44 
Fishery Bulletin 117(1-2) 
Year 
Figure 4 
Estimated red snapper (Lutjanus campechanus ) spawning interval from 1991 through 2002 and 2009 through 2017 in 
the northern Gulf of Mexico (GOM), calculated on the basis of evidence of oocyte maturation (OM, panels A, B, C) and 
postovulatory follicles (POFs, panels D, E, F). Spawning interval estimates for each study each year are indicated by 
black (northeastern GOM) or green (northwestern GOM) points with 50% (thick line) and 95% (thin line) credible in¬ 
tervals. Time series were estimated for combined regions (panels A, D) or separately in the northeast (panels B, E) and 
northwest (panels C, F). The horizontal solid line in each panel indicates the annual time series trend and the dashed 
lines show the 50% and 95% credible intervals. Extreme credible interval values are indicated by arrows. Note the dif¬ 
ference in scale of the Y axis in graph B. The inset in graph A clarifies spawning interval estimates from 1999 through 
2001 because of the large number of studies during those years. The insets in graphs D and E are study level spawning 
interval values that exceed the y-axis scale. 
35.7 (29.1-43.1) eggs/g ovary-free body weight in 2017 
(Fig. 5A). When regions were considered separately, 
RBF showed more modest changes in the northeast¬ 
ern region where estimated values changed from 70.7 
(58.8-84.1) eggs/g ovary-free body weight in 1991 to 
85.3 (75.0-97.4) eggs/g ovary-free body weight in 2000 
and then decreased to 51.4 (41.1-62.9) eggs/g ovary- 
free body weight in 2017 (Fig. 5B). In contrast, RBF 
varied substantially in the northwestern region, shift¬ 
ing from 33.6 (21.3-50.0) eggs/g ovary-free body weight 
in 1994 to a high of 84.7 (68.2-103.3) eggs/g ovary-free 
body weight body weight in 2001 and then decreasing 
to 32.0 (25.8-39.2) eggs/g ovary-free body weight in 
2015 (Fig. 50. Because data from the northwestern 
GOM were available only between 1994 and 2015, an¬ 
nual estimates cover a smaller range. 
Discussion 
As a result of management-based recovery, red snapper 
abundance in the GOM has increased rapidly in recent 
years (Cass-Calay et al., 2015, SEDAR 52, 2018). Given 
this increasing abundance, and in particular the likeli¬ 
hood of the age structure of the stock becoming less 
truncated, Porch et al. (2015) and Kulaw et al. (2017) 
commented on the need to monitor red snapper repro¬ 
ductive traits over time. Regarding reproduction, two 
competing conditions may occur as a stock rebuilds. 
The first condition is an increase in abundance of older 
ages, which may lead to increased population-level egg 
production because red snapper reproductive metrics 
(e.g., batch fecundity, spawning frequency, and spawn¬ 
ing season duration) all increase with size and age 
(Fitzhugh et al., 2012b; Lowerre-Barbieri et al., 2015; 
Porch et al., 2015). For many species, increasing age of 
mothers is also positively associated with egg and lar¬ 
val survival (Hixon et al., 2014) and there is evidence 
of a link between nutrition of reproductive females and 
egg and larval quality in red snapper (Papanikos et 
al., 2003, Bardon-Albaret and Saillant, 2017). There¬ 
fore, the age structure of recovering fish populations is 
an important management concern (Hixon et al., 2014, 
Barnett et al., 2017). A second condition, however, is 
