ABSTRACT 



Iiiflividual variations in erythrocyte antigens have been found in redfish, 

 Sebastcs mariniis, from the western North Atlantic. Two closely related 

 antigens, tentatively labeled Ai and A-, were demonstrated with specific 

 reagents created by absorptions of rabbit antisera. Each reagent would 

 agglutinate cells of only one antigenic type, so it was possible to identify 

 fish as possessing A, or A- antigen. Individuals with the erythrocyte antigen 

 Ai make up more than 75 percent of the Eastport (Maine) redfish population. 

 Since antigen frequencies may vary from one population to another, quantita- 

 tive studies of each major fishing area should provide further information 

 about discreteness of groups and the extent of their movements. 



