Abstract. Red drum, 



Sciaenops ocellatus, from Mosquito 

 Lagoon, east-central Florida, were 

 examined for variation in products 

 of nine polymorphic nuclear-gene 

 (allozyme) loci and in mitochon- 

 drial (mt)DNA restriction sites. 

 Genetic data from Mosquito La- 

 goon fish were compared to simi- 

 lar data from red drum sampled 

 from the northeastern Gulf of 

 Mexico (Gulf) and the Carolina 

 coast of the southeastern United 

 States. Significant heterogeneity 

 among red drum from the three 

 areas was found in the frequencies 

 of inferred alleles at two to three 

 allozyme loci and in the frequen- 

 cies of six mtDNA haplotypes. Red 

 drum from Mosquito Lagoon were 

 as differentiated genetically from 

 red drum in the northeastern Gulf 

 and Carolina coast as the latter 

 two were from each other. Genetic 

 data are consistent with the hy- 

 pothesis that red drum in Mos- 

 quito Lagoon are self-contained 

 and at least partially isolated from 

 red drum in other U.S. waters. 



Genetic distinctness of red drum 

 (Sciaenops ocellatus) from 

 Mosquito Lagoon, 

 east-central Florida* 



John R. Gold 



Department of Wildlife and Fisheries Science 

 Texas A&M University, College Station. Texas 77843 



Linda R. Richardson 



Department of Wildlife and Fisheries Science 

 Texas A&M University. College Station, Texas 77843 



Manuscript accepted 17 August 1993 

 Fishery Bulletin: 92:58-66 (1994) 



Over the past five years, our labo- 

 ratory has carried out studies of 

 spatial and temporal genetic varia- 

 tion among red drum (Sciaenops 

 ocellatus) from the northern Gulf of 

 Mexico (Gulf) and the Carolina 

 coast of the southeastern United 

 States (Bohlmeyer and Gold, 1991; 

 Gold and Richardson, 1991; Gold et 

 al., 1993, in press). Red drum cur- 

 rently support important recre- 

 ational fisheries in both the north- 

 ern Gulf and U.S. Atlantic (Mat- 

 lock, 1984; Mercer, 1984), and both 

 fisheries are now regulated to re- 

 duce growth and recruitment over- 

 fishing (Swingle et al., 1984 1 ; 

 Goodyear, 1989 2 ). Collectively, our 

 genetic data have indicated that 

 red drum in U.S. waters are sub- 

 divided with weakly differentiated 

 subpopulations in the northern 

 Gulf and along the Carolina coast. 

 No genetic heterogeneity has been 

 found among red drum from differ- 

 ent localities within either the 

 northern Gulf or Carolina coast 

 (Gold et al., 1993, in press). The ge- 

 netic data are consistent with sev- 

 eral aspects of red drum biology 

 and life history that suggest red 

 drum dispersal and gene flow 

 among contiguous bays and estuar- 

 ies could be extensive. These in- 

 clude 1) transport of eggs, larvae, 

 or juveniles from spawning locali- 

 ties near the mouths of bays or es- 



tuaries to adjacent bays or estuar- 

 ies by oceanic currents (Lyczkoski- 

 Schultz et al., 1988 3 ), 2) movement 

 of sexually-mature adults from bay 

 or estuarine juvenile nurseries into 

 deeper, offshore waters prior to 

 spawning (Matlock, 1984), and 3) 

 formation of large, offshore schools 

 that can migrate extensively 

 (Overstreet, 1983; Matlock, 1984; 

 Swingle et al., 1984 1 ). 



In this study, data on allozyme 

 and mitochondrial (mt)DNA varia- 

 tion among red drum sampled from 

 Mosquito Lagoon on the east coast 

 of Florida are presented and com- 

 pared to data from previous stud- 

 ies. The goal of the study was to 



* Contribution No. 24 of the Center for Bio- 

 systematics and Biodiversity, Texas A&M 

 University. 



1 Swingle, W., T. Leary, D. Davis, V. Blomo, 

 W. Tatum, M. Murphy, R. Taylor, G. 

 Adkins, T Mcllwain, and G. Matlock. 

 1984. Fishery profile of red drum. Gulf of 

 Mexico Fish. Mngmt. Council and Gulf 

 States Mar. Fish. Comm., Lincoln Cntr, 

 Suite 331, 5401 West Kennedy Blvd., 

 Tampa, FL. 



2 Goodyear, C. P. 1989. Status of red drum 

 stocks of the Gulf of Mexico: report for 

 1989. Contrib. CRD 88/89-14, Southeast 

 Fish. Cntr, Miami Lab., Coast. Res. Div., 

 75 Virginia Beach Drive, Miami, FL. 



■' Lyczkowski-Schultz, J., J. P. Steen Jr., 

 and B. H. Comyns. 1988. Early life history 

 of red drum (Sciaenops ocellatus) in the 

 northcentral Gulf of Mexico. Mississippi- 

 Alabama Sea Grant Consortium (Project 

 No. R/LR-12). Gulf Coast Res. Lab., P.O. 

 Box 7000, Ocean Springs, unpubl. ms. 



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