and the young move rapidly to the upper estuary ; 

 adults rarely reenter the estuary. The young arrive 

 earlier and are more abundant in the winter of 

 years of liigh water temperatures in November and 

 December but maximum abundance, reached in 

 May or June, seems to be unrelated to water tem- 

 peratures. The volume of food in the stomachs 

 of croakers is greatest during the first few months 

 after their arrival in the upper estuary. While in 

 the estuary they feed primarily on animals; poly- 

 chaetes are the dominant food of all sizes of fish. 

 Mollusks, large crustaceans, and fish are eaten in 

 greater amounts as croakers become larger. As 

 croakers grow, the larger individuals move down 

 the estuary causing a stratification by size along 

 the salinity gradient. Migration to the Gulf and 

 gonadal development begin in the late summer 

 and fall. Ovaries of fish in their first year of life 

 contain about 40,000 eggs. 



ACKNOWLEDGMENTS 



Hughey L. Jones, Nelson R. Cooley, and Philip 

 A. Butler of this laboratory assisted me. 



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146 



U.S. FISH AND WILDLIFE SERVICE 



U.S. GOVERNMENT PRINTING OFFICE : 1969 0—361-679 



