PROTEIN TAXONOMY OF THE GULF OF MEXICO AND 

 ATLANTIC OCEAN SEATROUTS, GENUS CYNOSCION 



Michael P. Weinstein' and Ralph W. Yerger- 



ABSTRACT 



Taxonomic relationships among the western North Atlantic seatrouts, genus Cynoscion, were 

 investigated utilizing acrylamide gel electrophoresis. Several tissues (blood serum, eye lens, and 

 muscle) were incorporated in this study to gain a better taxonomic overview than would be attainable 

 with a single protein system. 



Blood serum exhibited considerable variation in banding patterns. Because direct interspecific 

 comparisons were not possible, a phenetic analysis was employed. Eye lens and muscle patterns, 

 however, were directly comparable. Based on the overall results, three taxonomic conclusions may be 

 drawn. First, with the exception of a single taxonomic distance (di^) value calculated in the phenetic 

 analysis, the relationships established by electrophoresis reflect the phyletic relationships proposed by 

 Ginsburg. This "aberrant" value is believed to result from the small sample size and the possibility of 

 ecological convergence. Second, the data indicate that Cynoscion nehulosus is the most divergent of the 

 four forms, supporting previous morphological and ecological conclusions. Third, as suggested by 

 previous studies, the taxonomic status of C. arenarius as a distinct species is again questioned. 

 Electrophoretic patterns indicate that it should be regarded as a subspecies of C. regaiis. 



Investigation of general protein systems has often 

 proven useful in elucidating taxonomic relation- 

 ships. Species-specific banding patterns have been 

 reported for numerous taxa including fishes 

 (Tsuyuki and Roberts 1965; Perrier et al. 1973). 

 Nyman and Westin (1969) studied serum patterns 

 of cottid fishes from the Baltic Sea and concluded 

 that the patterns reflected the commonly accepted 

 scheme. Species and group (genus, family, class) 

 specificities have also been described for eye lens 

 proteins of several fishes (Rabaey 1964, Bon et al. 

 1964, Cobb et al. 1968). Recently Eckroat (1974) 

 compared members of the pike family (Esocidae) 

 using this tissue. Myogens have proven par- 

 ticularly useful in reviews of several groups in the 

 families Catostomidae (Tsuyuki, Roberts, and 

 Vanstone 1965; Tsuyuki et al. 1967; Huntsman 

 1970), Salmonidae (Tsuyuki, Roberts, Vanstone, 

 and Markert 1965; Tsuyuki et al. 1966) and Scor- 

 paenidae (Tsuyuki et al. 1968; Johnson et al. 1972). 

 In this study we have investigated taxonomic 

 affinities among the western North Atantic sea- 

 trouts, genus Cynoscion. Four species are current- 

 ly recognized: spotted seatrout, C. nebulosus 

 (Cuvier); weakfish, C. regaiis (Bloch and 



'Lawler, Matusky & Skelly Engineers, 415 Route 303, Tappan, 

 NY 10983. 



^Department of Biological Science, Florida State University, 

 Tallahassee, FL 32306. 



Manuscript accepted March 1976. 



FISHERY BULLETIN: VOL. 74, NO. 3, 1976, 



Schneider); silver seatrout, C. nothus (Holbrook); 

 and sand seatrout, C. arenarius Ginsburg. Cynos- 

 cion arenarius is restricted to the Gulf of Mexico; 

 specimens have been captured from Campeche, 

 Mexico, eastward to the southwest coast of 

 Florida. Cynoscion regaiis has been generally 

 considered to be limited to the Atlantic coast. 

 Guest and Gunter (1958) described its southern- 

 most occurrence as the St. Lucie estuary, Fla. We 

 now have evidence which conclusively proves its 

 presence in the Gulf of Mexico. 



Cynoscion nehulosus occurs from New York to 

 Mexico (Bay of Campeche); its center of abun- 

 dance is in Florida and the Gulf States (Pearson 

 1929). Cynoscion nothus is found from Chesapeake 

 Bay, Md., to the Bay of Campeche but is uncom- 

 mon at the southern extremity of its range. It is 

 relatively abundant on the gulf coast and from the 

 east coast of Florida to North Carolina. 



Several tissues (blood serum, eye lens, and 

 muscle) were utilized in order to achieve a better 

 taxonomic overview. Since it is difficult (if not 

 impossible) to construct a phylogeny solely on the 

 basis of biochemical differences, our results have 

 been compared with the existing phylogenetic 

 schemes of Ginsburg (1929) who recognized C. 

 arenarius and C. regaiis as cognate species, and 

 Mohsin (1973) who placed C. arenarius and C. 

 nehulosus in one phyletic line, and C. regaiis and C 

 nothus in another. 



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