220 
National Marine 
Fisheries Service 
NOAA 
Abstract- —-Available tag-recapture and 
population genetics data for cobia 
(.Rachycentron canadum) in the south¬ 
eastern United States were evaluated 
to provide information on population 
structure and determine the geographic 
boundary between stocks in the Gulf 
of Mexico and the Atlantic Ocean. The 
movements of 1750 cobia were evalu¬ 
ated on the basis of assigned tagging 
and recapture zones. Genetic samples 
from an additional 2796 cobia collected 
during the presumed spawning season 
were genotyped at 10 microsatellite loci, 
and standard population genetic sta¬ 
tistical analyses were applied to the 
resulting sample data set. Tag-recapture 
results indicate that cobia tagged south 
of Cape Canaveral, Florida, primarily 
move between that area and the Gulf 
of Mexico and that cobia tagged north 
of Georgia have little interaction with 
the area south of Cape Canaveral. Cobia 
tagged at Cape Canaveral distributed 
widely throughout the entire southeast¬ 
ern coast of the United States. Genetic 
analysis results agree, indicating sep¬ 
arate stocks that occur from Texas 
through Hobe Sound on the east coast 
of Florida and from Savannah, Georgia, 
to the Chesapeake Bay in Virgina, with 
distinct genetic groupings within the 
Atlantic Ocean stock. The results indi¬ 
cate a transition area that occurs from 
Cape Canaveral through northern Geor¬ 
gia, and additional data from this region 
are necessary to further refine the stock 
boundary. 
Manuscript submitted 5 November 2018. 
Manuscript accepted 13 August 2019. 
Fish. Bull. 117:220-233 (2019). 
Online publication date: 23 August 2019. 
doi: 10.7755/FB. 117.3.9 
The views and opinions expressed or 
implied in this article are those of the 
author (or authors) and do not necessarily 
reflect the position of the National 
Marine Fisheries Service, NOAA. 
Fishery Bulletin 
established in 1881 -cf. 
Spencer F. Baird 
First U S. Commissioner 
of Fisheries and founder 
of Fishery Bulletin 
Evaluation of the stock structure of cobia 
(Rachycentron canadum ) in the 
southeastern United States by using 
dart-tag and genetics data 
Matt Perkinson (contact author ) 1 
Tanya Darden 1 
Maggie Jamison 1 
Matt J. Walker 1 
Michael R. Denson 1 
James Franks 2 
Read Hendon 2 
Susanna Musick 3 
Eric S. Orbesen 4 
Email address for contact author: perkinsonm@dnr.sc.gov 
1 Marine Resources Research Institute 
South Carolina Department 
of Natural Resources 
21 7 Fort Johnson Road 
Charleston, South Carolina 29412 
2 Gulf Coast Research Laboratory 
University of Southern Mississippi 
703 East Beach Drive 
Ocean Springs, Mississippi 39564 
3 Virginia Institute of Marine Science 
College of William and Mary 
PO. Box 1346 
Gloucester Point, Virginia 23062 
4 Southeast Fisheries Science Center 
National Marine Fisheries Service, NOAA 
75 Virginia Beach Drive 
Miami, Florida 33149 
The cobia (Rachycentron canadum ) is a 
large, migratory pelagic species found 
throughout most of the world’s tropical 
and subtropical waters, with the excep¬ 
tion of the eastern Pacific Ocean (Shaf¬ 
fer and Nakamura, 1989). In the United 
States, the species is found throughout 
the Gulf of Mexico (GOM) and Atlantic 
Ocean from Texas through Massachu¬ 
setts (Briggs, 1960), although catches 
north of the Chesapeake Bay in Virginia 
are less frequent. Life-history charac¬ 
teristics differ between cobia from the 
GOM and those from the western North 
Atlantic Ocean, with a faster growth 
rate in the GOM and a greater maxi¬ 
mum age in the Atlantic Ocean (Burns 
et al. 1 ). In the GOM, cobia undertake 
1 Burns, K. M., C. Neidig, J. Lotz, and 
R. Overstreet. 1998. Cobia (Rachycentron 
canadum ) stock assessment study in the 
Gulf of Mexico and in the South Atlan¬ 
tic. Mote Mar. Lab. Tech. Rep. 571, 108 p. 
[Available from website.] 
seasonal migrations from overwintering 
grounds in South Florida to spawning 
grounds in the northern GOM during 
spring and summer (Bums and Nei¬ 
dig 2 ; Ditty and Shaw, 1992; Biesiot et al., 
1994; Franks and Brown-Peterson, 
2002; Dippold et al., 2017), although 
some cobia may migrate from deeper off¬ 
shore overwintering grounds to coastal 
areas as well (Hendon and Franks 3 ). In 
the western North Atlantic Ocean, cobia 
enter high-salinity estuaries as well as 
nearshore locations in Georgia, South 
2 Bums, K. M., and C. L. Neidig. 1992. Cobia 
(Rachycentron canadum ), ambeijack (Seriola 
dumerili), and dolphin (Coryphaena hipurus ) 
migration and life history study off the south¬ 
west coast of Florida. Mote Mar. Lab. Tech. 
Rep. 267,58 p. [Available from website.] 
3 Hendon, J. R., and J. S. Franks. 2010. Sport 
fish tag and release in Mississippi coastal 
waters and the adjacent Gulf of Mexico, 13 p. 
Final Rep., Proj. F-132, Segments 7-9. Gulf 
Coast Res. Lab., Univ. South. Miss., Ocean 
Springs, MS. [Available from website.] 
