RAZORBACK SUCKER } Xyrauchen texanus
DESCRIPTION: Razorback suckers can reach 36 inches in length and weigh up to 140 pounds. Adult fish have a sharp-edged keel or "humpback." The fish’s back is olive to brown-black, its sides are brown or pinkish, and its belly is white to yellow.
HABITAT: The razorback sucker inhabits medium to large rivers and their impoundments and is usually associated with sand, mud, and rock substrate in areas with sparse aquatic vegetation, where temperatures are moderate to warm. It favors slow-moving water, backwaters, and eddies, and uses flooded lowlands and lower portions of tributary streams for resting and feeding during the breeding season.
RANGE: The razorback sucker formerly occurred throughout the Colorado River basin but is now restricted to less than a quarter of its former range. It is near extinction in the lower Colorado River basin. It occurs in the upper Colorado River basin in the lower Yampa River, Green River, mainstem Colorado River, and lower San Juan River.
MIGRATION: Historically, adult suckers moved up mainstem rivers and into major tributaries in spring. Currently, there seems to be one sucker population that is sedentary and another that moves extensively. Suckers may move considerable distances to spawn. In Lake Mohave, suckers move up to 30 kilometers between spawning areas and summer-use areas.
BREEDING: Suckers spawn primarily in near-shore environments, usually over gravel bars or rock substrate that is swept free of silt by currents. Several males will often accompany a single female during spawning.
LIFE CYCLE: Razorback suckers may live upward of 40 years.
FEEDING: Razorback suckers eat algae, planktonic crustaceans, aquatic insect larvae, plants, and detritus.
THREATS: The razorback sucker is threatened by alteration and fragmentation of habitat due to dams, altered river flow and degraded habitat from water diversion and hydroelectric projects, the introduction of nonnative fishes, livestock grazing, climate change, and pollution.
POPULATION TREND: The razorback sucker was once abundant throughout the Colorado River basin. It is near extinction in the in the lower Colorado River basin and extirpated from the Grand Canyon. In the lower basin, the only substantial population remaining is in Lake Mohave, and suckers are rare in all other areas, with small numbers in Lake Mead and Lake Havasu. There has not been significant natural recruitment of young fish to these populations for many decades. There are small numbers of suckers in the Green River, upper Colorado River, and San Juan River subbasins, as well as in small tributaries of the Gila River, such as the Verde River, Salt River, and Fossil Creek.