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The Mountain-Prairie Region


U.S. Fish and Wildlife Service
134 Union Boulevard
Lakewood, Colorado 80228

July 23, 1997

Contact: Connie Young (303) 236-2985, ext. 227

Fourth endangered fish uses Gunnison River "ladder"

Another Colorado squawfish swam up the Redlands Fish Ladder on the Gunnison River near Grand Junction, Colo., Wednesday (July 23) morning, the third endangered fish to use the 350-foot-long channel in the past two weeks and the fourth since the structure was completed last year.

The recent use of the ladder by squawfish probably is because river flows now are receding and water temperatures are rising, said Bob Burdick of the U.S. Fish and Wildlife Service in Grand Junction, Colo. Biologists say this is an encouraging sign about the ladder's potential success.

"It's noteworthy that we have seen three squawfish go through the ladder in the last 14 days," Burdick said. "Their movement may be related to spawning."

The fish found Wednesday was a 23-inch, 3 1/2-pound Colorado squawfish that had migrated to the ladder from more than 100 miles downstream, a discovery made possible because of a previously implanted electronic tag routinely used in endangered fish research. By waving an electronic bar code-like scanner under the belly of the fish, U.S. Fish and Wildlife Service researchers identified it as No. 1F41386206, which Utah fishery biologists had captured in 1995 in the Colorado River near Moab.

In addition to the four endangered fish, to date nearly 15,000 other native fish, such as flannelmouth suckers, bluehead suckers and roundtail chubs, have passed through the structure, reaching portions of the Gunnison River that had been off-limits for nearly a century. The man-made ladder has re-created a more naturally functioning river environment, despite the presence of the 12-foot-high concrete dam.

"The lower Colorado River Basin (downstream of Lake Powell) has been fragmented by dams and diversions that prevent fish from making their normal migrations, and many native fish have started to decline in number", Burdick said. "We want to prevent that from happening in the upper Basin before the numbers of fish get too low."

Before the ladder was built, when Gunnison River water reached the Redlands Diversion Dam, it all spilled over the top. Now, a flow of 25 cubic feet per second is diverted through the fish ladder. After entering at the bottom, fish swim up a series of steps to a "holding area" at the top. Biologists then sort and count the fish before releasing endangered and other native fish upstream.


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