Rescuing the Razorback Sucker

Although it's been around for tens of thousands of years, Xyrauchen texanus, or the razorback sucker, is a fish few people recognize. Once abundant in the turbulent and unpredictable Colorado River, the razorback sucker is now restricted to a few remnant populations, the largest being found in Lake Mohave, Arizona-Nevada. Habitat loss due to channelization and reservoir construction, along with competition and predation by over 40 introduced fish species in the Basin, led to the listing of the razorback sucker as an endangered species in 1991.

Though several thousand, old relic razorback suckers spawn in Lake Mohave, few, if any of the young fish survive to reach adulthood. Eggs are often eaten by carp, and young fish become food for sunfish and other species. This has contributed to a 60% decline in the population (from 59,500 to 23,300) from 1988 to 1992. In an effort to restore and manage the razorback sucker population in Lake Mohave, a cooperative partnership called the Native Fish Work Group (NFWG) was formed. The NFWG is composed of biologists and resource managers from seven federal and state agencies including the Arizona Game and Fish Department, Arizona State University, Bureau of Reclamation, Biological Resources Discipline of the U.S. Geological Survey (formerly the National Biological Service), National Park Service, Nevada Division of Wildlife, and the U.S. Fish and Wildlife Service. Its main goal is to replace Lake Mohave's old razorback sucker population with young adults.

As a member of the NFWG, Gordon Mueller, a Research Fishery Biologist at the Fort Collins Science Center, has helped develop methods for capturing and rearing naturally-hatched razorback sucker larvae and juvenile fish. Larval and juvenile fish are captured during the spring spawning period using lights and dip nets. This year over 50,000, ½-inch, larval suckers were individually hand-netted by biologists and volunteers. Once captured, the young fish are fed and stocked in isolated "nursery" coves in Lake Mohave where predatory fish have been removed. The fish are allowed to grow to about 30 cm (12 in) in length and are then released into the reservoir. At that size, scientists believe the fish are large enough to escape predation and can potentially survive to live out the rest of their 50-year life span.

Over the next several years, the Native Fish Work Group plans to release a minimum of 10,000 young adult razorback suckers into Lake Mohave and monitor their survival.

Though the Lake Mohave program is not a long-term recovery solution, it is an appropriate conservation management program. It buys scientists time to investigate more permanent methods for recovering the fish by maintaining populations which also provide a source of fish for future stocking programs. Without aggressive management through stocking, the razorback sucker could easily succumb to extinction in the lower Colorado River Basin and a unique member of America's native fish community would be lost forever.

Special thanks goes to Bill Rinne from the Bureau of Reclamation, whose innovative leadership has fostered the development of this unique, endangered fish management program.

Razorback Sucker Facts:

  Grows to 75cm (2.5 ft) and 5kg (10 lb.)

 Lives up to 50 years

 Feeds on zooplankton and benthic invertebrates

 Used by Native Americans and early settlers as food and fertilizer

This work is part of the Colorado River / Native Fish Investigations: A Study of the Movements and Distribution of Adult and Juvenile Razorback Suckers in Lake Mohave. Arizona-Nevada.

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For more information, please contact:

Gordon Mueller

Also At FORT   Bibliography of Colorado Big Fishes