A Nursery for Endangered Fish
In the perfect spot on the Colorado River, we're blending science and engineering to give razorback suckers a fighting chance.
For the Colorado River’s endangered razorback sucker, survival to adulthood is a struggle. The fish—which sports a tell-tale, sharp-edge hump behind its head—can live up to 40 years. Instead, today most don’t live past their first year.
At TNC’s Scott M. Matheson Wetlands Preserve near Moab, Utah, scientists and engineers are giving nature a boost. Taking advantage of the preserve’s location along the Colorado River, the team plans to bring razorback sucker larvae into the preserve’s sheltered habitats in late spring, where they will be protected during their most vulnerable stage of development.
Engineers will widen the river channel, allowing the water and larval razorback suckers to enter the preserve, floating through a control gate and into the central pond. After several months of safely growing in the preserve’s pond, the more mature fish will be released back into the river’s mainstem in early fall.
The goal for this project? Restore what has been disrupted on the river through years of human impacts, and re-establish a wild, self-sustaining population of an endangered species.
A River Forever Changed
More than 100 years ago, razorback suckers thrived throughout the Colorado River Basin, at home in the swift waters of the free-flowing rivers in seven states and Mexico. They often migrated hundreds of miles in one year and grew up to 3 feet in length. But then the Colorado River entered a new era: one of dam building, increasing water withdrawals and sport fish stocking. Like other native fish, the razorback suckers began to die off, veering toward extinction as the Colorado River’s flows and habitats were altered.
Climate change—and its deepening impacts on the entire Colorado River Basin—hasn’t helped. Intensifying high temperatures and on-going low precipitation have caused river levels to drop steadily, with predictions even more dire for the future. “We used to say it’s a drought,” Taylor Hawes, TNC’s Colorado River Program Director, told the Durango Herald last summer. “After 19 years, we can say this is a pattern and trend that is punctuated by super dry years like 2002 and 2018.”
The sad reality is that for many native fish like the razorback sucker, the Colorado and its tributaries are drastically less livable.
It's a Hard-Knock Youth
Since 1991, when the razorback sucker was placed on the Endangered Species list, conservation partners and state and federal agencies have been working throughout the Colorado River Basin to bolster populations. One key challenge is getting the fish in the wild to survive past their larval and juvenile phases. For reproduction and the first year of life, razorback suckers need slow-moving, back-eddy waters—a type of habitat that has been dramatically reduced along the Colorado as dams change flow dynamics and invasive plants crop up along river banks. To make matters worse, over the past 100 years, more than 70 non-native fish species have been introduced into the Colorado River Basin, many as sport fish. These invasive species wreak havoc on the river’s native ecosystem. Razorback sucker eggs and juveniles are easy prey for toothed non-native predators.
Discovery at the Matheson Preserve
A few years ago, at TNC’s Scott M. Matheson Wetlands Preserve along the Colorado River near Moab, biologists made an exciting find while sampling for native fish. They uncovered a surprising number of wild-born razorback sucker larvae along the shoreline of the preserve. In fact, the scientists concluded the Matheson Preserve provides the only suitable nursery habitat for this species along 65 miles of the river. Encouraged by these findings, and the prospect that there could be a way to help these fish reach adulthood in the wild, TNC joined forces with the Utah Division of Wildlife Resources, Jones and DeMille Engineering, and PE Engineering to transform the preserve’s central pond into a protective nursery habitat for the fish.
Inspired by a similar effort on the middle Green River near Jensen, Utah, the team of scientists and engineers developed a plan to modify a portion of the preserve’s wetlands by widening an existing channel from the Colorado River to the preserve’s central pond. This will allow more water into the preserve during spring runoff—the time when the larvae need a safe place to grow.
Engineers have designed a control structure to channel both the water and the razorback larvae into the preserve. They are also exploring strategies to bring in alternative water sources to ensure the baby fish have enough good quality water during their three-month stay.
“This unique control structure will be the key to our success,” said Ryan Jolley, PE Engineering Project Manager. “It will have a specially designed concrete channel with a control gate and screen system that will only allow larval fish to pass while keeping larger non-native predatory fish from entering. The structure will also have a fish capture area where the young fish can be measured and tagged before being released back to the Colorado River.”
Prior to the introduction of any razorback sucker larvae, the team will drain the Preserve’s central pond to remove non-native fish that entered the wetland as larvae during the previous year. Large machinery will also deepen the pond to provide more habitat and optimize water quality.
With construction partially complete, and the river flowing high in spring 2019, TNC and its partners have already spotted the first fish larvae arrivals! “This is so exciting,” said Whitham. “Experts have identified some of these tiny, noodle-like larvae as razorbacks, which means our project design seems to be functioning as intended.” After developing safely in the nursery, the team will release the young fish into the river in the fall of 2019, with their survival odds much improved.
This fish nursery—the first on the Colorado River—could become a proven solution to help other threatened or endangered fish recover in western rivers.
Hope for the Future
In October 2018, the U.S. Fish and Wildlife Service recommended the razorback sucker’s protection status be changed from endangered to threatened. While this decision is not final and will be analyzed over the next year, the move is a testament to the collaborative and creative recovery efforts like those now unfolding at the Matheson Preserve.
Patrick McCarthy, the Deputy Director of the Colorado River Program, has led projects on the San Juan River to help save the razorback suckers. This fall, McCarthy told the Moab Sun News: “If the razorback sucker is reclassified from endangered to threatened as the U.S. Fish and Wildlife Service is recommending—it’ll mean that the collaborative efforts of water users, federal and state agencies, and tribes have brought this species back from the brink of extinction in less than the lifespan of a single fish (about 40 years)—a remarkable achievement for such a wide-ranging, long-lived species.”
Still, with climate change impacts reaching far downstream and demands on the Colorado increasing, the road to recovery for fish like the razorback suckers remains tenuous.
“We need to see these fish able to reproduce and reach adulthood successfully in the wild,” said Whitham. “That’s why scientists are working so hard on projects like our nursery at the Matheson Preserve.”
TNC extends special thanks to the Department of Natural Resources Endangered Species Mitigation Fund Recovery Program, the Utah Watershed Restoration Initiative, the Utah Department of Transportation Mitigation Fund, and the Utah Division of Wildlife Habitat Council for their lead financial support on this project.
And stay tuned for updates as this endangered species rescue plan unfolds.