Powers et at: Age composition and distribution of Sciaenops ocellatus in offshore waters of the north central Gulf of Mexico 
287 
and Alabama from 2006 through 2010 (Fig. 
IB). The highest concentrations of fish were 
collected near the pass between Dauphin 
Island and Ft. Morgan (mouth of Mobile Bay) 
and offshore Petit Bois Island. Twenty-four 
percent of sets produced red drum, and a 
maximum of 23 individuals were captured 
during a single set (October 2007). Standard- 
ized mean monthly CPUE for red drum was 
bimodal with the greatest concentrations of 
fish captured in March (2.7 fish-100 hooks -1 
hour 1 ) and April (2.3 fish-100 hooks -1 hour -1 ) 
followed by November (1.5 fish-100 hooks - 
'hour -1 ). Mean monthly temperatures followed 
a predictable seasonal pattern, ranging from a 
low of 12.3°C in February to 31.7°C in August 
(Fig. 2). The majority of red drum were col- 
lected in water <20 m deep, although effort 
was high throughout waters <60 m deep. The 
maximum depth red drum were collected from 
was 63 m. 
In general, red drum distributions revealed 
in the aerial surveys complemented the spa- 
tial distribution patterns determined from the 
bottom longline gear. Red drum schools were 
spotted during 8 out of 13 aerial surveys. All red 
drum schools were spotted west of Mobile Bay 
(88°W longitude), many near the barrier islands 
of the ncGOM. Sightings occurred most frequently 
in the shallow waters around Dauphin Island and 
Petit Bois Island, and around the Chandeleur 
Islands (Fig. ID). 
Length, age, and growth of red drum 
Length-frequency distributions differed between 
the longline- and ADSFR-collected fish. The mean 
(±standard error [ SE ] TL) of the 428 red drum 
collected on the bottom longline was 912 (± 3.0) 
mm with a range of 720 mm to 1101 mm TL (Fig. 
3A). For the 176 red drum collected at the ADSFR, 
the mean total length was 849 mm with a range 
between 660 and 1156 mm TL (Fig. 3B). Fish 
collected on longlines were significantly longer 
than the fish captured at the ADSFR (two-sample 
KS test, D = 0.416, P<0.0001). Males and females 
were analyzed separately for length differences. 
Females were longer than males for both bottom 
longlines and ADSFR. Mean total length for 
bottom longline females (n = 114) was 923 (±6.09) 
and 885 (±6.23) for males (n = 99). For the ADSFR, 
mean total length for females (/z = 106 ) was 870 
(±12.25) and 811 (±15.03) for males (n = 67). 
Ages were determined for both fishery-indepen- 
dent and fishery-dependent collections. Average 
percent error for the two readers was 0.004%, in- 
dicating precise aging. No otoliths were excluded owing 
to a discrepancy in counts of annuli. The mean (±SE) 
age for fish caught on the longline was 16.5 (±0.4) years 
with a range of 2-34 years (Fig. 4A). For fish sampled 
13 
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o 
3 0 
JZ 
o 
o 
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2.0 
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Figure 2 
Mean monthly catch per unit of effort (CPUE |±standard error, 
SE], line) and temperature (±SE, bar) for longline-caught red 
drum ( Sciaenops ocellatus ), May 2006-May 2010. 
cV 
cp c^ 5 Qp rV 
Total length (mm) 
Figure 3 
(A) Length frequency of red drum ( Sciaenops ocellatus) sampled 
on the fisheries-independent longlines (2006-10) and (B) at the 
fisheries-dependent Alabama Deep Sea Fishing Rodeo (2009). 
at the ADSFR, age composition ranged from 2 to 38 
years. The mean age of an ADSFR fish was 9 years; 
however, 50% of fish collected were in the 2-4 year 
category (Fig. 4B). For longline fish, the age frequency 
