466 
Fishery Bulletin 11 5(4) 
Figure 4 
Histograms of length frequency for cobia (Rachycentron canadum) at tagging, and recapture , and 
time at liberty from time of tagging to time of recapture in the Gulf of Mexico and South Atlantic 
Ocean during 1988-2014. 
Table 1 
Total number of cobia (Rachycentron canadum) tagged 
and recaptured during 1988-2014 in each of 7 geo¬ 
graphic zones in the Gulf of Mexico and South Atlantic 
Ocean. The 7 zones are South Atlantic Ocean (ATL), 
Florida Gulf Coast (FLGC), Florida Keys (FLK), Florida 
panhandle (FLPH), Louisiana (LA), northcentral Gulf of 
Mexico (NcGOM), and Texas (TX). 
Zone 
Tagged 
Recaptured 
ATL 
557 
90 
FLGC 
961 
73 
FLK 
1518 
189 
FLPH 
4620 
190 
LA 
1703 
166 
NcGOM 
8112 
373 
TX 
227 
40 
(0.57/year [95% Cl: 0.52-0.61]) was lower than the val¬ 
ues from both the Fabens VBGF model (0.62/year [95% 
Cl: 0.56-0.69]) and the Gompertz model (0.84/year 
[95% Cl: 0.77-0.92]). The estimated value of from 
the GROTAG VBGF model was in the range of values 
reported from Virginia, Louisiana, North Carolina and 
the Gulf of Mexico (Richards, 1967; Thompson et al. 9 ; 
Smith, 1995; Franks et ah, 1999; Table 3). However, 
the estimate of k was higher in our analysis than those 
values reported for Virginia, North Carolina and the 
Gulf of Mexico (Table 3). The closest values to those es¬ 
timated in this study were the estimates of k reported 
from Louisiana (Thompson et al. 9 ). In the most recent 
Gulf of Mexico and South Atlantic Ocean assessments, 
the models used to describe length-at-age relationships 
were also sex aggregated (SEDAR 1 ), however the esti¬ 
mates of L r _„ in the SEDAR assessments were greater 
than the estimate in our study and the SEDAR esti¬ 
mates of k were lower than the value estimated in our 
study (Table 3). 
Table 2 
Parameter estimates, with 95% confidence intervals, from nonlinear models fitted to informa¬ 
tion on tagging and recapture of cobia (Rachycentron canadum) in the Gulf of Mexico and South 
Atlantic Ocean during 1988-2014. The mean asymptotic length (L<J, provided as millimeters in 
fork length (CI=confidence interval), and the annual growth coefficient ( k ) were estimated for 2 
parameterizations of the von Bertalanffy growth function (VBGF) and a Gompertz model. The 2 
parameterizations were the VBGF used in the program GROTAG and the VBGF used by Fabens 
(1965). The relative model support was evaluated by using Akaike’s information criterion (AIC), 
and Akaike weight (u>d was calculated for each model. 
Model 
L„(CI) 
k 
AAIC 
W 1 
GROTAG VBGF 
1172 (1151-1192) 
0.57 (0.52-0.61) 
0.00 
1.00 
Fabens VBGF 
1189(1163-1219) 
0.62 (0.56-0.69) 
119.70 
0.00 
Gompertz 
1157 (1135-1181) 
0.84 (0.770.92) 
153.80 
0.00 
