Endangered fish reproducing in San Juan River
FARMINGTON — Biologists captured more yearling razorback suckers this fall in the San Juan River than they have captured in one season in more than 20 years, according to a press release from the U.S. Fish and Wildlife Service.
The findings in the San Juan River this spring signify the fish are reproducing in northwest New Mexico.
“It was amazing to see these little fish in the river,” said U.S. Fish and Wildlife Service biologist Nate Franssen in the press release. “We have been stocking razorbacks and managing the river for many years hoping to see these signs of recovery. It’s a ‘Field of Dreams’ moment: build the habitats and they will come.”
In 1991, the razorback sucker was classified as an endangered species under the Endangered Species Act. It is endemic to the Colorado River and its tributaries, including the San Juan River.
The announcement that the razorback sucker is reproducing in the San Juan River comes about a year after the U.S. Fish and Wildlife Service announced that another endangered fish, the Colorado pikeminnow, is showing signs of recovering in the San Juan River in New Mexico.
The fish’s population was depleted as dams were installed in the Colorado River basin, water was withdrawn for various purposes and non-native fish were introduced.
Biologists find 50 yearling razorback suckers
During the fall, biologists caught and measured fish in the San Juan River to examine the populations.
According to the press release, 50 yearling razorback suckers were caught. Biologists surmised the 50 yearling fish indicate there could be thousands of razorback suckers in a 180-mile corridor. In addition, this is the second time in more than 20 years that yearling razorback suckers were captured during the fall, according to the press release.
This means the razorback suckers' populations are likely larger than they have been in more than 20 years.
San Juan River Basin Recovery Implementation Program helps create habitat for fish
The San Juan River Basin Recovery Implementation Program has been focused on improving habitat for the endangered fish. This includes ensuring the San Juan River maintains a minimum flow level during the summer months and releasing water from Navajo Lake each spring to mimic the snowmelt from the Colorado mountains.
In addition to improving fish habitat, this program mitigated the drought-impacts San Juan River water users saw this year. While the Animas River became almost dry, the San Juan River maintained a decent flow throughout the summer.
The U.S. Fish and Wildlife Service credits spring releases from Navajo Lake for the population growth. In spring 2016 and 2017, the U.S. Bureau of Reclamation released more than 8,000 cubic feet per second from the reservoir to create fish habitat, according to the press release.
These water releases scoured the channel and created the slow-flowing, warm backwaters that young razorback suckers need, according to the press release.
Other efforts relocated adult fish upstream
In addition to the 50 yearling razorback suckers caught by biologists, Navajo Nation biologists moved about 300 adult razorback suckers over a migration barrier. Researchers led by the Bureau of Reclamation also moved hundreds of adult fish upstream of a waterfall on the San Juan River near Lake Powell, according to the press release. This was done because the razorback sucker migrates upstream each spring to spawn.
“This is likely the first time in decades that the San Juan River has supported these fish through their most vulnerable period in their life: from egg to hatching to a fall yearling,” said Franssen.