8142

• UCREFRP Catalog Number: 8142
• Author: Horn, M. J.
• Title: Nutritional Limitation of Recruitment in the Razorback Sucker ‎(
• USFW Year: 1996.
• Copyright Material: NO

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condition of larvae examined indicating effects are not uniform across the reservoir and

probably related to the variable effects of patchy resources and wind-generated currents.

Larvae from Yuma Cove, with the exception of a brief period of low condition, were

generally in as good or better condition than larvae raised on ad libitum rations in the

laboratory. Within Lake Mohave larvae persisted for up to 7 weeks following hatching,

though the average age was 15.3:t 7.3 days and 11.44:t 1.85 mm TL, smaller than

similar laboratory fish. All indices indicated although starvation is important, estimates

indicated between 23% and 78% larvae were starving depending on the year of collection

and the nutritional indice used, it alone cannot account for the apparently complete lack

of recruitment in this species. It is suggested that nutrition is instead acting in concert

with other limiting factors such as predation. Although larvae do starve, a greater

proportion exhibit reduced growth due to a less than optimal ration, keeping them within

the vulnerable size range for a greater length of time. Based on evidence of growth and

predation from other backwater studies, nutritional mortality at this time appears totally

compensatory. Regardless of whether larvae are starving or not they are all apparently

consumed by predators. If there were no predators there appears no reason why this

species should not persist.

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