COMPARATIVE STUDY OF POPULATIONS OF THE 

 STRIPED BASSi/ 



This stady was instituted to determine 

 whether gill rakers were a valid taxonomic tool 

 that could be used along with other meristic 

 characters to classify populations of striped 

 bass, Roccus saxatilis (Walbaum). Racial 

 studies of the striped bass have been made by 

 Merriman (1937 and 1941), Vladykov and Wal- 

 lace (1952), Raney and de Sylva (1953), Raney, 

 Woolcott, and Mehring (1954), Raney and Wool - 

 cott (1955), and Raney (ms.). 



The striped bass is found along the At- 

 lantic coast from the St. Lawrence River to the 

 northern part of Florida. It also occurs in the 

 Gulf of Mexico from the west coast of Florida 

 to Louisiana. Striped bass from northern New 

 Jersey were shipped to California in 1879 and 

 1881 and are now well established there. 



The striped bass is economically im- 

 portant in most parts of its range. It is there- 

 fore necessary, as an aid to management of 

 this species, to know where populations occur 

 and how to separate them from other populations 

 that exist in close proximity. This gill-raker 

 study was conducted, along with many other past 

 and present racial studies, to help achieve this 

 end. 



The writer wishes to express his appre- 

 ciation to Dr. Edward C. Raney of the Depart- 

 ment of Conservation for his guidance during 

 the course of this study. He also wishes to 

 thank Dr . Clifford O . Berg of the Department of 

 Entomology and Limnology for his criticism of 

 the manuscript. Dr. R.G.D. Steel and Dr. 

 Douglas Robson gave valuable statistical advice. 



LITERATURE REVIEW 



Vladykov and Wallace (1952) working 

 with the striped bass from the Atlantic coast, 

 maintained that gill rakers were not a useful 

 character for racial determination because they 

 thought they varied with age . Other workers 

 have used gill-raker counts in taxonomic studies. 

 Vladykov and Beaulieu (1951), working with the 

 sturgeon in the Province of Quebec, found that 

 the young of Acipenser fu Ivescens have their 

 gill rakers closer together than the adults. This 

 is explained by the fact that the development of 

 the gill rakers is already completed in the case 

 of the young, while growth of the gill arch con- 

 tinues through the rest of the life of the fish. 

 TTiey worked with three species of Eastern North 

 American sturgeon and concluded that the number 

 of gill rakers on the first branchial arch is a 

 very important taxonomic character. 



SuSrdson (1952), studying coregonid 

 fishes in Sweden, considered that environment 

 affects the number of gill rakers very slightly 

 or not at all. Hildebrand and Schroeder (1928) 

 found that the number of gill rakers of Alosa 

 sapidiffiima change with age. Vladykov (1954) 

 thought that the number of gill rakers were of 

 very little value as a character for chars 

 (Salvelinus) . Working with the berycoid fish 

 family Polymixiidae, Lachner (1955), found that 

 the number of dorsal fin rays and the total num- 

 ber of gill rakers were the most critical char- 

 acters in the separation of the species. Ginsburg 

 (1955), in his study of the genus Bembrops, also 

 used gill rakers as an important meristic char- 

 acter. McGregor (1924) used a combination of 

 gill rakers, pyloric caeca, branchiostegals, ova, 

 and vertebrae to separate races of king salmon 

 from the Klamath and Sacramento Rivers in 

 California . 



Gill rakers have been used as a taxonom- 

 ic character at all levels of differentiation, 

 generic, specific, subspecific, and race . 



\l A thesis presented to the faculty of the 

 Graduate School of Cornell University for the 

 degree of Master of Science . 



McHug^'s (1951) study of the meristic 

 variations of Engraulis mordax mordax showed 

 a gradual increase in the number of gill rakers 

 in larger fish. He was able to demonstrate by 

 statistical treatment among three localities, that 

 ranged from British Columbia to Baja California, 

 that there were highly significant differences among 

 localities and between sexes within each locality . 



