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collected in Georgia confirms that formation of annual 
growth rings occurs during April and May (McDow- 
ell and Robillard, 2013). The formation of the opaque 
annual ring has been attributed to several factors, 
including seasonal temperature changes, feeding pat- 
terns, wet and dry seasons, and reproductive cycles 
(Beckman and Wilson, 1995). On the basis of our re- 
sults, formation of opaque rings in the GOM popula- 
tion appears to coincide with the peak of the spawn- 
ing season during April-May. 
Sciaenid life-history traits 
Despite the fact that a number of sciaenid species are 
commercially and recreationally important in the con- 
tinental United States, complete life-history informa- 
tion is available for only a small number of species. 
In particular, information on fecundity and spawning 
frequency is lacking for over half of the stocks listed 
in the Appendix. Such information about the reproduc- 
tive traits of these stocks is one important component 
for understanding population dynamics (Cortes, 1998), 
and priority should be placed on obtaining this infor- 
mation for these commercially or recreationally impor- 
tant stocks. 
All Sciaenidae exhibit some common life-history 
traits, such as indeterminate fecundity, batch spawn- 
ing, relatively small pelagic eggs, and an estuarine-de- 
pendent juvenile phase (Chao, 2002). However, we ana- 
lyzed the range for 5 reproductive and somatic traits 
with 2 principal component axes and explained 68.1% 
of the variation among species. This result is lower 
than the 91% total variation explained by Winemiller 
and Rose (1992) with analysis of 5 traits on 3 principal 
component axes for 147 fish species representing mul- 
tiple families, but variation in life history is reduced 
when analyzing traits of species within a single family. 
Waggy et al. (2006) examined the relationships among 
8 life-history variables in 11 sciaenid species occurring 
in the GOM and Caribbean and found that 2 principal 
components explained 86% of the variance, although 
several of the variables they included in their analy- 
sis were correlated. We have determined that the com- 
ponents of our analysis represent size-related aspects 
of life history (PC 1) and spawning season dynamics 
(PC 2), both of which combine somatic and reproduc- 
tive traits. Winemiller and Rose (1992) and Waggy et 
al. (2006) identified similar components in their life- 
history analyses. 
We identified 5 distinct sciaenid groups on the ba- 
sis of the PCA analysis (see Fig. 7), indicating these 
groups of species are very similar to each other. The 2 
largest sciaenids in the analysis, Red Drum and Black 
Drum from the GOM, compose group A and have simi- 
lar life-history traits, but they spawn at different times 
of the year (Murphy and Taylor, 1990; Nieland and 
Wilson, 1993). In group B, Sand Seatrout and South- 
ern Kingfish are both GOM species with similar sizes, 
spawning seasons, and spawning frequencies, but Sand 
Seatrout is a more pelagic species that spawns in the 
nearshore GOM (Shlossman and Chittenden, 1981), 
whereas Southern Kingfish tend to be benthic and es- 
tuarine spawners, on the basis of the common occur- 
rence of young fish in estuaries (Anderson et al., 2012). 
The Atlantic population of Southern Kingfish also is 
included in this group, indicating that geographic dif- 
ferences among a single species, although present, do 
not result in changes in basic life-history strategies. 
The inclusion of White Croaker of the Pacific in this 
same group indicates similar strategies across widely 
spaced regions. 
Group C consists of the species with the highest 
RBF, Spot and Silver Perch; both species occur in the 
GOM but have different spawning seasons and loca- 
tions (Cowan and Shaw, 1988; Grammer et ah, 2009) 
and therefore reduce potential competition among 
larvae. The GOM species Atlantic Croaker and Silver 
Seatrout are both in group D but have different spawn- 
ing seasons (White and Chittenden, 1977; DeVries and 
Chittenden, 1982), and the Atlantic population of At- 
lantic Croaker is found in this same group. Within 
group E, the Atlantic congeners Spotted Seatrout and 
Weakfish and the Pacific species Spotfin Croaker, and 
Yellowfin Croaker have similar spawning seasons and 
habitats within regions (Brown, 1981; Lowerre-Barbieri 
et al., 1996a; Miller et ah, 2009), indicating that life- 
history traits among this group are very similar. Geo- 
graphic differences in life-history parameters between 
Atlantic and GOM Spotted Seatrout (Brown, 1981; 
Murphy and Taylor, 1994; Brown-Peterson, 2003) ap- 
pear to be once again less important than overall life- 
history strategies. 
For all 3 of the sciaenid species that have both At- 
lantic and GOM populations — the Southern Kingfish, 
Atlantic Croaker, and Spotted Seatrout — those popula- 
tions are in the same groups as their conspecifics, but 
those 3 species are in 3 different life-history groups 
within the PCA. Therefore, the similarity of overall 
within-species life-history strategies appears to over- 
ride observed differences in reproductive seasons with 
latitude (Brown-Peterson and Thomas, 1988; Conover, 
1992). 
Overall, the PCA results indicate that groups A and 
E can be characterized as having a periodic or K life- 
history strategy but that group C has an opportunistic 
or r strategy (sensu Winemiller and Rose, 1992). Groups 
B and D (8 species) do not fit classic definitions of life- 
history strategies, indicating that strategies of smaller 
sciaenids with low fecundity may be more susceptible 
to environmental or physiological variation than larger 
sciaenids with high fecundity. Indeed, the importance 
of behavioral and physiological factors should be con- 
sidered when evaluating life-history variation (Rick- 
lefs and Wikelsik, 2002) because some observed vari- 
ations may be a result of physiological sensitivity or 
behavioral control mechanisms that are related to the 
environment. 
