Xyrauchen texanus

Taxonomy 
Scientific Name:Xyrauchen texanus
Common name:razorback sucker
Rank and Status   
Global Rank:G1 Native Status:Native
Subnational (State) Rank:S1 Endemic:No
US ESA Status:Listed endangered Sand Dunes:No
NNHP Tracking Status:At-Risk List Wetland:Yes
Other Agency Status Status Last Updated Status Comments
Bureau of Land Management - Nevada Sensitive BLM Nevada Sensitive Species List dated 2017-10-01
State of Nevada Protected Endangered Fish NAC 503.065.2
Nevada Wildlife Action Plan - 2012 Species of Conservation Priority
Nevada Wildlife Action Plan - 2005 Species of Conservation Priority
CCVI Score Increase Likely Conf. Low; Factors contributing to decrased vulnerability are dispersal/movement, physiological thermal niche, and genetic variation.
Distribution (NV Counties)

Status: Confident or certain

Clark
Summary Occurrence Data
Occurrence Count:10
Total Observed Area (hectares):Not Available
Maximum Known Elevation (m):Not available
Minimum Known Elevation (m):183
Links
Xyrauchen texanus data at NatureServe
Xyrauchen texanus photos and data at Encyclopedia of Life
Character Abstract
Identification Comments:
Subspecies Comments:
Food Habits:The razorback sucker is a planktivorous and benthic feeder, eating algae, planktonic crustaceans, and aquatic insect larvae. In Lake Mohave, Arizona-Nevada, diet of adults was dominated by planktonic crustaceans, diatoms, filamentous algae, and detritus (Marsh 1987).
Phenology Comments:
Reproduction Comments:
Migration Mobility:
Habitat Comments:The razorback sucker is found in the main stream of the Colorado River and large tributaries. Habitats include slow areas, backwaters, and eddies of medium to large rivers and their impoundments (3 of the 4 remaining populations of greater than 100 individuals are in reservoirs). This fish is often associated with sand, mud, and rock substrate in areas with sparse aquatic vegetation, where temperatures are moderate to warm (Sigler and Miller 1963). Limited data indicate that young tend to remain along shorelines, in embayments along sandbars, or in tributary mouths (see Minckley et al. 1991). In Lake Mohave, individuals were associated with inshore habitats except during the hotter months when they moved offshore possibly to avoid warmer water temperatures (Mueller et al. 2000). Spawning occurs most commonly near shore in streams over silty sand, gravel, or rock substrate at depths of up to about 6 meters (often in water less than 0.6 meter deep). Known and suspected spawning sites in the Green and other upper-basin rivers all are in broad, flat-water segments (Minckley et al. 1991). Ripe individuals often have been taken over or near coarse sand, or gravel or cobble bars, in flowing water. In reservoirs, spawning occurs on gravel bars swept clean by wave action, and also along shorelines over mixed substrates ranging from silt to cobble (USFWS 1994b). Spawning has been observed downstream from major impoundments, below Davis Dam and Hoover Dam (Mueller 1989). Larvae appear to remain in gravel until swim-up (USFWS 1990a). Apparently they prefer the shallow littoral zone for a few weeks after hatching, then disperse to deeper waters (USFWS 1994b). Seasonally inundated flood plains provide favorable feeding areas for young.
Ecology comments:In Lake Mead at least three sub-populations exist all associated with reservoir inflow areas. The Lake Mead population likely comprises less than 2,000 adult fish but this is the only wild population of the species known to show consistent and substantial successful natural recruitment. Reasons for this are not fully understood but might be associated with seasonal turbidity or other reservoir physical characteristics (Shattuck et al 2011). Recaptures and radio-tracking indicate that individuals may remain in one area (a few km long) for several months (USFWS 1990a), but individuals may move 100-200 km or or more over several years (Wick et al. 1982). In Lake Mohave, linear range lengths of 10 adults over 14 months were 18-72 km (mean 39 km) (Mueller et al. 2000). The razorback sucker usually swims in schools.
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