The humpback whale, a fish native to the Colorado River whose survival has been threatened by the construction of massive dams and the introduction of alien predators, is officially no longer at risk.
The US Fish and Wildlife Service announced on Friday its decision to reclassify the large silver minnow with the bump behind the head from endangered to endangered.
The change does not remove most of the conservation measures under the Endangered Species Act, but it does reflect that the agency no longer considers the Grand Canyon to be of imminent threat to extinction in its entire range. This area extends up and down the river basin to the Yampa River in northwest Colorado.
The announcement said the chub now numbers around 12,000 fish on the Little Colorado River, a tributary that flows into the Colorado in Grand Canyon National Park and provides refuge from the unnaturally cold and clear water that emerges from the Glen Canyon Dam in the Mainstem River flows. That compares to about 2,000 to 3,000 fish that swam in this population in the early 1990s.
Upstream, in Utah’s Westwater Canyon, the agency attributes conservation efforts over the past 15 years to establishing a population of around 3,000 chub. In the Moab area, for example, government biologists have worked to isolate chubs from predators as soon as they enter the side channels to spawn. Similarly, the National Park Service at the Grand Canyon is using electric shocks to stun fish in Bright Angel Creek and remove the non-native trout that compete with or eat chub.
The chub first landed on the Endangered Species List in 1967, four years after the completion of Glen Canyon Dam rocked the world. It has also been reduced by other dams, including the Hoover Dam downstream and the Flaming Gorge Dam upstream.
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Humpback whales evolved in warm, muddy waters. They can grow a foot or longer there, but cold, clear water in the Grand Canyon can stunt their growth and make them vulnerable to predators. Biologists have intervened to manage them intensely, sometimes even moving young chubs to a hatchery for safekeeping until they could be released in new areas around the canyon.
“The reclassification of this distinctive fish from endangered to endangered is the result of many years of collaboration between conservation partners,” said Matt Hogan, acting Regional Director of Fish and Wildlife, in a written statement. “We thank everyone involved for their efforts to address the remaining challenges in the Colorado River Basin.”
These challenges remain daunting, especially as the area’s drought is lowering the water level behind Glen Canyon Dam in Lake Powell. The sinking water threatens to warm the Colorado in the Grand Canyon, which could be good for Chub, but also terrible for them. Over Lake Powell, warm water invaders like the perch feed on chub. If warmer water welcomes them to the Grand Canyon, it could reverse progress in Little Colorado and for a growing chub population in the park.
A technical working group advising the government on the management of Glen Canyon Dam met this week to discuss ways to add more cold water to the river in case perch or other intruders gain a foothold. One idea is to install hydropower turbines in the bypass pipes of the dam, which draw water from deeper, colder areas of the reservoir than the existing power plant uses. That would offset some of the lost hydropower revenue if biologists requested a cold water shock, but it would also reduce the amount the bypass pipes could deliver.
Cold water would challenge the local fish, but it could be better for them than facing the perch, pikeperch, and other voracious fish-eaters that thrive upriver in Utah, Fish and Wildlife Service biologist Kirk Young told his colleagues at virtual meeting of the working group.
“The stakes are pretty high based on the lessons learned from the upper pelvis,” he said.
Hot water predators aren’t the only threats biologists pursue in the national park and the Glen Canyon National Recreation Area. Brown trout – another alien species that can feed on chub – breed on the Lees Ferry stretch of the river below the dam. There, state and federal fisheries officials have paid a reward to the anglers they catch and kill this year, though the effect has not yet suppressed them.
A biologist reporting to the working group said that annual trout survey trips at Lees Ferry have shifted in recent years from catching nearly 100% rainbow trout (a less fearsome intruder) to more than a quarter of the time now.
Not everyone celebrates the change in status of the chub.
“This is a political choice, not an environmental choice,” said Alicyn Gitlin, program manager for the Sierra Club’s Grand Canyon.
The fish and wildlife service took advantage of the chub’s precarious status to argue against a recent proposal to dam the Little Colorado for hydropower, Gitlin said. Although this threat has subsided, others, including pumping from upstream sources, are still present. The agency added chub based on a growing population in Little Colorado, she said, even though “we see a different threat there every few years.”
“I don’t think they have produced any evidence that it no longer qualifies for exposure,” Gitlin said.
The fish’s threatened status still prevents people from killing it and keeps the weight of the legal Endangered Species Act behind its conservation. The change gives states or other conservation workers who work with fish some new flexibility, e.g.
By definition, an endangered species is one that is likely to be endangered, while an endangered species is one that is already in immediate danger of extinction.
Brandon Loomis covers environmental and climate issues for The Arizona Republic and azcentral.com. Reach him at [email protected].
Environmental reporting on azcentral.com and in the Arizona Republic is supported by a grant from the Nina Mason Pulliam Charitable Trust. Follow the Republic’s environmental reporting team at environment.azcentral.com and @azcenvironment on Facebook, Twitter and Instagram.
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