USE OF PLANT EXTRACTS IN SEROLOGICAL 



STUDIES OF FISH 



by 



Fred M. Utter, George J. Ridgway, and 



Harold O. Hodgins, Chemists 



Bureau of Commercial Fisheries Biological Laboratory 



U.S. Fish and Wildlife Service 



Seattle, Washington 



ABSTRACT 



Seed and bark extracts representing 71 legume species were tested serologically 

 against numerous individuals of the genus Oncorhynchus and a limited number of 

 individuals from a broad taxonomic range of fish species. Many of these extracts 

 demonstrated distinct individual variations in certain fish species. The possibility 

 of distinguishing closely related fish species and their hybrids with some of the 

 extracts was demonstrated. Red blood cells must be fresh when these extracts are 

 used with Oncorhynchus species because marked alterations of reactions in this 

 genus were found with aged red blood cells. 



Eight of the extracts precipitated components of fish sera. Reaction of Chinook 

 salmon serum with Roblnia pseudoacacia bark extract demonstrated significant vari- 

 ability in reactive frequency when tested against groups of individuals from 

 Washington and Alaska. 



INTRODUCTION 



Identification of subpopulations or races 

 within a species of fish is a problem of vital 

 interest in fisheries management. The expense 

 and physical impairment involved with tagging 

 and marking programs have led to a search 

 for natural characteristics which, if con- 

 veniently detectable, could be valuable in 

 studying such populations. 



One type of character that is being widely 

 applied is the intraspecific variability of 

 erythrocyte antigens or blood types. Whenever 

 studied, the specificity of antigens has been 

 found to be genetically controlled, thus making 

 blood types highly useful as population markers 

 within a species. Extensive studies of blood 

 types in higher vertebrates have been made, 

 especially concerning humans, cattle, and 



chickens. These studies were successful and 

 stimulated research on erythrocyte variability 

 in fish. Results of this research showed 

 serological differences in sockeye salmon 

 populations (Ridgway, Gushing, and Durall, 

 1958), identified two herring populations off 

 Maine (Sindermann and Mairs, 1959), and de- 

 tected individual differences in erythrocyte 

 antigens of four species of Pacific salmon 

 (Ridgway and Klontz, 1960). 



Immune and natural antibodies of man and 

 other animals are the chief sources of blood 

 typing reagents. Although it has been known 

 for over 60 years that plant extracts will 

 agglutinate red blood cells of certain verte- 

 brates, the fact that they would detect individual 

 differences was discovered and utilized only 

 in the past 15 years (Renkonen, 1948; Boyd 

 and Reguera, 1949). Extracts of the seeds of 



