172 
Fishery Bulletin 120(2) 
A 
' a be study 
Ic area 
State-federal 
boundary 
Predicted spring 
abundance 
Gulf of Mexico 
BL study 
area 
State-federal 
boundary 
Predicted summer 
abundance 
Low 
Moderate 
; CL jet study 
area 
State-federal 
boundary 
Predicted autumn 
abundance 
Gulf of Mexico 
Figure 7 
Maps of the study area showing predicted relative abundance from 
boosted regression trees (BRTs) for red drum (Sciaenops ocellatus) col- 
lected in (A) spring, (B) summer, and (C) autumn during bottom longline 
(BL) surveys in the north-central Gulf of Mexico. Light shades indicate 
areas of low predicted abundance, and dark shades indicate areas of 
high predicted abundance. The dashed line that follows the coastline 
indicates the boundary between state and federal waters. Data used in 
the BRT analysis were from surveys conducted in 2006-2018. 
changes in relative abundance for this species 
are likely to be delayed and gradual. Conse- 
quently, continued fishery-independent monitor- 
ing is essential, both for characterizing changes 
in the population and for increasing the stabil- 
ity of catch advice generated from future stock 
assessments that apply the Islope approach 
(Sagarese et al., 2019). 
Management of red drum in the GOM cur- 
rently relies on each GOM state meeting an 
escapement goal (30%) of 4-year-old red drum 
(SEDAR, 2016). The premise of this management 
scheme is that most of these fish would enter 
the offshore adult population where the federal 
moratorium on GOM red drum protects the adult 
spawning stock. However, CPUE for adult red 
drum in the north-central GOM has been sub- 
stantially higher in state waters than in federal 
waters (Powers et al., 2012). Similar differences 
in CPUE between jurisdictions has been observed 
in other areas of the GOM (e.g., Winner et al., 
2014) and along the east coast of Florida (Reyier 
et al., 2011), particularly from August through 
November when adults return to state waters 
to spawn (Lowerre-Barbieri et al., 2016, 2019). 
These individuals travel to natal areas where 
they are targeted within spawning aggregations 
(Burnsed et al., 2020). 
Although state-level management of red drum 
is primarily focused on regulating the catch of 
juveniles by using slot limits, the current man- 
agement plans for 4 out of 5 GOM states (i.e., all 
GOM states except Florida) also afford oppor- 
tunities to keep a red drum larger than the slot 
limit. For example, landings data from the NOAA 
Marine Recreational Information Program (recre- 
ational fisheries statistics, available from website, 
accessed September 2021) indicate that nearly 
20% of red drum taken from Mississippi and 
Alabama state waters have been greater than 
762 mm FL (380 in FL), whereas no fish larger 
than this size have been landed in Florida (Fig. 8). 
Our findings clearly indicate that off the coast of 
Alabama, the federal moratorium does not pro- 
tect the larger, older age classes of red drum from 
exploitation. Adequately protecting these fish will 
require state management measures that either 
completely prohibit the catch of large individuals 
(e.g., as is done in Florida) or impose a tag system 
that allows a single over-slot fish per year (e.g., as 
is done in Texas). 
The catch data support the outputs from the 
BRTs, and the results of BRT analysis indicate 
that adult red drum prefer inshore, state waters. It 
has been long established that schools of spawning 
red drum aggregate near tidal passes (Low- 
erre-Barbieri et al., 2008; Reyier et al., 2011); the 
results of our analysis indicate a mechanistic 
explanation for this observation, confirming the 
