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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subsample~ hatching began about 6 d after fertilization and lasted 24 to 36 hr, after which

unhatched eggs were discarded.

Eggs spawned on March 9 hatched March 14 to 15, and about 150 larvae were

placed in each of3 tanks. Feeding 20 naupliHarva-I'3 times day-I (= 60 naupliHarva-l.

day.l) was commenced on March 26. Eggs collected on March 15 hatched March 21 to

22. Several hundred larvae (uncounted) were placed in each of 4 tanks, 2 fed Ad libitum

beginning March 29 by which time swim-up had occurred, and larvae in 2 tanks were

Starved. Larvae from the Suboptimal treatment were sampled March 26, April 2, AprilS,

and April 1 O. Those from Ad libitum and Starved treatments were sampled every second

day March 23 to April 14, or until no larvae remained. Sampling was prior ro first

feeding on each date; 10 to 20 larvae from each tank were caught haphazardly by fine-

mesh net and immediately frozen.

For processing, 4 to 5 larvae were thawed, each measured with dial calipers to the

nearest 0.1 mm total length (TL) and dissected under appropriate magnification (10 to 40

X, depending on larval size). Due to difficulties in locating otoliths by dissection, the

anterior part of each larva was removed and placed in 5% sodium hypochlorite (CloroxR);

all flesh was digested from otoliths in 1 to 2 min. For larger larvae, physical maceration

in the solution accelerated the process. Sagittae and lapilli were selected for study;

asterisci did not appear until - 2 weeks of age, and were therefore excluded from

consideration.

Otoliths were rinsed for about 10 seconds each in 1 % hydrochloric acid then dis-

tilled water to remove residual tissues, transferred to numbered slides, into immersion oil,