Clardy et ai Life history of Menticirrhus americanus and other sciaenids 
191 
Unfortunately, spawning-frequency data are avail- 
able for only 11 of the 24 economically important sci- 
aenid species or populations and, for that reason, were 
not included in the PCA of reproductive and somatic 
traits. Therefore, the importance of spawning frequency 
to the reproductive and somatic relationships between 
Southern Kingfish and other sciaenids is unknown. 
The OM method appeared to be a reliable indica- 
tor of spawning frequency of Southern Kingfish in the 
GOM. Similarly, McDowell and Robillard (2013) used 
the OM method (specifically, presence of hydrated oo- 
cytes) to determine spawning frequency of Southern 
Kingfish from the SAB, although they did not pres- 
ent seasonal differences in spawning frequency. In our 
study, the OM method indicated that no significant 
difference existed between seasons as was observed 
with the POF method. The interspawning interval at 
the end of the season was longer when calculated by 
the POF method than when estimated with the OM 
method — a result that was likely due to a sampling 
bias. Fish that had finished spawning for the year may 
have moved out of the sample areas, whereas females 
that were still preparing to spawn remained in those 
areas. Therefore, fish that contained oocytes in the OM 
stage may have been more vulnerable to capture than 
fish with POFs. Similar differences in spawning fre- 
quency between methods were noted in the late sea- 
son of Silver Perch (Grammer et ah, 2009), where the 
OM method revealed an estimated 1.6 days between 
spawnings and the POF method indicated an estimated 
16 days between spawnings. Although Grammer et al. 
(2009) stated their results may have been a function of 
low sample size (n=16), our study had a larger sample 
size (n- 59) that should not have been a contributing 
factor to the large difference observed. Interestingly, 
on the basis of percentage of spawning fish captured 
(OM method), spawning frequency of Southern King- 
fish from Georgia also was highest at the beginning of 
the reproductive season (March and April; McDowell 
and Robillard, 2013). 
Female Southern Kingfish in the northcentral GOM 
reached sexual maturity as small as 163 mm TL, cor- 
responding to 1 year of age. Females reached 50% ma- 
turity by 171 mm TL and 100% maturity by 211 mm 
TL, both at age 1. These results are consistent with 
reports from Smith and Wenner (1985), who estimated 
that females from the SAB reached TL§q at 192 mm TL 
at age 1 and TL\qq at 230 mm TL, also at age 1. Re- 
cently, McDowell and Robillard (2013) have confirmed 
these estimates of TL 50 (199 111 m TL) and 50% maturi- 
ty ( 1.1 years), indicating little change in the population 
of Southern Kingfish from the SAB over the past 25 
years. Similarly, Haluch et al. (2011) reported female 
TL 50 at 167 mm TL from the area of Santa Catarina, 
Brazil, with TL\qq at 228 mm TL. In contrast, Militelli 
et al. (2013) found TL 50 for females in the coastal zone 
of Buenos Aires, Argentina, to be 223 mm TL, although 
this result was based on a relatively small sample size 
(n=54). Harding and Chittenden (1987) noted TL 100 at 
250 mm TL (with few maturing, virgin fish past 220 
mm TL) for fish in the northwestern GOM, providing 
further evidence that Southern Kingfish in the GOM 
reach sexual maturity by age 1. Many sciaenids have 
developed a strategy to mature in the first year of life 
(Waggy et ah, 2006; see Appendix); 10 of the 17 species 
or populations analyzed in the PCA were in the low 
age-at-maturity quadrats of the plot (groups B, C, and 
D in Fig. 7). 
Population-level characteristics, such as mortal- 
ity rates and longevity, have been shown to correlate 
with individual growth parameters (Beverton and Holt, 
1959; Lorenzen, 2005). Therefore, the somatic growth 
characteristics of Southern Kingfish discussed here 
provide a proxy for the determination of these char- 
acteristics that can aid in the management of the spe- 
cies. Our results indicate geographic differences in the 
maximum length and age of Southern Kingfish, as well 
as sex-specific differences in growth and condition. 
The maximum length from our study (348 mm TL) 
is similar to the lengths reported by Bearden (1963) on 
the East Coast of the United States (338 mm TL) and 
by Harding and Chittenden (1987) for the northwest- 
ern GOM (345 mm TL), but this result is smaller than 
the maximum size of 404 mm TL (Smith and Wenner, 
1985) and 419 mm TL (McDowell and Robillard, 2013) 
reported for fish off the Atlantic coast of the southeast- 
ern United States. In our study, males from the GOM 
were found to have a smaller mean size (211.2 mm TL) 
than that of females (238.5 mm TL). Sex-specific differ- 
ences in maximum length also were reported by Hard- 
ing and Chittenden (1987) and McDowell and Robillard 
(2013) for Southern Kingfish, and such differences are 
common for species in this family (Chao, 1995, 2002). 
On the basis of annuli counts in sagittal otoliths, 
maximum age for both males and females in the north- 
central GOM was 4+ years. The oldest reported South- 
ern Kingfish was an individual that reached age 6 from 
the Atlantic coast of the southeastern United States 
(Smith and Wenner, 1985), although this age determi- 
nation was made with scale annuli, which is less accu- 
rate than age determination from otoliths (VanderKooy, 
2009). Recent aging of Southern Kingfish from Georgia 
with the use of otoliths revealed a maximum age of 5 
years, with the majority of fish <age 3. The maximum 
age and sizes of Southern Kingfish estimated in this 
study provide additional evidence that this species is of 
a relatively small size and has a short life span. Many 
other sciaenids are typically relatively small and have 
a short life span (Waggy et ah, 2006; see Appendix); 10 
of the 17 stocks analyzed in the PCA were in the small 
maximum TL quadrants of the plot (groups B, C, and 
D in Fig. 7). 
Annual ring formation in otoliths of Southern King- 
fish occurred from April to May, a finding that differs 
from the reported marginal increments in scales by 
Smith and Wenner (1985), who found that the scale 
annulus was formed in the winter and early spring. 
However, analysis of otoliths from Southern Kingfish 
