15 



lected 360 skipjack blood samples from off the coast of Baja 

 California, the analysis of which showed them to be indistin- 

 guishable from blood samples of one of the skipjack subpopu- 

 lations found at the same time in the Hawaiian fishery. Since 

 California Current Extension Water also is found off Baja Cal- 

 ifornia, this finding lends support to the hypothesis that skip- 

 jack subpopulations are uniquely associated with dynamic phys- 

 ical features of the major oceanic circulation systems. 



with tuna species have shown that this technique readily dif- 

 ferentiates between albacore, bigeye, bluefin, and yellowfin 

 tunas and appears also to differentiate between individuals 

 within a species. 



In 1963, biologists seeking to identify tuna subpopulations 

 had the opportunity to compare directly the reagents being 

 usedin their individual research programs. The need for this 

 had long been recognized. Dr. Lucian M. Sprague visited Dr. 

 Akimi Suzuki of the Nankai Regional Fisheries Research Lab- 

 oratory in Japan to make direct comparisons of reagents of 

 albacore tuna developed in the Biological Laboratory and those 

 developed by Dr. Suzuki. Results of the tests demonstrated 

 that some reagents developed by Dr. Suzuki were directly com- 

 parable with ours. Both research groups may expect to benefit 

 from the pooling of knowledge that resulted from these and 

 subsequent direct comparisons. 



Some progress has been made in the studies of blood- 

 group systems in yellowfin, albacore, and bluefin tunas, and 

 these studies will continue. The rate of progress will depend 

 to a large extent on the supply and quality of blood samples 

 obtainable. To date, yellowfin samples have been available 

 only during the summer and in limited numbers from the 

 Hawaiian longline fishermen. Albacore samples are only spo- 

 radically available, and often they have been frozen for several 

 months. 



Bluefin samples are available but so far have proved the 

 most difficult to work with; however, the new technique of 

 starch-gel zone electropheresis shows some promise tor this 

 species. In this technique, electric current separates the pro- 

 tein components, which occur naturally in the serum of animals, 

 into several well-defined chemical zones on a plate of potato 

 starch gel (fig. 17). Because the presence or absence of cer- 

 tain proteins within these zones can--by application of the 

 Hardy-Weinberg law--be demonstrated to be under genetic 

 control, this technique is a potentially valuable tool for dif- 

 ferentiating subpopulations. Tests of its adaptability to studies 



Figure 17. --Typical starch gel, showing hereditary 

 protein components in fish serum. 



