7990

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

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Colorado River basin, the species never may have been common in whitewater
canyons there (Bestgen 1990).
Larvae and juveniles. Marsh and Langhorst (1988) observed that larval
razorback suckers in Lake Mohave remained near shore after hatching, but
disappeared within a few weeks. -Young hatchery-produced fish remain along
shorelines, in embayments along sandbars, or in tributary mouths, and later disperse
into the main channel or larger backwaters (Minckley et al. 1991). Paulin et al. (1989)
conducted a laboratory study that indicated 2-week old larval razorback suckers
actively, rather than passively, entered the drift and moved primarily at night. The
tendency to enter the drift suggests that the species takes advantage of downstream
transport for moving from spawning to nursery habitats, and may explain why existing
riverine spawning areas are upstream of presumed nursery areas in the Green River.
More than 2,000 drifting larvae have been captured from the mid and lower Green
River in afour--year period using a variety of sampling gear (R.T. Muth, personal comm.
1996).
Habitat needs of juvenile razorback suckers are not well known because juveniles are
not commonly encountered, especially in riverine habitats (Tyus 1987). Most
encounters involve just a few individuals, although R.R. Miller seined 6,600 larvae and
small juveniles along warm, shallow margins of the Colorado River at Cottonwood
Landing, Nevada in 1950 (Sigler and Miller 1963). Taba et al. (1965) collected a few
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