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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Larvae obviously must encounter food of adequate quality and in
sufficient quantities within a relatively short period of time if they
are to survive. Threshold prey density, beyond which survival
differences were not significant, was 50 nauplii 171. The minimum
prey density resulting in <50% mortality was between 10 and 50 nauplii
L l.. At 50 nauplii L 1, larvae were receiving 50 to 60 nauplii d71
each, at both beginning and end of the experiment. In treatments
where jars received 5 and 10 nauplii L`1, larval mortalities during
the experiment resulted in a range of 30 to 60 nauplii fish-1 d71 at
termination. These surviving fish grew as large as those in jars
receiving -50 nauplii 1;-1 d71 from the outset (treatment = 50 nauplii
L 1), which may indicate that 30 to 60 nauplii fish-1 d-1 is a minimum
necessary for survival during the critical period.
Larval fish utilize energy from foods directly for growth
(Blaxter 1969). Rapid growth makes them less vulnerable to predation
(Cushing 1976), but perhaps more dependent on reliable exogenous food
supplies due to a lack of energy reserves (O'Connell & Raymond 1970,
Taylor & Freeberg 1984). Larvae that had been starved for different
periods, but survived to take advantage of food when finally offered,
grew reasonably well compared to larvae fed from d 1 of the
experiment. Those surviving starvation for 31 d, then fed for the
remaining 19 d, achieved an average TL of 15.8 mm (I-2), while those
offered abundant food during the entire experimental period of 50 d
grew to 23.2±0.5 mm (W24). The same trend was seen for larvae
receiving different amounts of food. Jars receiving 5 nauplii I ;-l