378 
Fishery Bulletin 96(2), 1 998 
Tabie 2 
Number of reproductively active females of C. striatus sampled in “El Rincon” area based on histological staging for determina- 
tion of spawning frequency. POF = postovulatory follicles; Cl = confidence interval. 
Day of 
month 
(November) 
Hydrated 
oocytes 
POF day-0 
POF day-1 
POF day-2 
Total mature 
2 
1 
2 
2 
4 
23 
3 
3 
2 
2 
5 
28 
3 
1 
3 
4 
1 
13 
3 
5 
1 
0 
1 
13 
4 
0 
1 
8 
5 
27 
5 
4 
7 
1 
2 
22 
5 
1 
0 
0 
2 
17 
6 
2 
3 
4 
1 
17 
8 
1 
0 
2 
0 
12 
Total 
18 
19 
23 
21 
172 
% (average) 
11.71 
11.09 
13.44 
10.65 
95% Cl 
12 ±7 
11 ±7 
13 ±8 
11 ±4 
12% (±6), which yielded an estimation that spawn- 
ing occurred every 8 days. 
The range in batch fecundity for females caught 
in “El Rincon” was 50,000 to 450,000 hydrated oo- 
cytes for fish between 40 and 53 cm TL. The samples 
collected from the Uruguayan coast ranged from 
38,000 to 360,000 hydrated oocytes for females of 34 
to 52 cm. A test of equality of means for the batch 
fecundity values of both zones showed no significant 
difference (P>0.56). A test of equality of coefficients 
indicated that no significant difference existed be- 
tween the equations for BF vs. TL for the two areas 
(P>0.05). The general equations for the total length 
and total weight were determined by combining all 
data (Fig. 4, A and B). No statistical differences were 
observed between the mean values of relative fecun- 
dity obtained for both zones (P>0.25). This para- 
meter ranged between 50 and 420 hydrated oocytes 
per gram of female (ovary free); an increase in the 
number of oocytes with size was observed (Fig. 4, C 
and D). 
Discussion 
The results obtained indicate that striped weakfish 
is a multiple spawner with indeterminate annual 
fecundity. Hence, the potential annual fecundity is 
not fixed prior to the onset of spawning, and unyolked 
oocytes continue to mature and to be spawned dur- 
ing the reproductive season ( Hunter et al., 1992). This 
assumption is based on two lines of evidence: 1) the 
presence of maturing ovaries with postovulatory fol- 
licles (partially spent stage), which indicates that 
after spawning one batch of eggs, a new batch devel- 
ops and is released; and 2) oocyte size frequency, which 
shows a continuous distribution of growing vitello- 
genic oocytes. 
Reproductive activity of striped weakfish in the 
coastal waters of Buenos Aires province ranges from 
October to March, with a main peak in November 
(Cassia, 1986). The histological examination of ova- 
ries obtained during September did not show evi- 
dence of spawning, but those taken in early Novem- 
ber indicated considerable reproductive activity, with 
a high proportion of postovulatory follicles and the 
appearance of hydrated oocytes. This corroborates 
the hypothesis that the spawning of C. striatus in 
“El Rincon” area generally begins in October. Unfor- 
tunately, it was not possible to sample this species 
during the rest of the spawning season, which lasts 
about 6 mo. according to Cassia (1986). The long re- 
productive season of this species has also been ob- 
served in other sciaenids inhabiting temperate wa- 
ters, such as Seriphus politus (7 mo.) (De Martini 
and Fountain, 1981), Cynoscion nebulosus (7 mo.) 
( Brown-Peterson et al., 1988), Micropogonias 
undulatus (7 mo.) (White and Chittenden, 1977; 
Barbieri et al., 1994), Genyonemus lineatus (7 mo.) 
(Love et al., 1984), Cynoscion nothus (6 mo.) (De Vries 
and Chittenden, 1982) and Cynoscion regalis (5 mo.) 
(Merriner, 1976). In Argentinian coastal waters, the 
main sciaenid associated with C. striatus is the white 
croaker ( Micropogonias furnieri), which has repro- 
ductive activity from November to March (Macchi 
and Christiansen, 1996). 
