Craig et al.: Population biology and harvest of Acanthurus lineatus 
685 
the outer reef flat (Fig. 6). The settlement pulse oc- 
curred one month earlier at Matu’u as indicated by 
the significant site-time interaction detected by the 
repeated-measures MANOVA (P=0.03, F=4.67, nu- 
merator df=22, denominator df=6). In previous years, 
similar large pulses occurred in earlier months (Nov- 
Mar; senior author, pers. obs.). 
Seasonal changes in fish condition 
Fish condition factor (CF) peaked in summer and 
declined rapidly thereafter (Fig. 7). For mature fish, 
a decline in CF after the spawning season was ex- 
pected, but a similar decline was evident among im- 
mature fish. Postabdominal fat bodies also declined 
Jun Aug Oct Dec Feb Apr 
Figure 5 
Monthly gonadosomatic index (GSI) for mature males and females, and im- 
mature A. lineatus, 1991-94 combined. Also shown are months when spawn- 
ing was directly observed at Afao (stars). 
Table 1 
Correlation coefficients between monthly averages for physical and biological variables: gonadosomatic index (GSI), condition 
factor (CF), and paired fat bodies of A. lineatus. P = probability value. 
Water 
temperature 
Daylength 
Calm surf 
index 
Rainfall 
Feeding 
hours 
GSI: mature fish 
0.034 
0.906 
0.418 
0.36 
0.817 
P>0.1 
P<0.001 
P>0.1 
P>0.1 
P<0.01 
GSI: immature fish 
0.347 
0.129 
0.252 
0.335 
0.311 
P>0.1 
P>0.1 
P>0.1 
P>0.1 
P>0.1 
CF: mature fish 
0.495 
0.703 
0.65 
0.667 
0.511 
P>0.1 
P<0.02 
P<0.05 
P<0.02 
P<0.1 
CF: immature fish 
0.846 
0.546 
0.925 
0.706 
0.343 
P<0.001 
P<0.1 
P<0.001 
P<0.02 
P>0.1 
Fat bodies: mature fish 
0.77 
0.228 
0.702 
0.491 
0.036 
P<0.01 
P>0.1 
P<0.02 
P>0.1 
P>0.1 
