You don’t have to be an avid angler or an aquatic biologist to be excited by the announcement from Colorado Parks and Wildlife that a unique species of cutthroat trout – native to the San Juan River drainage and long presumed extinct – has been rediscovered.
The San Juan cutthroat is one of many cutthroats native to Colorado but isolated over eons by changes to their waterways wrought by geology and glaciers.
Each major river basin in the state developed a unique subspecies, including the Greenback cutthroat of the Platte River drainage, the Rio Grande cutthroat and the Colorado River cutthroat.
The Yellowfin cutthroat, native to the Arkansas River drainage, is now believed to be extinct.
But so was the rediscovered San Juan cutthroat, positively identified through genetic testing and comparison with a pair of fish collected from the San Juan near Pagosa Springs in 1874 and preserved at the Smithsonian in Washington, D.C.
Most closely related to the Colorado River cutthroat, the San Juan trout is evidence, said Trout Unlimited’s Southwest Public Lands Coordinator Garrett Hanks, that the San Juan River was once composed of cold-water fish habitat for its full 380-mile length to its confluence with the Colorado.
“The San Juan cutthroat may once have occupied the entirety of the San Juan Basin – from the creeks above Silverton to the stretch known as the ‘quality water’ in New Mexico,” Hanks said.
“We (may) never know their historic extent, but we are now responsible for their future existence.”
Wisely, Colorado Parks and Wildlife is not disclosing just where the remnant populations of San Juan cutthroats are located.
Some of the fish have also been moved to the Durango hatchery in hopes of developing a brood stock that can be used to re-establish the fish into more areas of its original range.
The tale of the San Juan trout echoes the rediscovery of another of the West’s iconic cutthroat subspecies, the Lahontan cutthroat of Nevada.
John Fremont’s expedition to map the Great Basin in the 1840s named the Truckee River the “Salmon-Trout River” for the giant Lahontan cutthroats that ran up the river from Pyramid Lake to spawn.
The fish were decimated by commercial fishing and water diversions and dams on the Truckee, and while a related cutthroat was raised in hatcheries and stocked in the lake, the original Pyramid Lake fish, one with the ability to grow as large as 40 pounds, was believed extinct.
A century later, genetic testing on Lahontan cutthroats found in a small stream near Pilot Peak, in far eastern Nevada, confirmed the fish were direct descendants of the original Pyramid Lake fish.
Their offspring, which have retained the ability to grow as large as salmon, are now back in their home water.
“Careful work over the years by biologists … gave us the chance, essentially, to go back in time,” said CPW biologist Jim White.
And now forward, too – enriched by this gift of rediscovery.
