Facility offers natural
setting for breeding
Sue Vorenberg, Albuquerque Tribune
Monday, October 24, 2005
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ALBUQUERQUE -- 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 Bureau of Reclamation broke ground earlier
this month 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."
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