Utah Division of Wildlife Resources biologist Sam Brockdorff holds a native razorback sucker before tagging and releasing it into the Colorado River. Photo by Katie Creighton/DWR
Native fish boomed around Moab this year, data suggest
High water likely helped razorback sucker, Colorado pikeminnow populations.
If you asked Katie Creighton in May how native fish would fare this year, “cautiously optimistic” might have been her answer. Spiking flows across the Colorado River basin, the result of last winter’s strong snowpack, were setting the stage for the river’s small cadre of endangered and threatened fish.
Six months later, the optimism has become less cautious.
“Now, we can put a big exclamation point on that,” said Creighton, the native aquatics project leader for the Moab office of the Utah Division of Wildlife Resources.
Indeed, counts from this year suggest that at least two endangered fish species — the razorback sucker and Colorado pikeminnow — saw a bumper season around Moab. It’s at least partly due to the spring inundation that flooded the Scott and Norma Matheson Wetlands Preserve.
“We entrained a whole bunch of water in here,” said Creighton as she gestures to a gated channel in the wetlands on a recent chilly afternoon. The channel connects the Colorado River with the preserve’s central pond, which the division has been targeting as a razorback sucker sanctuary.
“We tentatively had razorback sucker in here, but we never trapped within the wetlands, so we didn’t know for sure,” she said.
In late October, however, Creighton’s crew released fish from the pond and notched a mind-boggling count of 51 juvenile razorback suckers. In the project’s first two years, they found only four.
Creighton said members of the crew, called “fish squeezers,” also found solid numbers of young Colorado pikeminnow in nearby stretches of both the Colorado and Green rivers.
“I’m pretty thrilled at what we found this year,” Creighton said.
Raising the razorback
Bolstering Moab’s population of razorback suckers is exactly what Creighton and her team hoped for with the wetlands project.
First used in 2021, the gate-and-channel setup enables fish squeezers to control the flow of water between the Colorado River and the wetlands’ central pond, a panoramic spot ringed by tall grasses. The project was a coordinated effort between DWR and The Nature Conservancy, which manages the 900-acre area.
“The idea is simulating the floodplain inundations that would happen historically,” said DWR biologist Sam Brockdorff.
This year’s high flows provided the perfect chance to make that happen. Measured at the U.S. Geological Survey’s Cisco gage, the Colorado River peaked above 40,000 cubic feet per second (cfs) in mid-May. That was perfect for the fish squeezer crew, which left the gate open for native fish all spring.
As the peak began to subside in June, the DWR crew closed the gate entirely to secure what they hoped was a healthy crop of young razorback suckers in the wetlands’ warm, nutrient-rich waters.
“From there, we just keep the water in here as long as possible,” Brockdorff said. “Throughout the season, we check water quality, making sure that there’s no potential for fish die-off.”
The other benefit of the fish gate is excluding non-native swimmers such as carp and smallmouth bass that compete with native fish for resources and sometimes directly prey on them. The gate is gridded with a tight screen that, even when open, keeps out anything bigger than the young razorbacks.
“Non-native exclusion is something that was really important to this design,” Creighton said. “Because we didn’t want to have baby razorbacks competing with adult or large-body non-natives.”
This year, however, the river was so high that it still breached the pond from the south, Creighton said. With the water came non-natives such as gizzard shad, bass and carp.
“I was coming out here and you could see and hear all the adult carp splashing around,” said Brockdorff, standing by the now-shrunken pond.
Though that’s an issue Brockdorff and Creighton said they want to fix in future years, it also makes the high numbers of razorback this year even more remarkable.
“This is only the third season of it in full swing, so we’re still learning a lot along the way,” Brockdorff said.
Filling in the gaps
While Creighton and her crew know juvenile razorback like warmer, quieter waters, the scientific community is still figuring out exactly how to restore the endangered fish.
From left, DWR biologist Sam Brockdorff and native aquatics technicians Talitha McGuire and Teal Cummisk “electrofish,” or temporarily stun fish to collect and tag them, near the gate in the Matheson wetlands. Photo by Anna Amidon/UDWR[/caption]
“The tricky part is that we don’t know a whole lot about their life history and habitat needs,” Creighton said.
The fish, which can live up to 40 years and grow over 3 feet long, once saturated the Colorado River and its tributaries. But human activities in the 20th century — mainly dam-building — fragmented and altered the fish’s habitat. In 1991, it was listed as an endangered species.
“They became imperiled before we started to learn about them,” Creighton said. “And so we’re kind of playing catch-up in terms of how to recover the species without knowing that much about them.”
The hope is that the wetlands can provide sanctuary for juvenile razorback suckers, which Brockdorff and Creighton said seem to be lacking in the Green and Colorado rivers near Moab.
“We find larval [baby] razorbacks, but then we don’t see them beyond that,” Brockdorff said. “That’s where there’s a bottleneck occurring.”
This year provided positive signs that the wetlands can prove a potent ally for the razorback, especially coupled with natural flow regimes. In addition to finding 50-plus razorback in the wetlands, the fish squeezers located two this year in the river itself — a rare find.
“I don’t think it’s a far stretch at all to say that they benefitted [from high water],” Creighton said. She and Brockdorff noted that because razorback suckers have such long lifespans, they manage OK with occasional high flows.
“They don’t need a good year every year,” Brockdorff said.
According to Creighton, Matheson is the only wetland area managed for native fish on the Colorado River in the upper basin. The razorback coming out of the wetlands are particularly remarkable because most razorback in the basin are currently raised in hatcheries.
“We do have this small amount of wild-spawned razorback sucker that are now in the river, and some of them are coming out of Matheson,” Creighton said.
Plus, razorback weren’t the only fish that seemed to do well around Moab this year. Creighton said her team also found high numbers of Colorado pikeminnow, another endangered fish. They notched above-average catch rates on nearby stretches of the Colorado and Green rivers.
“We’re hopeful that this indicates a strong cohort of young pikeminnow coming out of 2023 and heading into their first winter,” Creighton said. “We can’t wait to encounter these little cuties in the river again and monitor them as they grow up.”
While Creighton said there’s still plenty of data analysis to conduct, the sheer numbers of pikeminnow and razorback sucker were a real treat for the fish squeezer team, especially finding them months after the Colorado River’s flows subsided.
“Stoke is high,” Creighton said. “It was a great way to end the season.”