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were mostly between days 20 and 30 (Fig. 2) at a mean TL of 10.1±0.2 <br />mm (P--25). surviving larvae fed at concentrations of 5, 10, and 50 <br />nauplii Lrl did not differ in mean TL at end of the experiment <br />(14.9±0.4 mm, 13.6±0.9 mm and 16.1±0.3 mm, W4, 7, and 28 <br />respectively). Fish fed 500 and 1000 nauplii were larger, 25.0±0.6 mm <br />(1=27) and 23.8±0.6 mm (127), but did not differ significantly in <br />size between one another (Table 5). <br />CoWlete yolk-sac absorption in razorback suckers, which was not <br />specifically identified in my experiments, is at about 8 d post- <br />hatching at 1500 (Minckley & Gustafson 1982). <br />Discussion <br />Greatest mortality of starved razorback sucker larvae in <br />Experiment 1 occurred between 20 and 30 d after hatching. Larvae from <br />other experiments, which received food either too late or in <br />insufficient quantity, also died in this time period. Larvae were <br />able to persist without food for as long as 11 d beyond yolk-sac <br />absorption with <30% mortality. A critical period (May 1974) for <br />these larval fishes, during which time they ttazst encounter appropriate <br />food or die, thus lies between yolk-sac absorption (-8 d), and 19 d <br />Post-hatching at 180C. Mortalities increased to >50% even thou food <br />was presented at 14 d, suggesting larvae had become too weakened to <br />feed. Mum, the point of irreversible starvation (Werner & Blaxter <br />1980, Powell & Chester 1985) was between 19 and 23 d after hatching. <br />16 <br />. ?I <br />1 <br />i:. <br />s'