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Fishery Bulletin 1 12(4) 
Although red snapper in the GOM currently are 
managed as a single unit stock, separate stock assess- 
ments have been conducted since 2004 for subunits 
east and west of the Mississippi River (SEDAR 1 ). Un- 
der the single-unit-stock hypothesis, no significant dif- 
ferences are assumed in population structure (genet- 
ics and population demographics) across the GOM. 
The single-unit-stock assumption has been supported 
by genetic analysis (Camper et ah, 1993; Gold et ah, 
1997; Gold et al., 2001; Saillant et al., 2010), by the po- 
tential for high larval dispersal through hydrodynamic 
transport (Johnson et al., 2009), and by the capacity of 
adult red snapper to move great distances (>100 km) 
and, therefore, to potentially maintain mixing rates 
(Patterson et al., 2001a). Also, in the past 20 years, 2 
strong year classes (1989 and 1995) were found to dom- 
inate catches GOM-wide (Allman and Fitzhugh, 2007), 
strengthening the single-unit-stock hypothesis. 
In the recent decade, however, numerous studies 
have highlighted spatial differences in age, growth, and 
reproductive demographics between eastern and west- 
ern red snapper (Allman et al., 2002; Fischer et al., 
2002, 2004; Jackson et al., 2007). Studies of the popu- 
lation structure of red snapper genetics and movement 
indicate that GOM fish form a metapopulation of semi- 
isolated, subpopulations (Saillant and Gold, 2006; Gold 
and Saillant, 2007; Patterson, 2007), and recent genetic 
evidence indicates that the Caribbean red snapper (L. 
puj-pureus) and the red snapper (L. campechanus) may 
not be separate species (Gold et al., 2011; Gomes et 
al., 2012). Examination of otolith microchemistry also 
has shown region-specific natural tags or elemental 
signatures, which have been used to identify nursery 
sources, subpopulations, and to provide evidence of 
stock mixing across the GOM (Patterson et al., 2008; 
Nowling et al., 2011; Sluis et al., 2012). 
In this study we sought to complement similar mea- 
sures reported by Fischer et al. (2004) for a previous 
study and to expand upon the area that they studied 
in order to encompass more regions. The updated infor- 
mation from our study is important for identification 
of region-specific trends and changes in the red snap- 
per fishery. Our objectives were 1) to examine the size 
structure, growth rates, and size at age of red snapper 
in the GOM to elucidate trends in demographic differ- 
ences noted in the most recent stock assessments (SE- 
DAR 5 ), 2) to expand the comparison to incorporate red 
snapper off Florida, and 3) to identify region-specific 
trends in the recreational red snapper fishery. 
Materials and methods 
Red snapper were sampled from recreational hook- 
and-line fisheries (head boats and charter boats) in 6 
regions of the GOM during 2009 and 2010 (Fig. 1) and 
were identified by using characteristics from Hoese and 
Moore (1998). In each region and year, a maximum of 
200 fish were sampled from the daily catches of recre- 
ational vessels. Fish were selected haphazardly while 
the vessels offloaded. Sample size varied with trip size, 
and the number of vessels sampled in each region was 
dependent upon the size of the regional fleet. To obtain 
samples representative of the fishery in each region 
and to maximize the number of vessels and trips sam- 
pled, collection occurred during a period of 3-5 days 
each year. Samples were not selected from the commer- 
cial fishery because of the market preference for fish 
close to 330 mm in total length. During 2010, recre- 
ational fisheries in Alabama and Louisiana were not 
sampled because these fisheries were closed as a result 
of the Deepwater Horizon Oil Spill. Louisiana samples 
were supplemented in 2010 with fish collected by hook 
and line from 2 oil platforms, which are sites routinely 
fished by recreational and commercial fishermen, in the 
GOM about 110 km south of the Louisiana coast. For 
all fish collected, morphometric measurements (natu- 
ral total length [TL] in millimeters and total weight 
[TW] in kilograms) were recorded, sex was determined 
by macroscopic examination of gonads (when possible), 
and sagittal otoliths were removed, rinsed, and stored 
in coin envelopes until processed. 
The left sagittal otolith was sectioned in a transverse 
plane following the methods of Cowan et al. (1995) 
with a Hillquist Thin Section Machine, Model 800 6 
(Hillquist Inc., Denver, CO), equipped with a diamond- 
embedded watering blade and precision grinder. Otolith 
sections (0.2-mm thick) were read under a dissecting 
microscope with transmitted light and a polarizing 
light filter at a magnification from 20x to 64x. Counts 
of opaque annuli were made along the dorsal margin 
of the sulcus acousticus from the core to the proximal 
edge (Wilson and Nieland, 2001). Edge condition of the 
dorsal margin was coded according to Beckman et al. 
(1988). Annuli were counted by 2 independent readers 
without knowledge of date and location of capture or 
access to morphometric data of the specimens. When 
initial counts disagreed, annuli were counted a second 
time. In instances where a consensus between the 2 
readers could not be reached, the annulus counts from 
the more experienced reader were reported. Precision 
between readers was evaluated with the coefficient of 
variation (CV), index of precision (D) (Chang, 1982), 
and average percent error (APE) (Beamish and Fourni- 
er, 1981). Ages of red snapper were estimated from the 
number of opaque annuli, assumed birthdate, and cap- 
ture date, by following the equation described by Wil- 
son and Nieland (2001): 
Age (days) = -182 + (annulus count x 365) 
+ ((m - 1) x 30) + d, (1) 
where m = the ordinal number (1-12) of month of cap- 
ture; and 
6 Mention of trade names or commercial companies is for iden- 
tification purposes only and does not imply endorsement by 
the National Marine Fisheries Service, NOAA. 
