8071

• UCREFRP Catalog Number: 8071
• Author: Horn, M. J. and P. C. Marsh.
• Title: Production of Razorback Sucker in a Backwater at Yuma Cove, Lake Mohave, Arizona and Nevada, 1992.
• USFW Year: 1993.
• USFW - Doc Type: Tempe, Arizona.
• Copyright Material: NO

8

Growth in the Yuma Cove backwater substantially exceeded that

obtained for razorback suckers. under hatchery conditions (FWS

files, Dexter NFH), and was about twice that attained in central

Arizona urban lakes and elsewhere (Marsh 1990). This exceptional

growth may in part have been enhanced by a stochastic event. A

flash flood on 10 August discharged a visibly large quantity of

organic material, including abundant feral burrow (Equus asinus)

faeces, into the backwater (Burke and Horn, personal observations),

which undoubtedly contributed significantly to the nutrient budget

of the system. That influx of nutrients would have stimulated

primary productivity, which in turn enhanced secondary production

of zooplankters and benthic invertebrates. Thus, food resources

for young razorback suckers would have been enhanced, and could

have resulted in the observed growth rates.

At least five ripe males were among the group of fish removed from

the Yuma Cove backwater in November; sexually maturity thus had

been attained by nine months of age. Prior to this observation the

earliest age at maturation for males was two years, as reported for

some individuals at Dexter NFH and in central Arizona ponds (FWS

files, Marsh 1990, Minckley et al. 1991).