WildEarth Guardians

A Force for Nature

Select Page

Current work in wildlife, rivers, public lands, and climate

Press Releases

Romantic, natural setting to breed silvery minnows

October 17, 2005
Sue Vorenberg The Albuquerque Tribune
In This Release

Monday, October 17, 2005
Romantic, natural setting to breed silvery minnows

Silvery Minnow Refugium is a simulated river to breed large amounts of fish and release them back into the river
Contact: Sue Vorenberg The Albuquerque Tribune

Dating is not a pleasant experience for the endangered Rio Grande silvery minnow.

There’s no wining and dining, no flowers and dancing.

Instead, the fish are knocked out, flooded with the fish hormone version of Viagra and bam – the next generation of fish eggs are laid before the unhappy couple even knows what happened.

So far, that’s the only way that the Silvery Minnow Refugium, attached to Albuquerque’s Biopark, can breed large enough fish populations to ensure survival of the species.

A $3 million facility that the broke ground on Tuesday could change that by giving the fish running river water, muddy overflowing banks and silt – quite the romantic setting, if you’re a fish.

Changes in the Rio Grande ecosystem from dams, development and other factors have hampered natural conditions in which silvery minnows breed, which has caused their numbers to decline, experts say.

The refugium, built in 2003, created a protected environment with a simulated river to breed large amounts of fish and release them back into the river. Efforts have been reasonably successful, allowing workers to release between 25,000 and 50,000 minnows back into the river each year.

But getting the fish to breed on their own is still difficult, said Holly Casman, aquarium manager at the Biopark.

“The tricky thing is nobody knows exactly what triggers the minnows to spawn in the wild, but they won’t breed consistently in captivity,” Casman said. “We think it might be associated with a big runoff event in the spring, like a thunderstorm or snowmelt. To get them to breed in a simulated environment, you have to try something similar.”

The new facility – called the Silvery Minnow Sanctuary – is aimed at creating a more natural setting for the fish to breed on their own.

It is a 1,200-foot channel that will be filled with Rio Grande water. Managers can adjust the flow and speed of the water and make the banks of the channel flood, said Ken Ferjancic, vice president of HDR-Fishpro in Santa Fe, which designed both the refugium and sanctuary.

“They’ll be exposed to all the natural conditions that they’d experience in the river – predation, variation in flows, so they get acclimated to river conditions,” Ferjancic said. “What that does is protect the genetic integrity of the fish. If they’re inside a building with no predators, they don’t develop a behavioral response to predation before they are released into the river.”

In the refugium, water flows in a circle, and managers can also regulate current speed and temperature, but it is netted and protected from the outside environment, Ferjancic said.

The refugium also doesn’t have floodable banks, which is where the fish probably bred historically, back when the Rio Grande used to flood the bosque regularly, Ferjancic said.

“In the spring months, we can double the flow in the sanctuary and create overbank areas where spawning, we hope, will occur naturally,” he said. “We could get literally millions of eggs in a spawn. That’s what we think happened historically in the river system.”

Getting the fish to breed naturally is less stressful on them and will save money for the silvery minnow preservation effort, Casman said.

“It’s hard on the fish, and there are only two or three trained people here that can get them to breed artificially,” Casman said. “It’s important to save them to protect diversity in the river. The minnow is sort of a canary in a coal mine. If they’re dying out, it says something about the overall health of the river itself. That’s why we’re trying to save them, and why these facilities are being built.”

A third facility, another type of refugium, is also in the works, possibly with even more enticing environments for the shy minnow.

It’s expected to be built in a few years when scientists learn more about the fish’s habits from the existing refugium and sanctuary, said Chris Gorbach, a hydraulic engineer with the Albuquerque office of the Bureau of Reclamation.

An Endangered Species Act ruling requires efforts to save the minnow, but each facility is spearheaded by a different agency.

The refugium was built by the Interstate Stream Commission and the city of Albuquerque. The Bureau of Reclamation is building the Sanctuary, and the third facility will probably also be built by the Interstate Stream Commission, Gorbach said.

“Different agencies are working on these, but we’re all talking to each other and working together to meet the challenges,” Gorbach said.


The Bureau of Reclamation is building a sanctuary where the Rio Grande silvery minnow can breed in captivity.

Cost: $3 million.

Size: A 1,200-foot channel of Rio Grande water with controllable flows and floodable banks.

Builder: Led by the Bureau of Reclamation, through funding secured by Sen. Pete Domenici, an Albuquerque Republican.

Dates: Started Oct. 11, expected to be finished next summer.

Source: Bureau of Reclamation

Copyright 2005 The Albuquerque Tribune – Reprinted with permission

Other Contact
There's no wining and dining, no flowers and dancing.