Brown-Peterson et al.: Meta-analysis of reproductive parameters of Lut/anus campechanus in the Gulf of Mexico 
47 
to define reproductively active females, which does not 
reflect the presence of a few individual females with 
high GSI values in each month. Therefore, the major¬ 
ity of the population was likely not reproductively ac¬ 
tive in April, September, and October, thus leading to 
a monthly mean GSI < 1.0. Furthermore, our spawning 
duration estimates cannot account for half months (i.e., 
for a decrease in GSI in the second half of a month), 
and may thus result in a slight underestimation of 
spawning season duration. However, we do estimate 
a 4.5-month duration of the spawning season since 
1994, which likely corresponds to a May through mid- 
September spawning season. An additional challenge 
in modeling spawning seasonality is the fact that GSI 
reflects proportion data, which can result in skewed 
model results. Finally, temperature is an important 
regulator of spawning seasonality, particularly at the 
beginning of the reproductive season (Brown-Peterson 
et al., 2002). Incorporation of a temperature compo¬ 
nent into future models of spawning seasonality may 
increase the robustness of the seasonal estimates. An 
understanding of the duration of the spawning season, 
as well as how it may vary across time and with age is 
important for the most accurate determinations of age 
and size at sexual maturity, spawning frequency, and 
annual fecundity, which are all important metrics for 
optimal management of red snapper stocks. 
The estimated decline in red snapper reproductive 
parameters from 1991 through 2017 may raise concern 
for the continued recovery of the red snapper popula¬ 
tion, particularly in the northwestern GOM. However 
our results are primarily based upon reproductive 
samples from young females (< age 6), similar to those 
from other studies (Porch et al., 2015; Glenn et al.; 
2017, Karnauskas et al.; 2017; Kulaw et al., 2017). Ku- 
law et al. (2017) suggest that reductions in reproduc¬ 
tive output of young females may be more than offset 
by increasing contributions from older females. Unfor¬ 
tunately, older age females (e.g. > age 9) are uncom¬ 
mon among reproductive studies despite estimates that 
show that peak per-capita reproductive output occurs 
around age 14 (Porch, 2007; Porch et al., 2015; Ku¬ 
law et al., 2017). Owing to the economic importance of 
GOM red snapper, we expect sampling for reproductive 
metrics to continue and possibly increase over time. Al¬ 
though slow to accrue, reproductive data are being col¬ 
lected from older females. The increasing abundance 
of older red snapper, particularly in the northwestern 
GOM (Porch et al., 2015, Karanauskas et al., 2017, 
Table 2.24 in SEDAR 52, 2018), suggests a changing 
population structure that has likely been aided by 
management regulations to reduce fishing pressure. 
Ultimately we do want to account for age-based effects 
of reproductive compensation and recommend modeling 
the sensitivity of compensation in predictions of stock 
status as discussed by Rose et al. (2001). Density-de¬ 
pendent reproductive compensation, if it exists, has im¬ 
portant management implications because reproductive 
productivity is the basis for stock assessment projec¬ 
tions and reference points (Rose et al., 2001, Porch et 
al., 2015). Continued monitoring and analysis of repro¬ 
ductive attributes over the long term, such as those 
presented here, will provide insights into red snapper 
biology and stock condition. 
Acknowledgments 
We thank D. Kulaw, H. Glenn, C. Downey and G. 
Stuntz for sharing raw data. Staff from the National 
Marine Fisheries Service (NMFS) Southeast Fisheries 
Science Center, T. Moncrief, and M. Oshima assisted 
with collection and analyses of NMFS and Mississippi 
data. X. Zhang and A. Chester made helpful comments 
on the manuscript. Analyses were performed on the 
Texas Advanced Computing Center Lonestar 5 super¬ 
computer. Funding from the National Fish and Wild¬ 
life Federation in collaboration with the Mississippi 
Department of Environmental Quality, Covington Civil 
and Environmental Engineering and the Mississippi 
Department of Marine Resources (NBP) and the Office 
of Graduate Studies at the University of Texas-Austin 
(CRP) supported the authors. 
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