Darden et al : Population genetics of Rcichycentron canadum 
29 
Table 4 
Mendelian inheritance statistics for two independent families of Cobia ( Rachycentron 
canadum)-. chi-square <x 2 ) values, degrees of freedom (df), and P-values at each of the 10 
Cobia-specific microsatellite loci. For two loci in family 2, both parents were homozygous 
for different alleles and all offspring were fixed heterozygotes, as expected (an asterisk 
indicates each of these loci). 
Locus 
Family 1 
Family 2 
X 2 
df 
P-value 
X 2 
df 
P-value 
Rcal-HIO 
2.27 
1 
0.131 
1.33 
1 
0.248 
Rcal-A04 
0.09 
1 
0.764 
0.50 
2 
0.778 
RcalB-E02 
2.27 
1 
0.131 
0.00 
1 
1.000 
Real-All 
4.40 
3 
0.221 
1.00 
1 
0.317 
RcalB-H09 
0.00 
1 
1.000 
5.33 
2 
0.069 
RcalB-E08A 
1.80 
2 
0.406 
* 
- 
- 
RcalB-C06 
3.00 
3 
0.391 
2.45 
3 
0.484 
RcalB-DIG 
1.00 
3 
0.801 
0.40 
1 
0.527 
Real-Ell 
1.22 
2 
0.543 
* 
- 
- 
Rcal-C04 
0.00 
1 
1.000 
3.89 
3 
0.273 
varied, adhere to the expectations of Mendelian in- 
heritance, distinguish between related individuals, and 
correctly match offspring to their parents with a high 
degree of confidence. 
Movement and estuarine fidelity 
No fish collected outside of SC were genetically iden- 
tified as SC-stocked fish; therefore our evaluation of 
hatchery contribution represents their contribution to 
SC Cobia populations. Parentage analysis of 341 sam- 
ples identified two fish in the SC 2008 collections that 
were both originally stocked in 2004 into Port Royal 
Sound. On the basis of otolith aging, 174 fish from the 
2004 year class (YC) were present in the SC 2008 col- 
lections. Therefore, the 2004 stocked fish made a 1.1% 
contribution to the SC 2004 YC of Cobias. A large num- 
ber of the SC 2008 samples, including the two recap- 
tured stocked fish, were missing specific collection de- 
tails. Without these details, we were unable to assign 
samples to inshore and offshore groups. Therefore, the 
year-class contribution was estimated on the basis of 
all SC samples — an assessment that likely underesti- 
mated the true contribution. From the 2008 samples, 
the 2004 YC stocked fish represented 0.6% of all SC- 
collected samples. 
From the 2009 collections (n=232), 11 stocked fish 
were identified, all from the 2007 YC small juvenile 
stockings in Port Royal Sound. Thirteen 2007 YC fish 
were identified in the 2009 collections, resulting in an 
84.6% contribution of stocked fish to the SC Cobia 2007 
YC and a 4.7% contribution to the overall SC popula- 
tion of sampled Cobias. Of the identified stocked fish, 
8 were recaptured within the Port Royal Sound estu- 
ary, and the remaining 3 recaptured stocked fish did 
not have sufficient collection information for group as- 
signment. In addition to the recapture of stocked fish 
in their release estuary, one wild fish was recaptured 
within the Port Royal Sound estuary in multiple years 
(this finding was based on genetic identity analyses — 
see previous section). No wild recaptures were detected 
among different collection locations. Although these 
recaptures were represented by low sample sizes, the 
pattern of site fidelity among all recapture groups was 
consistent. 
For external tag recaptures, 7 tag returns were re- 
ported from the 2004 YC of stocked yearling Cobias 
(93 originally stocked; Table 5). Within 32 days after 
release (mean of 25 days at large), 5 of the fish were 
recaptured, and 1 fish was recaptured later that sum- 
mer; however, the remaining fish was recaptured the 
following spring after 370 days at large. All tag returns 
of 2004 YC fish were recaptured within the SC inshore 
area. From the 2005 YC fish that were stocked with ex- 
ternal tags (n=385), 58 were recaptured over a 3-year 
period. Two of these recaptures were reported with no 
collection information. Within 40 days after release 
(mean of 17 days at large), 44 of the 2005 YC fish were 
recaptured, and all of the fish that were reported with 
location information were recaptured within the SC in- 
shore area. Of the remaining fish, 7 were recaptured 
within the SC inshore area 2-3 years after their stock- 
ing during the spawning season; these fish had a mean 
of 813 days at large. The final 5 fish were recaptured 
