Razorback suckers are hanging on in the San Juan River

From The Denver Post (Bruce Finley):

U.S. Fish and Wildlife Service biologists counted 50 yearling razorbacks during a recent survey in the upper Colorado River Basin — the result of water releases in 2016 and 2017 from the Navajo Reservoir aimed at helping the fish, agency officials said this week.

Federal operators of the reservoir let out 5,000 cubic feet of water per second for 50 days, more than doubling regular flows in the San Juan River. This increased flow created nursery pools, the habitat razorbacks and three other endangered native fish need to spawn and survive.

Saving razorbacks and other fish “is going to be totally dependent ” on putting more water into rivers, said Tom Chart, director of the Upper Colorado River Endangered Fish Recovery Program, a 25-year, $360 million government-run rescue effort.

“We’re not going to be able to restore the natural hydrological conditions. We understand that,” Chart said. “But we can recreate conditions that help young fish much more regularly.”

Yet the intensifying climate shift toward heat and aridity in Southwestern states, combined with population growth, constrains biologists’ push to put more water into rivers for environmental purposes. No water could be released this year from the Navajo Reservoir, which straddles Colorado and New Mexico and holds 1.7 million acre-feet, Bureau of Reclamation engineer Susan Behery said. Probably none will be spared next year, either, because water managers are prioritizing storage after a near-record low snow year left the reservoir half full.

Raising, stocking razorbacks

For more than 30 years, federal biologists responsible for emergency rescues of endangered species have relied on raising razorbacks in hatcheries and copiously stocking them into Colorado River tributaries. Razorbacks evolved in wild free-flowing rivers, enduring for millions of years, until widespread dams and diversions reduced and regularized nature’s fluctuating flows. The razorback had nearly blinked out by 1980 with only 100 survivors — weakened by the disruption of flows and attacked by non-native predators such as bass, walleye and pike that state wildlife agencies have introduced for recreational sport fishing…

Federal survey crews counted the 50 yearling razorbacks along the San Juan River downriver from the Navajo Reservoir. That’s the most fish counted since the surveys began two decades ago. Fish and Wildlife Service biologists calculated that this many yearlings could mean there are thousands of razorbacks along a 180-mile stretch of the river before it reaches Lake Powell.

Navajo tribal biologists have embraced the effort to save razorbacks and other imperiled native fish. A Navajo team this year helped move 300 razorbacks over a barrier for spawning while weeding out non-native predators.

“We are trying to preserve the razorback for our future generations,” said Navajo fish biologist Jerrod Bowman. “So that our kids can see razorbacks. … Our numbers are really looking great.”

“Far from the self-sustaining populations”

The problem with officially upgrading the status of fish, Bowman said, is that just the presence of yearlings may not establish that a species has become self-sustaining as required. Razorbacks usually don’t reproduce until they’re at least 2 years old. Adults can live up to 40 years.

Under President Donald Trump, federal wildlife officials have faced pressure to upgrade and de-list endangered species when scientists still aren’t certain about survival, said ecologist Taylor McKinnon, a public lands campaigner for the Center for Biological Diversity.

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