affected these small populations.
Cutthroat trout originates from the Pacific Ocean and is one of the most diverse fish species in North America with 14 different subspecies. Three related subspecies are found in Colorado: cutthroat trout of the Colorado River found west of the continental watershed; Cutthroat trout in the South Platte River basin; and the cutthroat trout of the Rio Grande in the San Luis Valley. A fourth, cutthroat trout from the Arkansas Basin, disappeared in the early 1900s. The cutthroats in each of these regions have specific and distinctive genetic markers. CPW is spreading the remaining three subspecies and actively manages their conservation and recovery throughout the state.
White and other biologists – including Kevin Rogers, CPW stealth researcher based in Steamboat Springs, and Mike Japhet, CPW's retired water biologist from Durango – have been monitoring isolated coves in southwestern Ontario for more than 30 years. Colorado in search of isolated populations of cutthroat trout. They found populations in remote locations long before advanced genetic testing was available. Biologists have realized that isolated populations may have unique genetic characteristics and adaptations. They therefore made sure to keep the samples collected for subsequent genetic testing. Significant advances in genetic testing technology over the past 10 years have identified distinct genetic markers that identify the San Juan lineage trout as unique.
In 1874, naturalist Charles E. Aiken collected and stored fish samples found in the San Juan River near Pagosa Springs. Two trout were deposited at the Smithsonian National Museum of Natural History in Washington, DC These samples were forgotten until 2012, when a team of researchers from the University of Colorado was hired by the Ontario Recovery Team. Green trout to study old specimens of trout museums. When the researchers tested tissue from these two specimens, they found unique genetic markers in the San Juan River Basin. With knowledge of these genetic "fingerprints," CPW researchers and biologists set out to test all populations of cutthroat trout that they could find in the basin in search of relict populations.
"We always ask ourselves," What if we could go back to the time of pioneer colonization and widespread non-native fish stocks to see what we had here? Said White. The painstaking work done by biologists over the years, the search for these old specimens in the museum and genetic testing have allowed us to go back in time. We now have the opportunity to conserve this native trout in southwestern Colorado. "
The development of a broodstock for these trout to be reintroduced into the waterways of the San Juan River will be a key conservation strategy to increase their distribution in suitable habitat and to promote their long-term stability. term. Protecting fish from diseases, other non-native fish, habitat loss and overexploitation are important factors that will be considered in a conservation plan that will be developed over the next few years. Although it may seem long, the discovery of this fish goes back more than 100 years.
Over the decades, CPW has worked with many partners across the state to find and maintain distinct populations. Many of these efforts have been made with the help of the US Forest Service, conservation groups and private landowners. CPW is also working on projects with the Colorado River Cutthroat Trout and Cutthroat Trout Conservation Teams.
All native rat species have been affected by a variety of problems, including reduced stream flow, competition with other trout species, changes in water quality, and other changes in water quality. riparian habitat. As a result, the various types of native rats are found only in isolated-source streams. In order to ensure the continued conservation of Colorado goblets, CPW stores only native species in high lakes and streams. This storage practice began in the mid-1990s.
In collaboration with the US Forest Service, the CPW has also maintained drip traps in the source streams to prevent the migration of upstream non-native trout, to remove non-native trout and store with native trout. The conservation group, Trout Unlimited, has provided valuable assistance in many of these projects.
John Alves, a senior water biologist in the southwestern CPW region, based in Durango, said the discovery demonstrates the dedication of CPW's aquatic biologists.
"These fish were discovered because of our curiosity and concern for native species," said Alves. "We are guided by a scientific inquiry based on hard work and diligence. This is a major discovery for Colorado and shows the crucial importance of continuing our research and conservation work. "
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