434 
Fishery Bulletin 95(3), 1 997 
were determined by using 
the least-significant-differ- 
ences multiple range test. 
Multiple regression analy- 
sis (Statgraphics Plus, 
Manugistics Corporation) 
was used to examine the 
relation between the ob- 
served protein growth rates 
and the following combina- 
tions of factors: the three 
experimental temperatures 
(20°C laboratory, 25°C labo- 
ratory, 25°C pond, 32°C 
pond), the three ration lev- 
els at 25°C (0, 5 prey/mL, 
and pond), RNA:DNA, and 
LDH activity. 
£ 
CO 
Results 
Growth rate versus 
prey density 
Standard length Starved 
red drum larvae (0 prey/ 
mL) kept at 25°C increased 
in standard length even as 
they were declining in dry 
mass (Figs. 1 and 2; Table 
1 ). The average size at death 
on day 6 was 2.89 mm, which 
corresponds to a daily in- 
crease of 0.075 mm/day for 
days 2-6. Surprisingly, these 
values were similar to those 
for larvae fed at 5.0 prey/mL 
at 25°C, which attained an 
average length of 2.90 mm 
by day 6. 
Growth in larvae fed ad 
libitum increased with in- 
creasing temperature in both the laboratory and 
ponds. At 20°C, day- 14 larvae averaged 4.13 mm, and 
very few of the larvae exhibited flexion of the noto- 
chord (Fig 1; Table 1). Laboratory-reared individu- 
als at 25°C grew to an average of 4.45 mm by day 14. 
Mean masses at day 14 were significantly different 
between the two temperatures (ANOVA: df= 1 , 
F=60.3, P<0.001). Flexion of the notochord within the 
tail region had begun by day 14 at 25°C, indicating 
the onset of transformation. Larvae raised in ponds 
at 25°C averaged 6.45 mm at day 14. Notochord flex- 
ion in these larvae began on day 9 or 10, when the 
12 15 
12 15 18 
Age (days) 
Figure 1 
Growth in standard length of red drum larvae raised in the laboratory and in growout 
ponds: (A) laboratory, 25°C and 0 prey/mL; (B) laboratory, 20°C and 5 prey/mL; (C) labo- 
ratory, 25°C and 5 prey/mL; (D) pond, 25°C; and (E) pond, 32°C. 
larvae were at a size between 4.11 and 4.50 mm. 
Pond-reared larvae at 32°C had reached an average 
standard length of 7.48 mm at day 14. Notochord 
flexion occurred on day 7 or 8, when larvae were at a 
length of 4.53 mm (similar to the size at flexion of the 
laboratory -raised larvae) and at an earlier chronologi- 
cal age than that of the laboratory-raised individuals. 
Mass measurements Growth in mass of laboratory- 
reared larvae at ration levels less than 5.0 prey/mL 
(0, 0.1, and 1.0 prey/mL) at 25°C was negative, and 
no larvae survived more than 8 days (Fig. 2). Slopes 
