Fish nursery gives endangered razorback sucker babies a fin up in survival
Imagine you’re a baby razorback sucker fish.
You start life as a tiny larva that looks like a half-inch translucent noodle. To make it to adulthood, you have to brave the big, bad Colorado River — without getting eaten.
That challenging feat has become even harder in recent decades. Dams and diversions on the river have reduced the flooding that historically created safe, still backwater pools where these little guys thrived, and the introduction of predatory invasive fish species means there are more hungry mouths out to get them.
Sam Brockdorff, a biologist with the Utah Division of Wildlife Resources, said his team started to find the tags they’d attached to baby razorback suckers in the bellies of large, sharp-toothed walleyes.
“That's kind of where the big disconnect occurs,” Brockdorff said. “We find the larva, but we don't actually find them really advancing beyond [that] into the next stage of life.”
A new project near Moab, however, is giving these baby suckers a leg, or a fin, up. It’s a fish nursery on the Scott and Norma Matheson Wetlands Preserve run by The Nature Conservancy and the Utah Division of Wildlife Resources.
It aims to artificially engineer the backwater pools that used to form more often when the river would overrun its banks.
It has everything a little wild larva born in the Colorado River could ask for. A nice, quiet pond with a channel that connects to the river, complete with a gate that opens or closes the channel’s flow and a screen that keeps larger, predatory fish out.
By 2021, crews completed construction of the pond — including a pipeline from a nearby spring to ward off summer evaporation — and the nursery was ready to welcome its first class of fish babies.
Things started off slow. In its first two years combined, only around six baby razorback suckers lived long enough to be released.
This fall, however, the nursery saw a breakthrough, releasing 51 juvenile razorback suckers back into the Colorado River.
Linda Whitham, Central Canyonlands program manager for The Nature Conservancy, said it was a relief.
“For us who have been there on the ground floor from the beginning, it's just so exciting and rewarding that we had such large numbers.”
The fish are endemic to the Colorado River, found nowhere else in the world. Since these suckers can live more than 40 years, she said, the impacts of this work could be felt in the river for a long time.
So why did the project work so well this year? All the extra flow coming downstream from the wet winter was a big help, Brockdorff said.
But the season brought extra challenges, too. The river spilled into one part of the wetland this spring, allowing some predatory fish in. He worried there may not be any razorback suckers left by fall.
When it came time to release the fish back into the river, Brockdorff and others stood in the channel, waist-deep in waders, identifying and counting the young suckers as they caught them in nets. A few inches long now, each fish got tagged with a transponder, so Brockdorff’s team will be able to track where they go from here.
It’ll be especially exciting to follow their progress, Brockdorff said, because this new generation of fish was born in the wild, unlike their parents born in hatchery programs.
“They've been experiencing predator avoidance since the day they were born,” he said. “So it's just going to be really exciting to see what these wild fish are able to do here in the future.”
The nursery pond likely won’t be this successful every year, Whitham said. It’ll depend a lot on how high the river flows. But this year’s batch of young fish shows the potential impact projects like this one can have.
Helping at least some of these fish get back into the ecosystem where they belong, she said, is a step in the right direction for repairing the Colorado River.
“[The razorback suckers] are a barometer of how healthy the river system is, and they're showing us that things are out of alignment,” she said. “We're — I hope — on the road to course-correcting by improving conditions for not just the razorback sucker, but for other organisms as well.”