Gold and Richardson: Population structure of Seriola dumerih 
769 
ranged from 24 to 58 individuals. Individuals were 
sampled variously from charter boats, headboats, and 
commercial fishing boats, and from catches of recre- 
ational fishers at tournaments. Tissues were removed 
from each specimen, quickly frozen in liquid nitro- 
gen, and transported to Texas A&M University where 
they were stored at -80°C in an ultracold freezer. 
Methods (including DNA extraction, precipitation, 
and storage) used to assay restriction-enzyme frag- 
ment patterns of mtDNA molecules of individual fish 
followed those described in Gold and Richardson 
(1991). Sixteen, type-II restriction-endonuclease en- 
zymes were used to digest 1.0-1. 5 pg of DNA in 40 
pL reactions according to manufacturer’s specifica- 
tions. Enzymes used were ApaLI, Apal, EcoRI, 
EcoKV, iTmdIII, Hpal, Ncol , Pstl, Pvull, Seal, Smal, 
Spe I, Sspl, Sstl, Stul, and Xbal. Methods of DNA 
digestion, agarose electrophoresis, transfer to nylon 
filters (after Southern, 1975), hybridization, and 
autoradiography also followed those in Gold and 
Richardson (1991). Hybridization employed a 12.5 
kilobase (kb) fragment of greater amberjack mtDNA 
cloned into lambda bacteriophage (Richardson and 
Gold, 1993). Bacteriophage lambda DNA digested 
with restriction enzyme Hindlll was employed as a 
molecular weight marker on each gel. MtDNA frag- 
ments produced by single digestion of greater am- 
berjack mtDNA were sized by fitting migration dis- 
tances to a least-squares regression of lambda DNA- 
Hi TzdIII fragment migration distances. Single 
digestion mtDNA-fragment patterns were used to 
TabSe 1 
Sample localities of greater amberjack (Seriola dumerili). 
Locality j 
Number of individuals 
Port Aransas, Texas (PA) 
58 
Freeport, Texas (FP) 
44 
Port Fourchon, Louisiana (PF) 
43 
Gulfport, Mississippi (GP) 
7 
Pensacola, Florida (PN) 2 
24 
Panama City, Florida (PC) 
50 
St. Petersburg, Florida (SP) 
42 
Sarasota, Florida (SR) 2 
32 
Florida Keys (FK) 
55 
New Smyrna Beach, Florida (NS) 
53 
South Carolina (SC) 
36 
Total 
444 
1 Localities represent dock sites where individuals sampled off- 
shore were off-loaded. Individuals from the Florida Keys were 
off-loaded at Islamorada; individuals from South Carolina were 
off-loaded at several localities. 
2 Previously examined by Richardson and Gold (1993). 
generate composite digestion patterns (mtDNA 
haplotypes). 
Analysis of mtDNA data was facilitated by the 
Restriction Enzyme Analysis Package (REAP) of 
McElroy et al. (1992). Genotypic (nucleon) diversity 
within sample localities was calculated following Nei 
and Tajima (1981) and was based on the total num- 
ber of mtDNA haplotypes identified within a local- 
