PALISADE — For millions of years, razorback sucker fish thrived in a raging, flood-prone Colorado River and were so abundant that settlers caught them on pitchforks and fed them to cows.
But over the past 50 years, the razorbacks — yellow-bellied with humped, green heads and frenzied, fleshy lips — fell victim to dams, development and voracious nonnative predators that ate them nearly to extinction.
Now they’re making a major turnaround, beneficiaries of a 25-year, $360 million government-run rescue.
The proof can be seen on the prow of a federal electro-fishing raft, which zaps up fish by the hundreds, stunning them for monitoring or removal.
U.S. Fish and Wildlife Service biologist Darek Elverud, netting mostly nonnative predators on a recent summer morning, also found suckers — which, if not eaten as babies, can grow 3 feet long and live 40 years.
“Yep! There it is!” Elverud cried, scooping up a 13-inch 3-year-old. He and crew members measured it, scanning data from a staple-sized chip implanted beneath its pelvic fin before letting the fish go. The chip data has led to a surprising discovery: Razorback suckers regularly move up to 450 miles underwater.
“Razorbacks are making a comeback,” he said, “but it’s slow.”
The recovery has reached a point scientists are calling a “critical mass.” Yet, even though razorback numbers appear to have more than doubled since 2010, questions remain about whether humans will be trapped in a role of perpetual caretakers.
The rescue program — also aimed at saving endangered Colorado River bonytail, humpback chub and pikeminnow — relies increasingly on euthanizing invasive predators. That’s a huge feat because nonnative fish populations are exploding. It means raft crews must manually remove tens of thousands of cantankerous bass, walleye and pike that Colorado and other states introduced for the economic purpose of stimulating recreational fishing.
Natural flows
The demand for every drop of water in the Colorado River — the lifeblood for 50 million people in the West — is so great that restoring natural, fluctuating flows is considered impossible. Federal biologists initially worked at simulating small floods and re-creating side-channel pools that razorbacks need for spawning and nursing, but opportunities to re-create wildness even on a small scale proved limited amid urban population growth and industry expansion. Reservoir operators do release water where possible to help fish.
“It’s pretty well-documented and widely accepted that fish do best in the natural flow regime in which they evolved. But to fully replicate the natural flow regime, we would have to undo the water development that has occurred in the Colorado Basin over the last 150 years,” Colorado Parks and Wildlife spokesman Matt Robbins said. “That’s not going to happen.”
Federal biologists rely on copious stocking, raising suckers in tanks and pond hatcheries that are the ecological equivalent of life-support systems for species facing extinction. They’ve dropped 183,945 captive-raised suckers into the Upper Colorado since 1995, averaging about 10,000 a year since 2009, federal data show.
The idea is to give suckers a fair shot at survival in the face of fierce predators equipped to swallow them whole. Captive-bred suckers can be naive and dumb, often swimming right into shadows of bass whose two rows of teeth extend all the way into their bellies.
The strategy is working.
This past year, federal biologists tasked with removing nonnatives and monitoring endangered fish on the upper Colorado found hundreds of razorbacks. The feds now estimate the population is approaching 5,800, up from 3,856 in 2010 and 1,962 in 2005. When biologists conducted a survey capturing adult suckers in the spring of 2015, they counted 1,151 — nearly triple the 419 captured in 2013.
Nobody expected a comeback. Five years ago, electro-fishing forays along this stretch of the Colorado River, 14 miles between Palisade and Grand Junction, rarely netted more than a few suckers, said Fish and Wildlife project leader Dale Ryden, who runs the hatcheries and electro-fishing operations.
“These creatures have been around only in this river for 2 million to 5 million years. They’ve seen all kinds of things — high and low flows, channel changes, wildfires. It was only in the last 50 years that we managed to nearly wipe them out with things we’ve done,” Ryden said. “We have a moral obligation to try and make sure these animals don’t go away.”
The recovery of razorback suckers would notch an exceptional success under the Endangered Species Act, which compels ecological rescues to save 1,367 animals (184 of them fish) currently listed as likely to go extinct. Only a few species classified as endangered, such as the bald eagle and peregrine falcon, have recovered sufficiently to be taken off the list. And freshwater fish have fared especially poorly. Federal wildlife officials calculated at least seven species a decade go extinct.
To make it off the endangered species list, razorback suckers would have to reproduce on their own, becoming self-sustaining. However, they could be down-listed from endangered to threatened if their numbers reach higher than 5,800 and stay there.
“They are easily on track to be down-listed,” Ryden said. “Within the last five years, we hit that critical mass.”
Yet, water depletion and the chain-reaction changes caused by dams all along the Colorado River — from headwaters in the mountains west of Denver to the desert above the Sea of Cortez — present difficult challenges.
Wandering fish
The new evidence of just how far razorback suckers wander suggests human impact on the habitat they need may be worse than previously believed.
The analysis of chips implanted in hatcheries has revealed razorbacks moving from stocking points in Utah along the Green River, a Colorado tributary, through Colorado’s Grand Valley upriver of Grand Junction as far as Rifle. Three suckers moved 350 to 425 miles between Moab and Colorado after being stocked in New Mexico on the San Juan River, federal records show. One razorback stocked in Utah on the Green River traveled nearly 500 miles to a point near Mexican Hat.
“There’s no telling how far these fish may have migrated before the big dams were constructed,” said Tom Chart, director of the Upper Colorado River Endangered Fish Recovery Program, at Fish and Wildlife regional headquarters in Denver.
The long-distance movements through different river basins are important because less than a third of razorback suckers’ original Western habitat has been protected as part of the federal recovery program, Chart said.
“This present-day movement information tells us we have got to make the most of the habitat we have left to successfully recover the species,” he said.
The feds have installed concrete ramp “ladders” and other fish passages to circumvent dams, trying to meet razorback suckers’ needs to move for spawning and raising their young.
There are hopeful signs now and then. Federal biologists observed 48 juvenile suckers hatched in the river a couple of years ago just over the Colorado border in Utah. It was evidence that stocked populations may be reproducing on their own.
Some federal officials hold out hopes that more water-flow adjustments can be made to help native fish. But the feds and state partners now are focusing on removal of the nonnative predators.
The suckers live in a rough underwater neighborhood. The numbers of small-mouth bass, walleye and northern pike populations, stocked for sport-fishing, are increasing rapidly because they thrive in the altered conditions created by dams: colder water, regularized flows and fewer side pools, where suckers can grow. And the predators are proving to be superior breeders and hunters, lurking near river banks favored by suckers and ambushing them, swallowing them whole.
“We’ve got to try to offset the threats to this species with something we can control — and that is the nonnative predators,” Chart said.
To that end, Fish and Wildlife recently installed a $1.3 million net — 250 feet wide and 30 feet deep — above the Colorado River at Elkhead Reservoir, aiming to screen out bass and other predators before they enter the main stem of the river.
They plan to put in another big net near Ridgeway in southwestern Colorado. And federal project leaders are considering how best to work with motivated sportsmen to remove more bass, walleye and pike — perhaps by pushing for a state law requiring anglers to kill any of those fish that they catch. Other states have enacted such laws to help native fish.
Manually weeding out nonnatives one-by-one on electro-fishing patrols is difficult — often in 90-degree heat, stuffing nonnatives in plastic bags where they suffocate before being hauled to landfills — but federal raft crew members say they believe it’s the right thing to do for the razorbacks.
“They have to start reproducing. They have to be self-sustaining to be taken off that list,” Ryden said on the river.
“Many are still getting eaten, or not surviving, or something. We’ve got to get their numbers up,” he said. “We’ve got adults. We’ve got larvae. But we don’t have enough of the young juveniles. That’s the piece we’re missing. We’re trying to saturation dump the system with fish, get them out there. The more pairs of breeding adults we have in the river, the more babies we’re going to have. And more babies may mean more juveniles.”
