Greenback cutthroat trout
Colorado's state fish, one of two native cutthroat trout in Rocky Mountain's streams, nearly wiped out by a century of stocking other fish.
Greenback cutthroat trout at a glance
Oncorhynchus clarkii stomias GREEN-back KUT-throht trowt; Oncorhynchus clarkii stomias is on-koh-RIN-kuss KLAR-kee-eye STOH-mee-us
- Type
- Fish · trout
- Diet
- Carnivore
- Lifespan
- Cutthroat trout as a group live around 6 to 8 years, depending on the subspecies.
- Conservation
- Threatened
Eats aquatic insects, other small invertebrates
It is a coldwater trout that feeds in clear mountain streams and lakes. NPS names it as one of the two fish species native to Rocky Mountain National Park.
Should you worry?
None. It's a fish, not a hazard, though all native cutthroat trout in Rocky Mountain are catch-and-release only. A kid who catches one should keep it wet, unhook it gently, and let it go.
A bucket of grayish-green fish waits creekside, each one about to be poured into water that hasn’t held its own kind in decades. That is what greenback cutthroat trout recovery looks like at Rocky Mountain today: a hatchery-raised fish going back into a stream it once owned before anyone stocked anything else there at all.
The stocking that made this necessary ran from 1886 to 1968, more than 20 million fish poured into Rocky Mountain’s waters, mostly species that had never lived there and that outcompeted the two native cutthroats, greenback included. The greenback was assumed gone from most of its range for decades, until a 2012 genetic study of century-old museum specimens turned up an odd twist: the only fish left anywhere with pure greenback ancestry were swimming in Bear Creek, a small stream outside the park, and they were there because an early hotelier had stocked them in a pond at the creek’s headwaters in the 1880s, to help promote a tourist route up Pikes Peak, the study’s authors reported. The same era that nearly erased the greenback had also, in one overlooked stream, saved it.
Now it’s Colorado’s state fish and a federally threatened species, and Rocky Mountain’s own Poudre Headwaters Project is working to give it back real ground: clearing competing fish from park streams so hatchery-raised greenbacks, poured out of a bucket one release at a time, have historic water to call their own again.
Did you know?
- The greenback cutthroat trout is Colorado's state fish and a federally threatened species.
- Between 1886 and 1968, more than 20 million fish were stocked into Rocky Mountain's waters, mostly non-native species that outcompeted the park's native trout.
- A 2012 genetic study of century-old museum specimens found the last population with pure greenback ancestry surviving in Bear Creek, a stream outside the park, descended from fish an early hotelier stocked there in the 1880s.
Common questions
Is the greenback cutthroat trout endangered?
It's listed as federally threatened. It's also Colorado's official state fish.
Why did Rocky Mountain's native trout nearly disappear?
Between 1886 and 1968, more than 20 million fish, mostly non-native species, were stocked into the park's waters, and they outcompeted native trout like the greenback.
Can you catch and keep a greenback cutthroat trout?
No. All native cutthroat trout in Rocky Mountain National Park are catch-and-release only.
How was the greenback cutthroat trout almost lost, and then found again?
A century of fish stocking nearly wiped it out across its original range. Then a 2012 genetic study found that fish a hotelier stocked into a pond at the head of Bear Creek in the 1880s, to help promote an early tourist route up Pikes Peak, were the last population with pure greenback ancestry.
What eats a greenback cutthroat trout?
For cutthroat trout as a whole, larger fish and wading birds such as herons eat the young. Bears catch adults.