The Razorback Sucker is only found in the Colorado River and its tributaries – nowhere else in the world
Vernal, UT — Friday, May 15 The razorback sucker is an easily recognizable brownish-green fish with a bony hump on its back that is only found in the Colorado River and its tributaries — nowhere else in the world. When fully mature, this fish can reach lengths of up to 3.5 feet and live more than 40 years.
Endangered Razorback Suckers
Changes in historic river flows and the introduction of nonnative predator fish caused a huge population decline for the razorback sucker, and by 1988, the adult population of razorback suckers in the Green River was estimated at 978 and declining fast. It was listed as endangered under the Endangered Species Act in 1991.
Helping the species
The recovery of the razorback sucker began in the Upper Colorado River Basin with the establishment of the Upper Colorado River Endangered Fish Recovery Program in 1988. The program is a collaborative effort among 14 agencies that have identified ways to help the fish species recover.
The recovery program collected some of the remaining wild adults and began raising new fish in hatcheries to help bolster the population. Once they were big enough to no longer be targeted by the nonnative predator fish, the razorback suckers were restocked into the middle Green River and its tributaries, hundreds of miles of river that were federally designated as critical habitat.
To complete its life cycle, the razorback sucker travels between adult, spawning and nursery habitats throughout multiple rivers and drainages. Adult razorback suckers migrate hundreds of miles during high spring river flows to spawn. To survive and escape predators, their recently-hatched larval offspring need to drift downstream and enter into any nearby wetlands. The wetlands provide a nursery environment with quiet, warm water — and better food sources — allowing the fish to develop and grow. Having this type of habitat is critical because these small fish have few defense mechanisms at this stage, especially against predators.
Once they reach 2–3 years old, these fish spend most of their lives in deeper water, eating insects and plants on the river bottom. In the spring, as the mountain snowpack melts and the rivers rise, they return to their spawning grounds — which includes only a few locations — and start the process again.
Flooding historically existed in the Green River drainage, naturally creating floodplains that the larval fish needed to survive. But that diminished when the Flaming Gorge Dam was built in 1964, and levees built up over the decades, which also prevented the river from flooding. That combination eliminated the floodplain habitat the larval fish needed to escape predators by being washed into wetlands by high water flows each spring.
Following an extensive levee removal project where breaches were created in the 1990s, the Bureau of Reclamation altered the operations at Flaming Gorge Dam in 2006 to allow releases of water from the dam each spring to create human-made floodplains to benefit larval razorback suckers. However, after several years, biologists realized that the timing of the water flows didn’t match when the larval razorback suckers were drifting down the Green River.
Larval-triggered water releases from Flaming Gorge Dam
As a result, the recovery program began a larval trigger study in 2012. This study implements controlled water releases from the Flaming Gorge Dam by the Bureau of Reclamation each spring — once U.S. Fish and Wildlife Service biologists detect larval razorback suckers in the river, typically in May or June — and those high flow releases create the needed wetlands for the larval fish. The water releases mimic the natural flow of the Green River, but are generally lower in magnitude and duration than natural spring flows.
“The Green River flow requests are essential in helping razorback suckers and other endangered fish recover,” DWR Northeastern Region Native Aquatics Project Leader Matt Breen said. “It takes a major collaborative effort because high water flows impact so many different water users, and it just wouldn’t be possible without the continued collaboration and cooperation of our partners. Effective communication has been the key to success with this project. These high flows also benefit the river in other ways by reducing sediment buildup and building habitat for native plants like willows and cottonwoods.”
Beginning in 2012, despite being a very dry year, the water releases from the dam successfully filled the floodplain at Stewart Lake Waterfowl Management Area, a roughly 500-acre wetland area along the Green River that is managed by the DWR. That same year, the recovery program detected some wild-produced juvenile razorback sucker, showing that the larval-triggered water releases had been successful in helping the fish, while also meeting the needs of other various water users.
“Stewart Lake has proven to be an ideal place to help young razorback suckers in their historical nursery habitat because it had existing control structures that allow biologists to control how water enters and leaves the wetland,” DWR Native Aquatics Biologist Michael Partlow said. “For an additional safety measure, we also added a screen to our control structures that would allow larval razorback suckers in, while keeping out large predators like smallmouth bass and northern pike, as well as competitors like carp.”
The road to recovery
In July 2013, 592 2.5-inch juvenile razorback suckers were released in the Green River from Stewart Lake before the lake was to be drained in the fall, making it the largest number of juvenile razorback suckers documented in the Colorado River Basin since the construction of the Flaming Gorge Dam. Since then, around 4,000 juvenile razorback suckers have grown and been released from Stewart Lake. Hundreds of these fish have been inserted with special tracking tags and have been documented surviving to 3 years old, a first, since the installation of the Flaming Gorge Dam.
“I feel proud to be a part of a species’ recovery effort that is slowly, but surely, showing real success,” Partlow said. “Some people hear the word ‘sucker’ and may think it’s a worthless fish, but it’s truly a unique and important species. There is no other fish in the world that has such a unique bony ridge on its back, and they have evolved to live in a truly unique habitat.”
In October 2018, the U.S. Fish and Wildlife Service proposed to downlist the razorback sucker from endangered to threatened. Currently, there are an estimated 35,000 adult razorback suckers in the Green River, a majority of which were hatchery raised and stocked.
“It’s unfortunate that it takes so long to restore wildlife populations,” Chris Keleher, DNR director of recovery programs, said. “Once a species gets to the point that it’s endangered, it takes a huge effort, a lot of time and patience, public support and a lot of funding to get them back in shape, but we are seeing positive results. We’ve been fortunate to have partners who support this effort. Partnerships are the key to conservation effectiveness.”
All of the following agencies and organizations play a role in helping the razorback suckers:
State of Colorado
State of Utah
State of Wyoming
Bureau of Reclamation
Colorado River Energy Distributors Association
Colorado Water Congress
National Park Service
The Nature Conservancy
U.S. Fish and Wildlife Service
Utah Water Users Association
Western Area Power Administration
Western Resource Advocates
Wyoming Water Association
“The U.S. Fish and Wildlife Service’s decision to propose down listing the razorback sucker represents the power of partners working together on conservation,” Tom Chart, director of the Upper Colorado River Endangered Fish Recovery Program, said. “Our recovery program basically had to start from scratch 30 years ago as the wild populations of razorback sucker in the Upper Colorado River Basin were on the brink of extinction. Today, coordinated releases from Flaming Gorge Reservoir, coupled with proper floodplain management, are creating conditions in the river that we hope leads to self-sustaining populations in the future.”