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In October, Colorado Parks and Wildlife biologists were conducting a routine fish survey on the Colorado River when they made an . 

The crews netted not one, but three Colorado pikeminnows — one of the basin’s most critically endangered aquatic species with a history stretching back 3 million years. 

The captures took place within 15 minutes of each other and were met with screams of excitement and some surprise, according to Tyler Swarr, the native aquatic species biologist in Colorado Parks and Wildlife’s northwest region. 

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“They’re incredibly rare at this point,” Swarr said. “The last estimates I heard for the Colorado River population was that there’s maybe 800 adults left… So, for a number of the folks on our crew, we hadn’t handled or seen one in five to 10 years. Everyone was screaming, it was just so cool and there was so much excitement.” 

Swarr was in one of the boats when the discoveries were made on the Colorado River’s 15-Mile Reach — a stretch of the river between Palisade and the river’s confluence with the Gunnison River that has become critical habitat for not only the Colorado pikeminnow but several endangered native fish species.  

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What’s so special about the Colorado pikeminnow? 

Colorado pikeminnow have evolved in the Colorado River basin for the past 3 million years, tracing back to a time when wooly mammoths also roamed Earth.

The species has been known by many names including the lion of the river and white salmon, according to an .

Dale Ryden, part of the agency’s Grand Junction Fish and Wildlife Conservation Office, described the fish as almost “cartoonish looking” on the podcast.  

Want to hear something pretty darn exciting?

On Oct. 30, during the annual native fish survey on the Colorado River, aquatic biologists netted not 1 but 3 Colorado Pikeminnow!

Check out this video to see why this was such an exciting moment for CPW.

— CPW NW Region (@CPW_NW)

“Their head looks like a massive thing that’s been put almost unnaturally on the front of their long cylindrical body. They’ve got these really big, strong lips; I like to refer to them as, like, Mick Jagger lips,” Ryden said. 

Historically, the predatory fish grew to about 6 feet long, some weighing up to 80 pounds. 

Today, the species is almost half the size. The three netted in the Colorado River last fall were between 28 and 30 inches, and “pretty large and good-sized individuals” in modern times, according to Swarr. 

Part of their size can be attributed to their lengthy lifespan, with pikeminnows able to live over 50 years in the wild, . 

It also makes it the largest minnow species in the world — a family biologically defined by their toothless mouths, Swarr said. Rather, they have teeth in their throat known as pharyngeal teeth meaning eating requires that they gulp in their prey, chewing when it hits these teeth. 

While this makes them distinct from many of the other fish at the top of the food chain, “they’re a mega predator,” Swarr said. 

collected by the Fish and Wildlife Service reported using everything from swallows and mice to chunks of chicken and rabbit to catch pikeminnows — one reporting using a truck to drag the fish from the bank. Native American tribes also saw them as a prized species, the agency notes. 

The species is also super migratory, Swarr said. 

“They move hundreds and hundreds of miles to these very specific spawning areas in the basin,” he added, likening it to the travel patterns to those that salmon make. 

At one point, pikeminnow could be found “all the way from the Little Snake River in Wyoming downstream to the Gulf of California and Mexico, where the Colorado River entered the sea,” crossing various states and habitats, according to Ryden. 

Their habitat has been slashed in half. Now, they are only in the upper basin including the Colorado and Gunnison Rivers in Colorado; the Green, White and Yampa rivers in Utah; and the San Juan River in New Mexico and Utah. Spawning has been documented at two sites in the Green and Yampa rivers in Utah. 

While there have been some efforts to augment wild pikeminnow numbers in the San Juan River, all populations of the fish are currently naturally, self-sustaining populations, according to Eliza Gilbert, who works with the Fish and Wildlife Service’s San Juan River Recovery Implementation Program, on the podcast.

What are the threats facing the Colorado pikeminnow?

The Colorado pikeminnow is one of four federally listed species in the . The effort, led by the U.S. Fish and Wildlife Service, was established in 1988 to reestablish and recover populations of the pikeminnow, the humpback chub, razorback sucker and bonytail fish — all of which were on the brink of extinction. Colorado and its wildlife agency are among many of the program’s partners. 

Since its inception, the program has seen the downlisting of the humpback chub from “endangered” to “threatened” in the Endangered Species Act. The other three remain listed as endangered, but the razorback sucker has been for downlisting.

The pikeminnow was first listed as endangered in a 1967 list. Six years later, it was among the species included in the original 1973 Endangered Species Act.  

Today, among the program’s four species, the pikeminnow is the “most imperiled,” according to Swarr. 

“They’ve had really dramatic declines since the early ’90s,” he added. 

The Fish and Wildlife Service’s attributed the overall population decline to “insufficient recruitment” of juvenile pikeminnows. 

The main threats to pikeminnow populations include fishing pressure, contaminants, development and habitat loss, flow changes and, most of all, the increase of non-native fish species.

In Colorado, their “biggest threats right now are smallmouth bass, northern pike and walleye,” Swarr said.  

“We have a lot of predatory fish in the basin that are non-native or invasive species that prey upon juveniles,” he added. “So it’s really challenging for a young pikeminnow to make it to an adult at this point.”

Much of the work that Parks and Wildlife does toward the conservation of the pikeminnow and other native species supports keeping these non-native fish out of the Colorado River. This includes programs to screen sport fish stocked in reservoirs and lakes to prevent them from making it to the rivers and tributaries as well as stocking with sterile fish. 

Ryden referred to these threats as “death by a thousand cuts.” 

“Any one of these things, or a couple of these things, they could probably deal with on their own, but when you put them all together, it really gets to be this huge quandary of a problem because things pile on top of each other and you get these synergistic effects between them,” Ryden said on the podcast.  “So I think there are a lot of good things happening management wise with the recovery programs to help these fish, but there’s a lot of things that continue to plague these fish that we can’t even really begin to touch.”

Work in the 15-Mile Reach — where the pikeminnow were recently spotted by Parks and Wildlife — has been a centerpiece of the program’s efforts in the Upper Colorado River Basin. Over the past 20 years, partners have in this stretch, restoring habitat that is critical to pikeminnow, bonytail and razorback suckers while balancing local agriculture and municipal water needs. 

“The Upper Colorado River Endangered Fish Recovery Program leases quite a bit of water and spends quite a bit of money on just trying to keep water in that reach,” Swarr said. “What (catching the three pikeminnows) suggests is that by paying that premium for that water, it really is valuable for maintaining a winter holding habitat for these endangered fish.”

With continuing threats to the pikeminnow, the halting of current recovery programs would likely “result in the species becoming functionally extirpated across the range,” the 2023 recovery plan warns. 

“We’re trying to protect them and the value they bring to the Colorado River Basin,” Swarr said. “They don’t exist anywhere else in the world.”