Dippold et al.: Growth, mortality, and movement of Rachycentron canadum 
467 
Table 3 
Estimates of von Bertalanffy growth function parameters for cobia (Rachycentron canadum) from previously published stud¬ 
ies and this study. The 3 parameters are mean asymptotic length (L„), provided as millimeters in fork length (FL), annual 
growth coefficient (k), and hypothetical age at length of zero (t 0 ). For parameter values, standard errors of the mean are pro¬ 
vided for some studies and the 95% confidence intervals (CIs) are provided for this study in parentheses. The locations were 
Virginia (VA), Louisiana (LA), North Carolina (NC), the northeastern Gulf of Mexico (nGOM), and the Gulf of Mexico (GOM). 
Study 
Location 
Sex 
n 
(mm FL) 
k 
t 0 (years) 
Richards, 1967 
VA 
M 
88 
1210 
0.28 
-0.06 
F 
135 
1640 
0.23 
-0.08 
Thompson et al. 9 
LA 
M 
464 
1132 
0.49 
-0.49 
F 
218 
1294 
0.56 
0.11 
Smith, 1995 
NC 
M 
116 
1050 (18.5) 
0.37 (0.04) 
-1.08 (0.29) 
F 
92 
1350 (38.2) 
0.24 (0.03) 
-1.53 (0.39) 
Franks et al., 1999 
nGOM 
M 
170 
1171(28.1) 
0.43 (0.05) 
-1.15 (0.17) 
F 
395 
1555 (35.1) 
0.27 (0.02) 
-1.25 (0.09) 
SEDAR 1 
GOM 
combined 
1282 
0.42 
-0.53 
SEDAR 1 
Atlantic Ocean 
combined 
2485 
1324 
0.27 
-0.47 
This study 
GOM 
combined 
926 
1172 (1151-1192) 
0.57 (0.52-0.61) 
NA 
Movement and seasonal distribution 
Movement among zones Seven geographic zones were 
defined in our study to determine the large-scale and 
seasonal movements of cobia (Fig. 1). Large-scale 
movement patterns of cobia in the Gulf of Mexico and 
South Atlantic Ocean were observed. Notably, a por¬ 
tion of the individuals tagged in the Florida Keys, 
Florida panhandle, Louisiana, and northcentral Gulf 
of Mexico zones were recaptured in the South Atlan¬ 
tic Ocean zone and therefore indicated that cobia mi¬ 
grate around Florida between the Gulf of Mexico and 
South Atlantic Ocean (Table 4). Individuals tagged in 
the Texas zone were recaptured only in the Louisiana 
and Texas zones and thus indicated that cobia in the 
western Gulf of Mexico may exhibit limited movement 
or could be a resident group (Table 4). However, it 
is important to note that a relatively low number of 
individuals were tagged and recaptured in the Texas 
zone over the entire duration of the tagging program 
(227 tagged, 40 recaptured, Table 1). A majority of in¬ 
dividuals tagged in a given zone were recaptured in 
the same zone for all zones except the Florida pan¬ 
handle zone where the majority of recaptures were 
distributed among the Florida panhandle, Louisiana, 
and northcentral Gulf of Mexico zones (Table 4). Un¬ 
fortunately, because of the lack of resolution in the re¬ 
ported tagging and recapture locations, we could not 
evaluate how time-at-liberty affects individual move¬ 
ment between zones. 
Table 4 
A matrix of the number and proportion of cobia (Rachycentron canadum) (n=875, time-at-liberty >30 days) tagged and 
recaptured in the Gulf of Mexico and South Atlantic Ocean during 1988-2014 and the recapture percentage among the 7 
geographic zones used in this study. The zones are the 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 of recapture Recapture percentage 
Zone of 
tagging 
ATL 
FLGC 
FLK 
FLPH 
LA 
NcGOM 
TX 
Total 
ATL 
FLGC 
FLK 
FLPH 
LA 
NcGOM 
TX 
ATL 
30 
0 
5 
2 
1 
2 
0 
40 
0,75 
0 
0.12 
0.05 
0.02 
0.05 
0 
FLGC 
0 
30 
7 
6 
2 
1 
0 
46 
0 
0.65 
0.15 
0.13 
0.04 
0.02 
0 
FLK 
6 
9 
63 
18 
4 
7 
1 
108 
0.06 
0.08 
0.58 
0.17 
0.04 
0.06 
0.01 
FLPH 
30 
9 
24 
73 
61 
63 
16 
276 
0.11 
0.03 
0.09 
0.26 
0.22 
0.23 
0.06 
LA 
3 
1 
3 
5 
41 
3 
5 
61 
0.05 
0.02 
0.05 
0.08 
0.67 
0.05 
0.08 
NcGOM 
15 
10 
33 
55 
35 
184 
7 
339 
0.04 
0.03 
0.1 
0.16 
0.1 
0.54 
0.02 
TX 
0 
0 
0 
0 
1 
0 
4 
5 
0 
0 
0 
0 
0.2 
0 
0.8 
Total 
84 
59 
135 
159 
145 
260 
33 
875 
