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Fishery Bulletin 1 10(4) 
for cobia has increased over the past decade (Steele 4 ). 
Cobia continues to gain socioeconomic importance as a 
game fish throughout much of its range, supporting an 
expanding charterboat industry; however, the current 
status of this stock is unknown along the southeastern 
United States. 
In spring and early summer, cobia in the western 
North Atlantic are thought to migrate along with 
warming waters from Florida to as far north as the 
mid-Atlantic Bight (Shaffer and Nakamura, 1989). Dur- 
ing this presumed northward migration, cobia enter 
high-salinity bays and estuaries, including Port Royal 
Sound (PRS) and St. Helena Sound (SHS) in South 
Carolina, Pamlico Sound in North Carolina (Smith, 
1996), and Chesapeake Bay (Shaffer and Nakamura, 
1989), where they are readily available to inshore recre- 
ational anglers. Reasons for the inshore movement are 
not fully understood, but it is hypothesized that they 
may be following prey or aggregating to spawn. 
On the east coast of the United States, the spawning 
season for cobia extends from April to September (Lotz 
et ah, 1996; Smith, 1996; Burns et al. 1 ; Brown-Peterson 
et al., 2001); the cobia is an indeterminate batch spawn- 
er with group-synchronous oocyte development and is 
capable of spawning multiple times during a season 
(Biesiot et al., 1994; Lotz et al., 1996; Brown-Peterson 
et al., 2001; van der Velde et al., 2010). Regional peaks 
in spawning, as designated by maxima in the gonad- 
osomatic index (GSI), correlate with the migration of 
cobia from Florida northward. Spawning peaks along 
the Atlantic coast of the southeastern United States 
in May (Shaffer and Nakamura, 1989; Burns et al. 1 ), 
off the coast of North Carolina in June (Smith, 1996), 
and in Chesapeake Bay in June and July (Joseph et al., 
1964). In South Carolina, maximal spawning activity 
of cobia in May corresponds to peak fishing effort, as 
evidenced by increased landings during this month 
(Steele 4 ). During the spring recreational fishery for 
cobia in South Carolina, cobia are easily accessible 
to anglers in the major coastal sounds, as they are in 
other states where they enter inland waters. Because 
the inshore migrations of this fish into PRS and SHS 
correspond with its spawning season, it is probable that 
these estuaries serve as spawning habitat. 
Beyond a knowledge of spawning season, a paucity 
of information exists on spawning habitat and daily 
spawning periodicity of wild cobia, because much of the 
previous research on this species has focused on age 
and growth (Smith, 1996; Franks et al., 1999), feeding 
habits (Smith, 1996; Arendt et al., 2001), and general 
reproductive biology (Biesiot et al., 1994; Lotz et al., 
1996; Smith 1996; Brown-Peterson et al. 2001; van der 
Velde et al. 2010). Hassler and Rainville (1975) collected 
eggs in the Gulf Stream off North Carolina and sug- 
gested that spawning took place offshore. Burns et al. 1 
also proposed offshore spawning because of a scarcity 
of fish with histological signs of final oocyte maturation 
4 Steele, G. 2009. Personal commun. South Carolina 
Department of Natural Resources, Charleston, SC 29412. 
(FOM) collected in nearshore waters of the Gulf of Mex- 
ico and the Atlantic coast of the southeastern United 
States. It has been proposed that inshore spawning of 
cobia occurs in the lower Chesapeake Bay on the basis 
of egg collections immediately south of this bay (Joseph 
et al., 1964) and the ovarian condition of females col- 
lected in this bay (Richards, 1967). In North Carolina, 
Smith (1996) suggested that cobia spawned adjacent 
to inlets, on the basis of the presence of eggs in neus- 
ton net collections within inlets and a lack of females 
caught inshore that were undergoing FOM. Addition- 
ally, Ditty and Shaw (1992) reported eggs and larvae 
from another high-salinity bay, Crystal Bay, Florida. 
Our objective was to determine whether cobia spawn 
within 2 high-salinity estuaries in South Carolina, PRS 
and SHS. Histological analysis of ovarian tissue col- 
lected in 2007 and 2008 was used to evaluate the repro- 
ductive status of female cobia caught in the recreational 
fishery both inshore and offshore of these estuaries. A 
study of egg development conducted in 2007 and 2008 
with hatchery-reared cobia eggs provided embryological 
development characteristics and insight on time of day 
of spawning for wild cobia. An ichthyoplankton survey 
targeting cobia eggs and larvae in PRS and SHS was 
conducted during the 2008 spawning season to provide 
additional evidence of spawning locations. We discuss 
the results of this project, particularly with respect to 
the occurrence of springtime inshore aggregations of 
cobia, in light of the increasing fishing pressure cobia 
are experiencing and in regard to current management 
regulations. 
Materials and methods 
Fish collections and reproductive biology 
Fresh and frozen cobia specimens from PRS and SHS, 
South Carolina (Fig. 1), were collected by members of the 
Estuarine Finfish Research Group at the South Carolina 
Department of Natural Resources (SCDNR) at fishing 
tournaments and from cooperating anglers, recreational 
fishing guides, and employees of the SCDNR during 
the period from April to June in both 2007 and 2008. 
Specimens were measured for total length (TL, milli- 
meters) and fork length (FL, millimeters) and weighed 
(fish weight [FW]) to the nearest kilogram. Sex was 
determined macroscopically, and gonads were excised, 
stored on ice, and transported to the SCDNR Marine 
Resources Research Institute (MRRI; Charleston, SC). 
Date, time, and location of capture were noted when 
available: fish collected within PRS and SHS were des- 
ignated as “inshore” specimens, and those fish collected 
in the ocean beyond the barrier islands were designated 
as “offshore” specimens. Some cobia carcasses were accu- 
mulated in freezers located at marinas and tackle stores: 
anglers donated the carcasses after filleting, and the 
aforementioned information was voluntarily recorded. 
At the MRRI, gonads were weighed to the nearest 
gram, and the GSI was calculated: 
