Lefebvre and Denson: Inshore spawning of Rachycentron canadum in South Carolina 
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Figure 2 
Histological micrographs of the ovarian phases of cobia (Rachycentron canadum) collected 
in South Carolina waters in 2007 and 2008. Scale bars = 200 pm. (A) Developing: primary 
oocytes (PO) dominate with few cortical alveolar (CA) present. Spawning capable: (B) late 
developing (subphase): vitellogenesis continues; multiple batches of vitellogenic oocytes (VO) 
are present; (C) actively spawning (subphase): hydrated oocytes (HO) show lipid coalescence; 
(D) past spawner 1 — recent spawning (subphase): most recent postovulatory follicles (POF) 
are 250 pm across longest axis; multiple batches of VO present; and (E) past spawner 2 
(subphase) — previous spawning: POF are less numerous and are smaller, more condensed, 
and triangular in shape; multiple batches of VO present. (F) Regressing: largest batch of 
VO are undergoing atresia (AO). 
for the first time in this spawning season. A single fe- 
male in the regressing phase was collected in offshore 
waters in early June 2008. Females with histological 
signs of previous spawning (visible POFs) were found 
in cobia collected inshore and offshore. All POFs were 
estimated to be greater than 12 hr old (Hunter and 
Macewicz, 1985; Roumillat and Brouwer, 2004), with 
the exception of one specimen collected during morning 
hours in May 2007, for which the POFs were estimated 
to be ~12 hr old. 
Two actively spawning females were collected from 
inshore waters in 2007. The first (121.6 cm FL and 27 
kg FW) was collected in mid-morning on 12 May in 
the Broad River (PRS). The second (93.4 cm FL and 11 
