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Fishery Bulletin 96(2), 1 998 
in whole otoliths. For this reason, sagittal otoliths 
were subsequently removed from each fish, cleaned, 
dried, stored, and used to estimate the ages of fish. 
In order to determine whether it was necessary to 
section otoliths to reveal all translucent zones, the 
number of translucent zones in the otoliths of 100 
randomly selected <S. punctata, in which whole 
otoliths displayed at least one such zone, were 
counted prior to and after sectioning. Of the otoliths 
that showed two to six translucent zones after sec- 
tioning, 19% exhibited one less zone prior to section- 
ing. Furthermore, in those otoliths that displayed 
seven or more translucent zones after sectioning, over 
50% exhibited one less zone and 30% displayed be- 
tween two and four fewer zones prior to sectioning. 
Thus, the otoliths of S. punctata had to be sectioned 
in order to discern all the translucent zones in those 
structures, a procedure that is also required for age- 
ing several other fish species (e.g. Campana, 1984; 
Beamish and McFarlane, 1987; Casselman, 1987; 
Hyndes et al., 1992a). Otoliths were mounted and 
embedded in black epoxy resin and cut into approxi- 
mately 0.8-mm transverse sections with a diamond 
saw. Sections were mounted on glass slides and their 
surface ground on sequentially finer grades of 
carborundum paper , with particle sizes ranging be- 
tween ca. 30-10 pm. They were then coated with clear 
nail polish and examined microscopically under re- 
flected light. The distance between the outer edge of 
the outermost translucent zone and the periphery of 
each otolith (marginal increment) was measured. 
This was expressed either as a proportion of the dis- 
tance between the focus and the outer edge of the 
translucent zone, when only one translucent zone was 
present, or as a proportion of the distance between 
the outer edges of the two outermost translucent 
zones, when two or more translucent zones were 
present. Measurements were always made along the 
longest axis of each sectioned otolith and recorded to 
the nearest 0.05 mm. The number of translucent 
zones on each otolith was recorded. The birth date 
was designated as the midpoint of the main spawn- 
ing period, based on the trends shown by gonadal 
and oocyte development (see “Results” section). Von 
Bertalanffy growth curves were fitted to the indi- 
vidual lengths of females and males at the estimated 
age at capture by a nonlinear technique ( Gallucci and 
Quinn, 1979) with a nonlinear subroutine in SPSS 
(SPSS Inc., 1994). The von Bertalanffy equation is 
L,=L_[ l-e-™-'"], 
where L t = the length at age t (years); 
L rx = the mean of the asymptote predicted by 
the equation; 
K = the growth coefficient; and 
t 0 = the hypothetical age at which fish would 
have zero length if growth followed that 
predicted by the equation. 
The growth curves derived for females and males 
were compared by using a maximum-likelihood test 
(Kimura, 1980). 
A fine mesh seine net, which was 5.5 m long and 
consisted of 1-mm mesh, was used in alternate weeks 
between late July and late December 1994 to collect 
recently settled S. punctata from sheltered nearshore 
sites in regions similar to those sampled by the 21.5-m 
seine net. The standard length (SL) of each of these 
fish on each sampling occasion was measured to the 
nearest 0.1 mm, except when the sample size was 
large, in which case measurements were made on a 
subsample of 100 fish. 
Results 
Age and growth 
The mean marginal increment in sectioned otoliths 
with one translucent zone ranged from 0.42 to 0.54 
between May and October, but then fell precipitously 
to 0.09 in November, before gradually increasing to 0.39 
by April (Fig. 1). The marginal increments in otoliths 
with 2, 3, and 4-13 translucent zones also declined 
markedly between October and November and followed 
similar trends (Fig. 1). Thus, irrespective of the num- 
ber of translucent zones in the otoliths, the marginal 
increment declined markedly and then rose progres- 
sively only once during a 12-month period, demonstrat- 
ing that the translucent zones are formed annually. 
In order to determine the size and age composi- 
tion of S. punctata at different times of the year, the 
total lengths of fish caught in nearshore waters by 
seine net and in more offshore waters by anglers were 
pooled (Fig. 2A). Small S. punctata were first caught 
with seine nets in nearshore waters in early Novem- 
ber, in which month their lengths ranged from 25 to 
50 mm. By late December, the maximum length had 
increased to 68 mm (data not shown). The length 
range of the corresponding cohort, which comprised 
fish with otoliths that did not possess a translucent 
zone, increased to between 122 and 298 mm by Au- 
gust to October (Fig. 2A). Because the birth date of 
S. punctata was designated as 1 August (see below), 
the members of this cohort represent early 1+ fish. 
By November, a translucent zone had become dis- 
cernible at the edge of the otoliths of these 1+ fish. 
The length range of this cohort ranged from 158 to 
