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, 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 that 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.
- Determine Physical and Behavioral Conditioning Effects on Survival of Hatchery-Reared Bonytail and Razorback Suckers
- Development of a Native Fish Sanctuary System in the Colorado River Basin
- Interactions between Native and Non-native Aquatic Species in the Southwestern United States
- Investigations into the Early Life Histories of the Razorback Sucker and Bonytail in Cibola High Levee Pond, Arizona
- Native Fish Sanctuary Evaluation
- Wetland Flora, Fauna, and Water Quality Assessment at Topock Marsh
- A case for site acclimation in the reintroduction of the endangered razorback sucker (Xyrauchen texanus)
- A program for maintaining the razorback sucker in Lake Mohave
- A program to maintain the endangered razorback suckers in a highly modified riverine habitat
- Benefit of physical exercise on escape performance and preliminary testing of predator avoidance in razorback sucker (Xyrauchen texanus)
- Biological and water quality monitoring of native fish sanctuaries in the lower Colorado River Basin, 2005-2009
- Biological and water quality monitoring of native fish sanctuaries in the lower Colorado River Basin, 2006-2007
- Bonytail and Razorback Sucker in the Colorado River Basin
- Bringing back the bonytail and the razorback
- Bullfrog tadpole (Rana catesbeiana) and red swamp crayfish (Procambarus clarkii) predation on early life stages of endangered razorback sucker (Xyrauchen texanus)
- Cibola High Levee Pond Annual Report 2003
- Cibola High Levee Pond annual report 2004
- Cibola high levee pond: annual report for FY-2002
- Distribution, migratory behavior, and habitat use of razorback sucker (Xyrauchen texanus) in Lake Mohave, Arizona-Nevada
- Distribution, movements, and habitat use of razorback sucker (Xyrauchen texanus) in a lower Colorado River Reservoir, Arizona-Nevada
- Ecology of bonytail and razorback sucker and the role of off-channel habitats in their recovery
- Effectiveness of fish barriers and renovations for maintaining and enhancing populations of native southwestern fishes
- Factors influencing poststocking dispersal of razorback sucker
- Interagency Work Group attempts to save razorback sucker in Lake Mohave
- Lost, a desert river and its native fishes: a historical perspective of the lower Colorado River
- Movement patterns, behavior, and habitat use of razorback sucker stocked into the Green River at Canyonlands National Park, Utah
- Native fish sanctuaries of the Lower Colorado River: Cibola High Levee Pond Desert Pupfish Pond
- Observations of spawning razorback sucker (Xyrauchen texanus) utilizing riverine habitat in the Lower Colorado River, Arizona-Nevada
- Post-Stocking dispersal, Habitat Use, and Behavioral Acclimation of Juvenile Razorback Suckers (Xyrauchen texanus) in two Colorado River Reservoirs
- Predation by odonate nymphs on larval razorback suckers (Xyrauchen texanus) under laboratory conditions
- Predatory fish removal and native fish recovery in the Colorado River mainstem: what have we learned?
- Preliminary testing of the role of exercise and predator recognition for bonytail and razorback sucker
- Razorback sucker movements and habitat use in the San Juan River inflow, Lake Powell, Utah, 1995-1997
- Rescuing the razorback sucker
- Restoration of the razorback sucker in the Colorado River, southwestern United States
- Riverine science at the Fort Collins Science Center
- Small nonnative fishes as predators of larval razorback suckers
- Summary of fluvial sediment collected at selected sites on the Gunnison River in Colorado and the Green and Duchesne Rivers in Utah, water years 2005–2008
- Summary of research activities, 2006
- Survival of young razorback sucker in relation to stocking rates (fish/ha) and in the presence or absence of predator communities in Lake Mohave, Arizona-Nevada
- Techniques for monitoring Razorback Sucker in the Lower Colorado River, Hoover to Parker Dams, 2006-2007, Final Report
- Testing of golf course ponds at Page, Arizona for suitability as grow-out facility for razorback sucker using surplus fish from Ouray National Fish Hatchery
- The role of stocking in the reestablishment and augmentation of native fish in the lower Colorado River mainstem (1998-2002)
USGS Fort Collins Science Center
Denver Field Station
c/o Bureau of Reclamation
P.O. Box 25007 86-68220
Denver, CO 80225-0007