The razorback sucker, once the most endangered freshwater fish in America, may be removed from the endangered list today.

The razorback sucker is native to the Colorado River Basin, an ancient-looking species that can grow up to three feet long and live almost half a century. In the 1980s, conservationists found fewer than 100 of the fish alive. Researchers laid the blame on non-native game fish which had been introduced to the rivers, and on dams disrupting their habitat and causing breeding grounds to silt in.

Colorado and Utah protected the fish under law in the 1970s. In 1991, the razorback was added to the federal endangered list as most concern. In 1998, a repopulation program was created. Through conservation efforts, removal of dams, hatcheries, and careful husbandry, the current adult population today is over 50,000.

“The razorback was the most rare species we came across,” said Tom Chart, director of the Upper Colorado River Endangered Fish Recovery Program. “Today we are finding fish that originated in hatcheries and were stocked out under the program 20 years later, and they’re behaving like they’ve always been in the wild.”

Moving the species from the endangered list to merely threatened has certain benefits for the species. As an endangered species, biologists are prevented from harming individual fish for the good of the species, such as killing gravid females to harvest eggs. Threatened status would provide protections for the species as a whole while allowing those steps to be taken.

Razorback advocates oppose the change, on the grounds that the species’ numbers are not yet self-sustaining, and particularly vulnerable to accelerating climate change. They point to the fact that most released razorback populations are only increasing via hatcheries. Except in the case of Lake Mead near Las Vegas, any spawn are being consumed before coming close to breeding age.

Photo: The North Fork of the Virgin River, part of the Upper Colorado River Basin, where the razorback sucker can be found. Credit: Shutterstock