408 
Fishery Bulletin 1 10(4) 
Table 4 
The number of cobia ( Rachycentron canadum) eggs (early-stage and late-stage) and larvae identified from plankton collections 
made in Port Royal Sound (PRS) and St. Helena Sound (SHS), South Carolina, in May and June 2008. Station codes: PA=PRS 
anchored net; SA=SHS anchored net; numbers correspond to a specific station. Station numbers with an asterisk were sub- 
sampled: numbers of eggs and larvae are estimated from the fraction sorted. No.=number of eggs or larvae; C= concentration 
(number/100 m 3 ). 
Date 
Station 
Early-stage eggs 
Late-stage eggs 
Larvae 
No. 
C 
No. 
C 
No. 
C 
6-May 
PA-5 
3 
0.61 
8-May 
SA-3 
1 
0.14 
14-May 
PA-8 
3 
1.66 
PA-9 
1 
0.55 
21-May 
SA-1* 
6 
0.93 
88 
13.58 
4 
0.62 
SA-2 
12 
4.6 
SA-3 
2 
0.28 
9 
1.27 
SA-6* 
4 
0.56 
12 
1.69 
28-May 
SA-1 
2 
0.38 
16 
3.08 
1 
0.19 
SA-3 
13 
2.64 
5 
1.01 
29-May 
PA-7 
10 
2.95 
1 
0.3 
PA-8 
15 
3.22 
PA-9 
3 
0.64 
PA-10 
1 
0.17 
1 
0.17 
3-Jun 
SA-1* 
24 
2.08 
12 
1.04 
4 
0.35 
SA-2* 
56 
7.06 
SA-3* 
496 
62.51 
64 
8.07 
4 
0.5 
SA-6* 
16 
2.02 
SA-7* 
4 
0.93 
4 
0.93 
5-Jun 
PA-7 
4 
0.57 
PA-8 
27 
3.18 
3 
0.35 
2 
0.24 
12-Jun 
PA-7 
15 
4.26 
PA-8 
5 
1.42 
2 
0.57 
PA-9 
7 
1.99 
PA 10 
1 
0.19 
18-Jun 
SA-3 
3 
0.54 
2 
0.36 
by recent genetic evidence that indicates the presence 
of distinct population segments along the southeastern 
coast of the United States (Darden 6 ). In a study of the 
genetic structure of cobia caught offshore from Florida 
to Virginia and from inshore locations in South Caro- 
lina and Virginia, Darden found that fish collected off- 
shore were a single population segment. Furthermore, 
the fish collected in inshore waters were genetically 
distinct from the offshore group and from cobia in other 
estuaries. If there is a distinct inshore South Carolina 
population segment, it could be maintained through 
spawning of cobia in their natal estuaries. 
The distribution of female cobia among the reproduc- 
tive phases may not represent the actual distribution 
in the population because the primary means of speci- 
6 Darden, T. L. 2009. Personal commun. South Carolina 
Dept. Natural Resources, Charleston, SC 29412. 
men collection was fishery dependent. In particular, 
the low percentages of females with developing and 
regressing ovaries and those females with histological 
signs of a recent spawn (POFs) are likely a result of 
fishery practices, particularly the seasonality of the 
recreational fishery. Cobia generally are thought to 
enter inshore waters when water temperatures reach 
20°C (Richards, 1967; Smith, 1996), and water tem- 
peratures in PRS and SHS reached 20°C before the 
end of April in 2008. Recreational anglers, in contrast, 
targeted cobia most heavily in May (Steele 4 ). Similarly, 
the fishing season for cobia may end before the fish 
leave inshore waters: the final plankton collections 
in PRS and SHS in mid-June contained cobia eggs 
and larvae, respectively, indicating spawning was still 
occurring in these areas despite a decrease in avail- 
ability of specimens from recreational anglers. Female 
cobia with ovaries containing POFs were underrep- 
