64: Greenback Cutthroat Trout

I write to you from Arapahoe, Ute, and Cheyenne land. I am interested in learning about the different animals that live in the place where I was born. Before we start with today’s animal, I want to emphasize that biological classification as understood by western society has its roots in racism, sexism, and transphobia – here’s a good explainer about why.

There are not a lot of native fish in Colorado. The Colorado State University list of animals that I am using to write this newsletter has something like 44 fish on it, and so many of them are non-native, invasive species who have come into the state and often destroyed habitat or eaten native fish. Meanwhile, our native fish have been heavily impacted by things like damming of rivers, agriculture, and toxic mining processes. One of these is our official state fish, the Greenback Cutthroat Trout (Oncorhynchus clarkii stomias).

They once flourished in the icy waters of the Arkansas and South Platte Rivers in northeastern Colorado and southeastern Wyoming. Their evolution, as far as we understand it, is remarkable: their ancestors migrated up the Snake and Columbia Rivers, into the Green and Yellowstone Rivers, and then, sometime around 20,000 years ago, crossed the high peaks of the Continental Divide when it was locked in the ice age via glacial floods and became its own species on the eastern side of the Divide. For millennia, the fish thrived in the icy waters high in the mountains and foothills above the area where Denver and other Front Range cities are today. And then Euro-American settlers arrived in the late 1850s-1860s, drawn by the allure of Colorado’s mineral resources, and quickly destroyed the fish population. By the 1930s, people believed that they had gone extinct, but they were found again in 1957 in Rocky Mountain National Park and conservation efforts began there that continue to this day.

Fascinatingly, the first efforts to do so – taking place from 1957 through several decades – did not actually save the fish at all. Instead, scientists mistakenly stocked similar species of fish. In 2012, a PhD student named Jessica Metcalf published work showing that there was only a single surviving population of the actual Greenback Cutthroat Trout species, and that all the ones that that had been painstakingly restocked throughout Colorado over 30 years were actually an invasive species themselves.

The single surviving population was found in Bear Creek, near Pikes Peak, west of Colorado Springs. From the venerable High Country News:

“For years, fish biologists had been mystified by this unusual trout and had nicknamed the stream “weird Bear Creek.” No one knew what type of trout it was or where it had come from until, on the heels of the Metcalf studies, Kennedy pored through old newspaper articles, books, records, and even old diaries and letters to piece together the fish’s journey.

“After more than five years of research, Kennedy concluded that Bear Creek was historically fishless. The greenbacks had been stocked sometime after 1874 by a man named Joseph C. Jones. Jones had come to Colorado as a prospector during the gold rush and later built an inn for the hordes of tourists that visited Pike’s Peak. There he built a series of fish ponds for guests, where it is believed he stocked the greenback far outside of its native range.

“It was human stocking — the same practice that had killed off or pushed out so many of Colorado’s native trout — that had accidentally preserved the greenback.”

Conservation efforts for the Greenback are ongoing, and it is not clear if our state fish will survive.

The above High Country News article goes on to describe the current efforts to repopulate the eastern slope of the Rockies with the real version of the Greenback and is well worth a read. Also there’s a photo that will make caviar lovers very hungry. The article also made me aware of a museum in Leadville dedicated to the National Fish Hatchery there which is described: “Built in 1889, the hatchery was once considered the “most magnificent building in western Colorado,” with a wraparound Victorian porch, vaulted wood ceilings, and fish tanks made of redwood imported from California.” I will definitely be visiting that museum once lockdown is over!