The Colorado River Is Dying. Can Its Aquatic Dinosaurs Be Saved?
“You’re looking at the most endangered fish in North America,” Zane Olsen, the manager of the Ouray National Fish Hatchery, tells me as he points to a deep open-topped water tank. Inside are dozens of juvenile bonytail, the rarest of four endangered native Colorado River fish species and one Olsen and his colleagues are trying to bring back from the brink of extinction.
When I arrived at the hatchery one clear morning in May, Olsen was already soggy. Fish eggs mottled his pink polo shirt, and the tall, rangy fellow didn’t seem to have a moment to stand still. The hatchery essentially functions as a fertility clinic for fish, and this was the one day a year that it spawns the razorback sucker, another endangered fish that makes up the bulk of the hatchery work. (The Colorado pikeminnow and the humpback chub, the other two endangered Colorado River basin fish, are raised elsewhere.) Three days earlier, hatchery workers had injected the razorback with hormones to ripen their eggs, and now the team had a short window for capturing them. I’d come to help with the spawning and to learn more about how the endangered fish are faring after more than two decades of drought in the West.
Found nowhere else in the world, the native razorback has occupied the waterways of the Colorado River basin for at least 3 million years, one reason Olsen says they’re called the dinosaurs of the Colorado. Known as “detritivores,” the bottom-feeding fish were once an important part of the river’s food chain because they nosh on dead plant and animal matter that might otherwise build up and cause disease and return essential nutrients to the ecosystem. The fish have adapted to the harsh monsoon-to-drought cycles of the desert rivers that flood with melted mountain snowpack in the spring and are parched in the late summer. Razorback suckers can grow up to three feet long, weigh 80 pounds, and live for 50 or 60 years. But such geriatric monster fish are rare in the wild today.
The native fish have not fared so well over the past century since humans began trying to make the western desert bloom by damming the Colorado and its tributaries, a watershed that was once one of the most biologically diverse in North America. “They’re a bellwether for the health of the entire river ecosystem, from Wyoming to the Gulf of California,” says Taylor McKinnon, a senior public lands advocate at the nonprofit Center for Biological Diversity.
The past two years have been especially brutal, as the winter runoff has dwindled and the worst drought in the West in at least 1,200 years has pushed the Colorado River toward catastrophic ecological collapse. The plight of the razorback and the other endangered native Colorado River basin fish, says McKinnon, are “a concrete, real-world example of how climate change magnifies a whole slate of existing threats to endangered fish.”
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September 17, 2022 at 05:11AM