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Texas scientists try to rescue drought-threatened fish

September 20, 2011 |  6:32 am

Brazos
Wildlife biologists have begun capturing thousands of minnows from Texas rivers parched by the state's worst drought in decades.

Over the weekend, scientists in Fort Worth collected smalleye and sharpnose shiners from the Brazos River — about 2,300 on Thursday and 800 on Friday, according to Kevin Mayes, an aquatic biologist with the Texas Parks and Wildlife Department.

Smalleye shiner

Texas biologists say such large fish rescues are rare, but they could become more common if the drought persists as meteorologists predict. As of this week, 86 species in Texas are considered endangered or threatened.

About 95% of the state is in the worst stage of drought, according to the latest U.S. Drought Monitor report, released Thursday. Texas just finished its driest 11 months on record and is in its worst single-year drought ever. The state also set a record for the hottest summer in the U.S., according to the National Weather Service.

The Brazos is the longest river in Texas, flowing from Curry County, N.M., about 840 miles to the Gulf of Mexico. It is the only place in the world where the shiners are found, Mayes said. Both species are waiting to be listed as threatened or endangered under the federal Endangered Species Act.

On Friday, scientists scooped dozens of fish out of river pools near Sagerton, about 150 miles west of Fort Worth, Mayes told The Times. They used a large net, then easily sifted out the 2-inch-long minnows, which are shinier than other fish in the river, he said.

On Monday, the rescued minnows were being held at the state's fish hatchery near Possum Kingdom Lake, about 90 miles west of Fort Worth.

“All of the fish are doing great,” Mayes said. “Every hatchery has risks, but we think that the risk is less than if we leave them out there in the wild.”

Water levels in the Upper Brazos have dwindled to isolated pools because of the drought, trapping minnows just when they need running water to reproduce, Mayes said.

“They’re small fish and they only live a couple of years. What has inspired us to get on the move is that [in] the Upper Brazos, a lot of the stream flow gauges have been reading zero for the last five months,” he said. “That directly overlaps the spawning season of these minnows.”

Scientists plan to release the minnows back into the Upper Brazos once water levels return to normal, he said.

They also plan to transplant more of the minnows from the Upper to the Middle and Lower Brazos downstream of Possum Kingdom Lake and Waco, Mayes said.

“If the rains don’t return and cause the river to start flowing again, these fish could go extinct,” Mayes said.

Meanwhile, a separate team rescued 110 federally threatened Arkansas River shiners and 60 peppered chubs from the Canadian River in the Texas Panhandle near the New Mexico border last week and took them to a federal fish hatchery in Oklahoma, he said.

Scientists are organizing rescue efforts for some mussels native to the state's rivers, Mayes said, some of which are listed as threatened under federal law. Officials may also try to collect West Texas desert fishes, he said.

"We pulled together a group of fish biologists to figure out what we need to do to make sure we don’t lose any Texas fishes," he said.

Several federally endangered species — including the fountain darter and the Texas blind salamander — may need rescuing if water levels drop in the Comal and San Marcos springs south of Austin.

Officials at the U.S. Fish and Wildlife Department’s National Fish Hatchery and Technology Center in San Marcos are maintaining captive populations of darters, blind salamanders and several other drought-sensitive species, but river levels had not dropped far enough to require rescues Monday, officials said.

“It’s not as crucial in San Marcos as it is in some of the other locations -- the springs are still flowing; they’re quite a bit below average, but it’s not critical,” said Tom Brandt, the center’s director.

It would not be unprecedented for the springs to stop flowing. Comal Springs ran dry in 1956, during the state’s epic seven-year drought, and stayed dry for six months, Brandt said. The fountain darter disappeared from the springs, which were restocked with darters from the San Marcos River in the 1970s, Mayes said.

During a drought in 2009, scientists saved plants from the springs such as Texas wild rice by moving them into deeper stretches of water, Brandt said.

“Most of what we’re doing is monitoring” now, he said, “watching what’s going on within the system.”

ALSO:

Texas wildfires largely controlled, but risks remain

Texas power company files suit against EPA

Interior Secretary Ken Salazar jabs GOP on San Joaquin River pact

--Molly Hennessy-Fiske reporting from Houston

Photo: (top) Scientists moved quickly this weekend to rescue two species of minnows indigenous to the state's longest river, the Brazos, where water levels had fallen dangerously low near Fort Worth because of the ongoing drought. Credit: Clint Robertson/Texas Parks and Wildlife Department.

Photo: (bottom) Smalleye shiner minnows need running water to breed in the Brazos. As a consequence low water levels, some minnows have become trapped in isolated pools, leading scientists to scoop up a bunch this weekend to hold in a nearby hatchery until river water levels rise. Credit: Clint Robertson/Texas Parks and Wildlife Department.

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