NANFA-- Lost, a Desert River and Its Native Fishes

Christopher Scharpf (
Fri, 11 Apr 2003 21:38:56 -0400

United States Department of the Interior
Denver Field Unit
P.O. Box 25007, D-8220
Denver, Colorado 80225-0007

April 11, 2003

We are pleased to announce the release of "Lost, a Desert River and Its
Native Fishes: A Historical Perspective of the Lower Colorado River." The
report can be accessed and downloaded at:
<>. The report
describes the dramatic changes that have occurred to the lower Colorado
River and its native fish communities. We are providing this to resource
managers, researchers, and the interested public so they might better
understand man's role in the disappearance of these unique fish.

Few people realize what the river was like. For instance, more than a
century ago Yuma was a thriving river port and large steam boats hauled
cargo from the Gulf of California upstream to ranches and mining
communities. Flows were typically shallow, turbid, warm, and quite
seasonal, being highlighted by destructive spring floods, flash floods in
the summer, and severe droughts.

River conditions changed as society introduced nonnative fishes and began to
harness the river's water. Today, the waters of the Colorado River serve
the needs of 22 million people in the United States and Mexico. Nearly
forty percent of the floodplain between the Grand Canyon and the
International Border is covered by storage reservoirs. Storage combined
with water diversion has completely dried up the lower river so that its
waters no longer reach the sea.

Native fish were used by Native Americans and were later commercially
harvested by Europeans. Non-native fishes were stocked as early as 1881 and
today more than 80 different species have been introduced. Many have formed
economically important sport fisheries but fish such as the largemouth bass,
sunfish, and catfish are also aggressive predators that displaced and preyed
upon native young. As a result, seven of the nine native fish are now
listed as federally endangered and the lower river has the dubious
distinction of being among the few major rivers of the world with an
entirely introduced fish fauna. Now managers are faced with the dilemma of
how to restore native communities.

We hope you find the information useful. A few hard copies are available
and can be obtained by contacting me at:


Gordon Mueller
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