Nevada Fish & Wildlife Office
Pacific Southwest Region

Razorback Sucker
(Xyrauchen texanus)

Razorback Sucker
Class: Actinopterygii
Order: Cypriniformes
Family: Catostomidae
Genus: Xyrauchen
Species: texanus
Length: over 3 feet and up to 13 lbs
Lifespan: 40 years or more
Feed: both plant and animal matter
Habitat: found only in the upper Green River in Utah, the lower Yampa River in Colorado and occasionally in the Colorado River near Grand Junction
 

Official Status:

Endangered
 

Life History:

Razorbacks are long lived; older fishes have been estimated at more than 40 years. Both males and females mature at age four. Spawning occurs in late winter or spring. Spawning takes place in a group settling to the bottom and releasing their gametes. The adhesive eggs become attached to the interstitial spaces in the gravel substrate. A single female is attended by 2 to 12 males, and the female will spawn repeatedly with several males. Hatching success depends on water temperature, with complete mortality at temperatures less than 50°F.

Razorback suckers inhabit a diversity of areas from mainstream channels to backwaters of medium and large streams or rivers. They prefer to live over sand, mud, or gravel bottoms. Razorbacks feed on algae, insect larvae, plankton, and detritus. The eyes are receptive to parts of the UV spectrum, particularly that portion of the retina that receives light from below. The razorback spends most of its life at depths where UV light cannot penetrate but they move into the shallows for breeding. In the shallows, males stake out a breeding territory and hover near the riverbed. When another male enters the breeding area, the defending male rolls his eyes downward to reveal the upper third of the eye generating a flash of reflected sunlight. The strongest reflected component of the flash lies in the UV spectrum. The intruding male, swimming overhead, can see the flash below and will shy away from it. The eye flashes are not visible from a distance underwater and can thus be used to signal intruding males without alerting predators. Females do not react to the eye flashes.
 

Distribution and Habitat:

  Found historically throughout the Colorado River Drainage, this fish has become very rare above the Grand Canyon. In Colorado, recent specimens have been taken only from the lower, mainstem Colorado, Gunnison, lower Yampa and Green rivers. The species is listed as an endangered species in Colorado and less than 70 specimens have been collected in the state since 1979.

This is a large river species not found in smaller tributaries and headwater streams. Found in water from 4-10 feet in depth, adults are associated with areas of strong current and backwaters. Many specimens taken in recent years are from off-stream impoundments and reservoirs. The razorback sucker eats both invertebrates and algae. Ripe adults have been observed in Colorado at several locations in late May and early June (Wick et al. 1981), although exact habitat requirements for succesful spawning are unknown.
 

Threats:

 

loss of large flood plain habitat and non-native fish predation

 

Actions / Current Information:

 

 
  • Federal Fish and Wildlife Permit Application form (Form 3-200-54)
     
  • Landowner Cooperative Agreement Template (Microsoft Word document)
     
  • Environmental Action Statement Screening Form for Programmatic Safe Harbor Agreement Benefitting Razorback Sucker and Bonytail Chub on Private Lands
     
  • Programmatic Safe Harbor Agreement for Voluntary Enhancement/Restoration Activities Benefitting Razorback Sucker and Bonytail within Clark County, Nevada
     
  • Landowner Certificate of Inclusion Template (Microsoft Word document)
     
  • Map: Potential razorback sucker and boytail rearing pond and refuge sites within Las Vegas Valley, Clark County, NV
        Federal Register Notice: Programmatic Safe Harbor Agreement for Nevada Department of Wildlife, Clark County, NV
    Last updated: April 16, 2014