ALBUQUERQUE, N.M. (AP) - When nature fails to provide, faking it might be the next best option.
Water managers and biologists have come up with a plan they think will trick the endangered Rio Grande silvery minnow into spawning this spring.
They started releasing extra water into the Rio Grande on Monday in an effort to mimic spring runoff. Under non-drought-stricken conditions, runoff would trigger the tiny fish’s reproductive instincts, but that hasn’t happened in the last few years thanks to severe drought.
“It was a tremendous effort by all involved to use what limited water that is available to help create an artificial pulse flow that we hope will trigger a substantial spawn,” said Mike Hamman, the Bureau of Reclamation’s Albuquerque area manager.
Officials are desperate since the minnow population is now at its lowest level since monitoring began more than 20 years ago.
More than 2 million silvery minnows have been released in the Middle Rio Grande since 2002 as part of an effort to recover the species. Surveys in October indicated a poor survival rate among the hatchery-raised fish that were released, and only a fraction of those captured during the surveys were wild-born fish.
Last year, the drought reached unprecedented levels in New Mexico and biologists were forced to rescue what minnows they could from isolated pools in the Rio Grande.
With little water flowing down the river, minnow management has turned into a vicious cycle that starts each fall with the release of hatchery-raised fish. That’s followed by hopes for snow and runoff in the spring and then scrambling in the summer to rescue stranded minnows with nets and buckets.
This year is expected to be no different. The flow coming into the most northern reservoir on the Rio Grande is expected to be only 28 percent of normal, according to the Bureau of Reclamation.
Thomas Archdeacon, a biologist with the U.S. Fish and Wildlife Service, said the plan is geared toward the worst-case scenario this year. The top priority is to collect the eggs that result from the spawning and get them to the hatcheries for rearing.
The semi-buoyant eggs are captured on screens that are placed in the river. The less water flowing downstream, the better the chance of collecting more eggs.
Roughly 50,000 eggs were collected last year and Archdeacon expects a similar amount this spring.
If any of the fish survive in the river through the fall, biologists and conservationists say that will be a bonus.
An exchange among several Native American pueblos and Albuquerque’s water utility authority helped make the release of water possible.
Officials say the river’s flow at the upper end of the minnow’s range - just south of Cochiti Reservoir - is expected to double this week. In all, 18,000 acre-feet of water will be used to boost flows.
Jen Pelz, director of WildEarth Guardian’s wild rivers program, said the release is encouraging but likely won’t be enough to create the overbank flows that the minnows need to rear their young. Drying of the river later in the year is another concern, she said.
“While it’s helpful for the hatcheries, the goal is to have self-sustaining populations in the river,” she said. “If you can’t keep the river wet, especially in key reaches, then that’s going to be a problem for the fish. You can’t have one and not the other.”
Federal water managers have said they hope to keep the river wet and connected through the Middle Rio Grande Valley at least through June 15.
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