7406

• UCREFRP Catalog Number: 7406
• Author: Bestgen, K. R.
• Title: Status Review of the Razorback Sucker,
• USFW Year: 1990.
• Copyright Material: NO

Razorback suckers are sometimes found in tributaries or off-
channel habitats prior to, or during, presumed spawning season
(McAda and Wydoski 1980, Tyus 1987, Osmundson and Kaeding 1989a,
Tyus and Karp in press). These off-channel habitats are often
warmer than the mainstream, especially in spring (Tyus and Karp in
press, Osmundson and Kaeding in review). The precise role of such
habitats in the life history of the razorback sucker is unknown
but may be related to feeding, resting,-egg maturation, spawning,
or other activities associated with reproduction.
Razorback suckers have never been directly observed spawning
in turbid river environment of the UCRB, but some data describing
presumed reproductive activity were obtained from capture of ripe
fish. In riverine habitats of the UCRB, the spawning season of
razorback suckers was generally later in the year and shorter in
duration than in Lake Mohave. Ripe razorback suckers were
generally collected from mid-April to mid-June (McAda and Wydoski
1980, Valdez et al. 1982a, Tyus 1987, Osmundson and Kaeding 1989a,
Tyus and Karp 1989, Tyus and Karp in press), but within any year
only over a 4-5 week period (Tyus and Karp in press). Similar to
Lake Mohave, spawning males outnumber spawning females by 2.5:1 in
the Green River. Similar male:female ratios (2.7:1 and 2.9:1 in
different years) have been observed for a closed spawning
population of white suckers (Quinn and Ross 1985). This was due,
however, to a higher incidence of non-annual spawning by females,
as the male:female sex ratio for the entire population was 1:1
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