7990

• UCREFRP Catalog Number: 7990
• Author: Tyus, H. M.
• Title: Razorback Sucker ‎(
• USFW Year: 1997.
• Copyright Material: NO

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Razorback suckers have been captured in breeding condition in many different habitats
and environmental conditions. Spawning has been documented in mainstream rivers, '
riverine-influenced areas of large impoundments, and wave-washed shorelines of
reservoirs. The ability to use a variety of habitats and flow conditions ma reflect
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adaptations to conditions in the historic Colorado River system. However, the absence
of any substantial level of recruitment makes it difficult to determine the habitat and flow
conditions that would be the most suitable for recovery efforts.. It is not known whether
all life history requirements can be met in either the mainstream river or an '
impoundment. For clarity, the following discussion of reproductive requirements and ,
habitat use is separated into lacustrine and riverine habitats.
Lacustrine habitats. The largest surviving stock of razorback suckers exists in
Lake Mohave in the lower Colorado River basin. Successful spawning has been
documented in Lake Mohave and numerous larvae have been collected Bozek et al.
(
1990, Marsh and Langhorst 1988). However, juveniles have been extremely rare in '
collections (Minckley et al. 1991). Spawning in Lake Mohave and other lower basin
reservoirs occurs eariy in the year, from January through April/May (Medal-Ulmer 1983,
Langhorst and Marsh 1986, Mueller 1989). Water temperatures during spawning '
ranged from 11.5-18°C (52.7-64.4°F) (Douglas 1952, Model-Ulmer 1983, Langhorst '
and Marsh 1.986). Spawning fish congregate and spawn in flat or gently sloping
shoreline areas over gravel, cobble, or mixed substrate types (Douglas 1952, Medal- '
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