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Fishery Bulletin 95(4), 1 997 
ments form daily in larvae. However, daily growth 
increments have been validated in the otoliths of lar- 
val spot, Leiostomus xanthurus, a sciaenid relative 
of Atlantic croaker (Peters et al. 2 ), and we assumed, 
therefore, that increment deposition is daily in At- 
lantic croaker. Peters et al. 2 also demonstrated that 
the first daily increment forms in the sagittae of spot 
at the time of first feeding, which occurs in spot about 
5 d after hatching at 18 and 20°C (Powell and Chester, 
1985); thus, we added 5 days to our increment counts. 
Sagittal otoliths of Atlantic croaker begin to in- 
crease growth along their anterior and posterior axes 
during the late-larval stage, whereas lapilli main- 
tain concentric growth through the juvenile stage, 
potentially making lapilli preferable when using 
otoliths to backcalculate growth. In examining the 
potential for using lapillar counts as a surrogate to 
sagittal counts, we found under light microscopy that 
lapillar counts increasingly underestimated sagittal 
counts as fish increased in age. The microstructure 
in sagittal otoliths also had better defined incre- 
ments, leading us to assume that sagittal counts were 
more accurate predictors of age than lapillar counts. 
No differences in the size and age counts between left 
and right sagittal otoliths warranted the replacement 
of lost or damaged right otoliths with left otoliths. 
Size and distribution 
Offshore spawning and subsequent estuarine migra- 
tion of Atlantic croaker have been thoroughly docu- 
mented by studies with egg and larval size distribu- 
tions (Hildebrand and Cable, 1930; Wallace, 1940; 
Haven, 1957; Colton et al., 1979; Morse, 1980; Lewis 
Table 2 
Growth comparison between early- (July through August) 
and late-spawned (September through February) Atlantic 
croaker from 19.1 to 65 mm SL and from 51 to 142 d with 
an analysis of covariance (ANCOVA) of standard length 
(SL) of fish (mm), with age (d) as the covariate. Size ad- 
justed means equals the mean SL of fish, adjusted for the 
effects of age. 
ANCOVA 
A 
df 
F-value 
P-value 
Covariate age 
Main effect 
Early-spawned vs. 
1 
743.6 
P<0.001 
late-spawned 
Residual sums 
1 
89.9 
P<0.001 
of squares (d) 
r 2 
5,489.2 (211) 
0.78 
B Size adjusted means (mm) (SE) 
Early-spawned: 39.5 (0.6) Late-spawned: 32.3 (0.4) 
