NOTE Blandon et al.: Genetic population structure of Parcilichthys lethostigmci 
677 
In our study, allele frequency discontinuities and clinal 
variation in genetic characters were identified among 
southern flounder inhabiting the western portion of the 
species’ range. Short-term goals (e.g. supplementing ex- 
ploited populations) that fail to account for this structur- 
ing could result in management programs that undermine 
the long-term resource management objective: maintain- 
ing the evolutionary potential of this species. The results 
of this survey suggest that southern flounder populations 
should be considered potentially distinct pending further 
resolution of population differentiation and clinal varia- 
tion. Stocking efforts, especially those involving interbay 
transfers, should be undertaken only after careful consid- 
eration of all pertinent information, and be contingent up- 
on careful studies of genetic variation at the appropriate 
local level. Observed discontinuities and clinal variations 
in allele frequencies may indicate adaptation to localized 
conditions and should be incorporated into comprehensive 
management strategies developed for southern flounder. 
Acknowledgments 
Financial support for this research was received from the 
Sport Fish Restoration Program of the U. S. Fish and Wild- 
life Service. Field personnel of the TPW Coastal Fisheries 
Division provided invaluable assistance in sample collec- 
tion. Additional samples were provided by Greg Stunz 
of Texas A&M University, and Bradley Randall and his 
colleagues in the Fishery Department of the Gulf Coast 
Research Laboratory of Ocean Springs, Mississippi. We 
thank Larry McEachron and Bob Colura for administra- 
tive support and assistance with sample collection, and 
Roberta Vickers, David Westbrook, and Eric Young for 
their laboratory assistance, as well as Andrew Shaw for 
the preparation of Figure 1. 
Literature cited 
Allendorf, F. W., N. Ryman, and F. M. Utter. 
1987. Genetics and fishery management: past, present, and 
future. In Population genetics and fishery management 
(N. Ryman and F. Utter, eds.), p. 1-19. Univ. Washington 
Press, Seattle, WA. 
Banks, M. A., and W. Eichert. 
2000. WHICHRUN (version 3.2) a computer program for 
population assignment of individuals based on multilocus 
genotype data. J. Hered. 91:87-89. 
Cavalli-Sforza, L. L., and A. W. F. Edwards. 
1967. Phylogenetic analysis: models and estimation proce- 
dures. Am. J. Hum. Gen. 19:233-257. 
Cochrane, J. D., and F. J. Kelly. 
1986. Low-frequency circulation on the Texas-Louisiana 
continental shelf. J. Geophys. Res. 91:10645-10659. 
Cockerham, C. C. 
1969. Variance of gene frequencies. Evolution 23:72-83. 
1973. Analysis of gene frequencies. Genetics 74:679-700. 
Cornuet, J.-M., S. Piry, G. Luikart, A. Estoup, and M. Solignac. 
1999. New methods employing multilocus genotypes to se- 
lect or exclude populations as origins of individuals. Genet- 
ics 153:1989-2000. 
Ginsburg, I. 
1952. Flounders of the genus Paralichthys and related 
genera in American waters. Fish. Bull. 52:267-351. 
Gold, J. R., T. L. King, L. R. Richardson, D. H. Bohlmeyer, and 
G. C. Matlock. 
1994. Genetic studies in marine fishes. VII: allozyme differ- 
entiation within and between red drum ( Sciaenops ocella- 
tus) from the Gulf of Mexico and Atlantic Ocean. J. Fish 
Biol. 116:517-185. 
Gold, J. R., and L. R. Richardson. 
1999. Population structure of two species targeted for 
marine stock enhancement in the Gulf of Mexico. Bull. 
Natl. Res. Inst. Aquacult. (suppl. 1 ):79-87. 
IUBMBNC (International Union of Biochemistry and 
Molecular Biology, Nomenclature Committee). 
1992. Enzyme nomenclature. Academic Press, Orlando, 
Florida, 862 p. 
Kimura, M., and G. H. Weis. 
1964. The stepping stone model of population structure and 
the decrease of genetic correlation with distance. Genet- 
ics 49:561-576. 
King, T. L., and H. O. Pate. 
1992. Population structure of spotted seatrout inhabiting 
the Texas Gulf coast: an allozymic perspective. Trans. Am. 
Fish. Soc. 121:746-756. 
King, T. L., R. Ward, I. R. Blandon, R. L. Colura, and J. R. Gold. 
1995. Using genetics in the design of red drum and spotted 
seatrout stocking programs in Texas: a review. In Uses 
and effects of cultured fishes in aquatic ecosystems (H. L. 
Schramm Jr. and R. G. Piper, eds.), p. 499-502. Am. Fish. 
Soc. Sym. 15, Am. Fish. Soc., Bethesda, MD. 
King, T. L., R. Ward, and E. G. Zimmerman. 
1994. Population structure of eastern oysters (Crassostrea 
virginica) inhabiting the Laguna Madre, Texas and adja- 
cent bay systems. Can. J. Fish. Aquat. Sci. 51:215-222. 
King, T. L., and E. G. Zimmerman. 
1993. Clinal variation at aspartate aminotransferase-2 in 
spotted seatrout, Cynoscion nebulosus (Cuvier), inhabiting 
the north-western Gulf of Mexico. Anim. Gen. 24:59-61. 
Manchenko, G. P. 
1994. Handbook of detection of enzymes on electrophoretic 
gels. CRC Press, Boca Raton, FL, 341 p. 
Mantel, N. A. 
1967. The detection of disease clustering and a generalized 
regression approach. Cancer Res. 27:209-220. 
Nelson, K., and M. Soule. 
1987. Genetical conservation of exploited fishes. In Popu- 
lation genetics and fishery management (N. Ryman and F. 
Utter, eds.), p. 345-368. LTniv. Washington Press, Seattle, 
WA. 
Page. D. D. M. 
1996. TREEVIEW: an application to display phylogenetic 
trees on personal computers. Comput. Appl. Biosci. 12: 
357-358. 
Raymond, M., and F. Rousset. 
1995. GENEPOP (version 1.2): population genetics software 
for exact tests and ecumenism. J. Heredity 86:248-249. 
Rice, W. R. 
1989. Analyzing tables of statistical tests. Evolution 43: 
223-225. 
Rohlf, F. J. 
1997. NTSYS-pc: numerical taxonomy and multivariate 
analysis system, version 2.0. Exeter Software, Setauket, 
NY, 32 p. 
Sackler, M. L. 
1966. Xanthine oxidase from liver and duodenum of the rat: 
