7277

• UCREFRP Catalog Number: 7277
• Author: Papoulias, D.
• Title: Survival and Growth of Larval Razorback Sucker,
• USFW Year: 1988.
• Copyright Material: NO

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energetic costs of searching for a dispersed food source may provide
an explanation for the differential growth.
At Dexter NFH, razorback suckers <12.0 mm TL positively selected
small organisms (rotifers and chironcmid larvae) 50.1 mm body width
and did not take larger potential foods. As larval fish grew, larger
Organisms (mainly cladocerans) were preferentially taken, until mean
size of animals ingested was 0.3 mm wide in fish of approximately 23.0
mm TL. Prey of appropriate sizes to be ingested were generally
abundant in the ponds. There was little preference for taxa that
could not be explained by size and abundance combined. Selection of
most organisms was random (as measured by Strauss' Li), and even where
positive or negative selection was indicated, it was scarcely
significant (except for cladocerans, which were positively selected by
larger fish; Fig. 10). Seifert (1972) reported a similar diet of
first rotifers and later cladocerans for larval white sucker, but
noted an overall indiscriminate feeding behavior. Wild larval
razorback suckers in Lake Mohave ate cladocerans most abundantly,
along with rotifers and copepods (Marsh and Langhorst 1988). Larvae
of the related cui ui (Chasmistes bus) 12.0 to 28.0 mm TL ate
cladocerans (32% by n umbers) , chirona mid larvae (26%) and copepods
(20%) in the Truckee River, Nevada (Scoppettone et al. 1986).
Maximum size of ingested prey was smaller than the maximm
possible sizes predicted from measurements of lip length. This trend
has been reported by others (Arthur 1976; Gadomski and Boehlert 1984),