Hightower et al.: Population dynamics and relative abundance for adult Sc@enops ocellatus 173 
Mississippi/Alabama 
305 457 610 
Florida 
Frequency (%) 
T 
T T T 
762 914 
Fork length (mm) 
Figure 8 
Length—frequency distributions for red drum (Sciaenops ocella- 
tus) caught in waters off Mississippi and Alabama and off Florida 
between 2006 and 2018. Data are from the NOAA Marine Recre- 
ational Information Program. The vertical dashed line represents 
size at 50% maturity, reported by Bennetts et al. (2019). 
importance of surface current velocity when defining suit- 
able habitat for red drum. Temperature is also a well known 
and strong predictor of habitat use of red drum. In previous 
work in this region, bimodal peaks in relative abundance in 
the spring and autumn were documented as was the corre- 
spondence of these seasonal peaks to temperatures of 21°C 
and 20°C, respectively (Powers et al., 2012), which are con- 
sistent with the temperatures identified in this study as 
those preferred by red drum. On the basis of habitat suit- 
ability predictions from the BRTs, we speculate that during 
the summer, adult red drum may be using deep (>30 m), 
cool (~20°C) waters as a thermal refuge. 
Conclusions 
Clearly, assessing a stock under a complete catch morato- 
rium presents distinct challenges. Nonetheless, when the 
data typically used to assess the status of a stock (e.g., 
commercial catch data) are lacking, an opportunity exists 
to consider alternative data sources, which can some- 
times provide new information about stock dynamics 
(Olney and Hoenig, 2001). Such is the case for 
GOM red drum. In addition to updated ages, 
growth models, and M estimates, the results of 
our investigation reveal that the adult spawn- 
ing stock is not fully protected by the federal 
catch moratorium. Moreover, through use of our 
habitat suitability models, we identified factors 
that may predict suitable habitat for red drum 
in other regions of the GOM. Collectively, the 
findings from this study, in concert with those 
from future efforts to combine nearshore indi- 
ces of relative abundance from standardized 
bottom longline surveys throughout the region 
(e.g., the surveys of the Southeast Area Moni- 
toring and Assessment Program), will be critical 
for advancing the stock of red drum in the GOM 
from its status as data-limited. 
Acknowledgments 
We thank Dauphin Island Sea Lab captains and 
crew, especially Captains T. Guoba and J. Witt- 
mann, for their help with the bottom longline sur- 
vey. We thank A. Kroetz, T. Spearman, T. Nelson, 
and others for their help with field collections, 
otolith processing, and aging. Thanks to the 
Marine Resources Division, Alabama Depart- 
ment of Conservation and Natural Resources, 
for collecting and sharing data on red drum 
from gill-net surveys. This work was conducted 
in accordance with Institutional Animal Care 
and Use Committee protocol no. 1562086 and 
was funded in part by the Gulf of Mexico Fish- 
ery Management Council. 
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