Scientists find yearling Colorado Pikeminnow in the San Juan River

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FARMINGTON —  A fish that federal officials say was once widely known as the "salmon of the southwest" shows signs of recovering its diminished population in the San Juan River basin, according to data collected last year.

Scientists say they have found evidence that the Colorado pikeminnow is reproducing in the San Juan River, and the offspring are surviving. 

This conclusion is based on data gathered last year following the spring peak release from Navajo Dam. Scientists found more Colorado pikeminnow in the San Juan River than in previous years, according to a press release from the U.S. Department of Fish and Wildlife Services. They also found 23 yearling fish. Prior to last year, only one juvenile fish had been caught by scientists since work began in the 1990s to restore habitat.

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In a press release, Tom Wesche, a University of Wyoming professor emeritus and a member of the San Juan River Recovery Implementation Program's biology committee, said finding the young fish that had been born in the river and survived the winter is great news. He said it "hopefully represents important progress along the road to species recovery."

More than 540 Colorado pikeminnow were counted in the San Juan River last year, according to a press release from the U.S. Fish and Wildlife Service.

The Colorado pikeminnow's name can be misleading. It is not a pike, like the introduced northern pike. It is also not small, despite being a minnow. Sharon Whitmore, the San Juan River Recovery Implementation Program coordinator, said it is the largest minnow in North America and can be up to 6 feet long.

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The San Juan River Recovery Implementation Program — which includes participation by several entities, including the state of New Mexico, that are working to improve habitat in the San Juan River — is credited with helping the endangered Colorado pikeminnow recover. The program's goal is to eventually get the Colorado pikeminnow removed from the endangered species list.

Whitmore said finding the juvenile fish was a step toward reaching that goal. There are still other milestones that need to be met before the fish can be removed from the list.

There must be more than 800 adult Colorado pikeminnow and more than 1,000 juveniles in the San Juan River basin before the species can be delisted. Other criteria that must be met are listed on the program's website.

Whitmore said the Colorado pikeminnow's decline was likely caused by human development along the river, including dams, diversions and depletion of water for agricultural uses.

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"All those different changes through time just affect how rivers function," she said.

Snow melt, which increases the flow of the river, triggers the fish to spawn, but the dam at Navajo Lake has prevented large spring runoffs. When there is enough moisture, the U.S. Bureau of Reclamation increases the flow in the San Juan River to 5,000 cubic feet per second. The bureau has able to conduct the spring peak release for the past two years.

The spring peak release from Navajo Dam serves several purposes, one of which is to flush sediment from the cobble at the bottom of the river. This provides the fish with a place to lay their eggs, Whitmore said.

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The Colorado pikeminnow lives in three river basins: The San Juan River basin, the Colorado River basin and the Green River basin. Both the Colorado and Green river basins have populations of Colorado pikeminnow that are reproducing and surviving to adulthood. The San Juan River basin relies on fish stocked from the Southwestern Native Aquatic Resources Recovery Center, a fish hatchery located in Dexter that focuses on breeding endangered species, she said.

"Before dams, they would move throughout the entire system from one tributary to another," Whitmore said.

Hannah Grover covers government for The Daily Times. She can be reached at 505-564-4652.

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