468 
Fishery Bulletin 99(3) 
Table 2 
Summary of ANOVA and ANCOVA results for growth and foraging response variables of witch flounder larvae at different prey 
densities (no. of prey per liter). An ANOVA was used for orient frequency within the size range 10.5-20.8 mm; for all other response 
variables an ANCOVA was used. Age (weeks after hatching) was used as the covariate for growth response variables, whereas size 
(mm SL) was used for behavioral response variables. (* denotes a significant difference at a=0.05). 
MAP 
Source 
df 
F 
P 
Standard length (mm) 
Age 
1 
7041.4 
<0.001* 
Prey density 
2 
0.85 
>0.25 
Age x prey density 
2 
0.75 
>0.25 
Error 
66 
Dry weight (mg) 
Age 
1 
2640.4 
<0.001* 
Prey density 
2 
0.06 
>0.5 
Age x prey density 
2 
0.21 
>0.5 
Error 
18 
Body height (mm) 
Age 
1 
582.1 
<0.001* 
Prey density 
2 
0.03 
>0.5 
Age x prey density 
2 
0.28 
>0.5 
Error 
18 
Orientation frequency 
Prey density 
6 
4.71 
<0.01* 
Error 
42 
Fixate frequency 
Size 
1 
6.94 
<0.05* 
Prey density 
6 
1.29 
>0.25 
Size x prey density 
6 
0.52 
>0.5 
Error 
84 
Lunge frequency 
Size 
1 
15.8 
<0.001* 
Prey density 
6 
1.35 
>0.25 
Size x prey density 
6 
0.62 
>0.5 
Error 
84 
treatments (Table 2, Figs. 1 and 2). Larvae began 
to increase in body height around the mean size 
of 15 mm (Fig. 2B). The average absolute growth 
rate from week 0 to week 12 for all treatments was 
0.53 mm/d.. The average specific growth rate (SGR) 
from week 0-6 was 3.68%/d and from week 0-12 was 
2.61%/d. 
The survival results were not corrected for fish 
sampled lethally (20 per tank). The survival in all 
treatments was similar over the course of the experi- 
ment (Table 3) and was unaffected by prey density 
at week 12 (ANOVA; F 2 3 = 2.75, P=0.210). 
Experiment 2: Behavior 
Larval behavior was characterized by a shift from 
nondirected MAPs to locomotory activities between 
the mean sizes of 10.5-16.2 mm (Fig. 3, A and 
B). The increase in locomotory activities was due 
to an increase in the total time spent swimming 
(Fig. 3A). The average duration of a swim MAP 
increased from 3.2 to 86.3 seconds over the study, 
whereas the frequency of swimming decreased sig- 
nificantly (Table 4). A turn MAP was used during the 
early stage, disappearing by the time larvae reached 
