Critically endangered silvery minnow – welcome back

The critically endangered Rio Grande Silvery Minnow (Hybognathus amarus) by the thousands are being reintroduced this week. Biologists braved the cold and snow as they loaded thousands of Endangered Minnow Releaseendangered minnows into trucks for a 12-hour trip to Texas, where the tiny fish will be released into the Rio Grande near Big Bend National Park. Between 400,000 and 500,000 minnows were being taken from the breeding facility at the biopark and a fish hatchery in southeastern New Mexico to the Big Bend area. The fish were riding in special tanks in trucks equipped with monitors and oxygen. This release has been in the planning for years.
“For us, it’s historic,” said Chris Altenbach, the biopark’s curator of fishes. “For us, this is what we’re interested in seeing, that the fish do well.”
Once the minnows get to Big Bend, they will be placed in holding pens in the river so they can acclimate. There are two release sites within the park’s boundaries as well as one upstream and one downstream.
Biologists expect to open the pens and let the minnows explore more of their new home on December 19, 2008. Keep them in holding areas helps decrease the trauma to the fish.  Their first instinct is to swim down river as fast as they can.”
Remshardt said this week’s work has been in the planning stages for years. As part of the minnow’s recovery plan, the Fish and Wildlife Service hopes to establish at least three stable population including the one in central New Mexico.
“To have a chance at making it, we have to have multiple populations and the more we have, the less pressure it puts on any one by itself,” Remshardt

One of the ways the Rio Grande Silvery Minnow eats invasive algae and other small plant and small invertebrate in the water helping keep the water clean. One of the most endangered fish in North America, according to the U. S. Fish and Wildlife Service (USFWS) it is found in less than 7 percent of its original natural habitat, the Rio Grande River. Historically, the minnow was found from Española, New Mexico, to the Gulf of Mexico in Texas. Now it can only be seen between the Cochiti Dam and the Elephant Butte Reservoir on the Rio Grande about 174 mile and  is fragmented by three river-wide dams.

It is a stout silvery minnow with moderately small eyes and a small mouth. Adults may reach 3.5 inches in total length. They also spend much of their lives laying eggs. The Rio Grande Silvery Minnow’s eggs hatch in about 24 hours into larvae that can swim in just 3 to 4 days. It is no surprise that a species so programmed for survival once dominated a biological niche that spanned 3,000 meandering miles (4,825 kilometers) from New Mexico to Texas. The minnows eggs and small size make it important as food for larger fish in the river and streams.

The population decline of the Rio Grande Silvery Minnow has been almost directly proportional to recent altercations to the Rio Grande river over the past century. There have been multiple diversions for municipal and agricultural use; alteration of the natural hydrograph (no spring runoff to cue spawning); habitat degradation from river narrowing and canalization; and construction of diversion dams which prevent migration.

“Good luck to the biologists and the fish of the Rio Grande. Thanks. “- Mother Nature


Rare New Mexico fish to swim free in Texas –  SUSAN MONTOYA BRYAN  A P – Dec 16, 2008

as quoted in

image courtesy of


2. US Fish and Wild Life Service


1 Comment

  1. December 24, 2008 at 10:56 am

    […] Vote Critically endangered silvery minnow – welcome back […]

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