188 
Fishery Bulletin 112(2-3) 
TabSe 4 
Seasonal spawning frequency for Southern Kingfish (Menticirrhus ameri- 
canus) in the northcentral Gulf of Mexico determined with 2 histological 
methods. The postovulatory follicle (POF) method is based on the pres- 
ence of POF <24 h and the oocyte maturation (OM) method is based on 
the presence of oocytes in OM. Only females in the spawning capable 
phase (including the actively spawning subphase) were used in this anal- 
ysis. Samples were collected from Mississippi Sound, Mississippi, between 
April 2008 and May 2009. 
Season 
n 
POF spawning 
frequency (days) 
OM spawning 
frequency (days) 
Early (April-May) 
79 
11.29 
11.29 
Mid (June-July) 
70 
3.50 
5.83 
Late (Aug.-Sept.) 
59 
19.67 
5.36 
Total (April-Sept.) 
208 
6.93 
6.93 
has a 6-month spawning period that occurs from spring 
to summer and that an individual female spawns, on 
average, 213.1 eggs g _1 OFBW once per week. Females 
reach sexual maturity at a relatively small size (171 
mm TL) and young age (1+ years). We report significant 
differences in sex-specific length at age and weight at 
length. Finally, we document how the life-history traits 
of this species are part of the multivariate continuum 
of sciaenid stocks in the coastal waters of the continen- 
tal United States. 
Our analysis of the reproductive traits of the South- 
ern Kingfish provided the timing of spawning through 
the use of both GSI and histological analysis, and we 
identified a single, extended spawning period. The 
spawning season for Southern Kingfish in the north- 
central GOM begins in late March and ends in Septem- 
ber, with peaks in male ( 1.56%) and female (4.75%) GSI 
values in April. Other investigators have previously re- 
ported similar spawning seasons for Southern Kingfish 
in both the Atlantic and GOM on the basis of macro- 
scopic inspection of the ovary and GSI values (Hildeb- 
rand and Cable, 1934; Bearden, 1963; Lagarde 2 ; Smith 
and Wenner, 1985; McDowell and Robillard, 2013). An 
extended spawning season (>3 months) is characteris- 
tic of most sciaenid species (Appendix). Our analysis 
of this reproductive trait places Southern Kingfish in 
group B (see Fig. 7), a group partially characterized by 
having the longest spawning season. 
Our finding of the existence of a single spawning 
season is in contrast to results from Harding and Chit- 
tenden (1987), who found on the basis of male and fe- 
male GSI and macroscopic classification of maturity 
that the spawning period in the northwestern GOM 
occurred from February or March to November and 
comprised 2 primary, discrete spawning periods (spring 
and fall). However, the Harding and Chittenden (1987) 
collections were from the deeper part of the bathymet- 
ric range of Southern Kingfish; more thorough collec- 
tions in estuaries, the surf zone, or the 
shallow inshore waters could resolve 
whether there are 2 discrete spawn- 
ing periods, as they have suggested, 
or 1 spawning period with 2 periods of 
recruitment. 
Although GSI values are typically 
good indicators of spawning prepared- 
ness, histological analysis can re- 
fine and more precisely delineate the 
spawning season and has not been 
previously performed for Southern 
Kingfish from the GOM. The spawning 
season estimated through our histolog- 
ical analysis matched our GSI results; 
spawning is initiated in April and ends 
in September. Additionally, there were 
fish in the spawning-capable phase in 
both March and October, although no 
females were in the actively spawning 
subphase during these months. Our 
estimate of the Southern Kingfish spawning period is 
supported by Anderson et al. (2012), who studied daily 
growth rings in otoliths from juveniles in the north- 
central GOM and estimated birth dates with back cal- 
culation. Although there were fish in that study with 
250 A 
7 0 7 7 S 7 2o 7 3 Sj 3 0 j 3 Sj ?o 7 <t S; 
7 s 0 *3% 3 °o 3s o "*°o *$0 s °o 
Oocyte size bins (pm) 
Figure 6 
Oocyte size frequency distribution for Southern King- 
fish (Menticirrhus americanus) collected from the Mis- 
sissippi Sound, Mississippi, between April 2008 and 
May 2009 and found to be in the (A) spawning-capable 
phase or (B) actively spawning subphase. 
