In Slimmer 1964, Kazuo Fujino. internationally known for 

 his studies of the genetics of whales, joined the staff of the 

 Laboratory in Honolulu to head the work on subpopulations. 

 The discovery by Fujino and his colleagues of a highly 

 sensitive new blood group system for distinguishing sub- 

 populations of the commercially important skipjack tuna 

 has highlighted recent blood group research at our Labora- 

 tory. This new system is called the Y blood group system. 

 (As with most blood group designations, the name is arbi- 

 trary). What the Y system offers is an opportunity to 

 examine any sizeable portion (100 or more fish) of the 

 skipjack population and determine mathematically whether 

 it represents a single subpopulatiun. It supplements earlier 

 systems and. in recognizing several more and e.xtremely 

 subtle differences in blood types than the others, holds forth 

 the promise of differentiating subpopulations that are closely 

 related. To date, tests of the Y system have shown the 

 existence of 15 kinds of "Y" individuals among skipjack. 



It is the proportion of each of these kinds of "Y" types 

 in a sample that allows scientists to delineate subpopula- 

 tions. A single system is often not adequate, hence the 

 merit of several. The Y system of skipjack blood will thus 

 not replace the B and other systems already used but sup- 

 plement and extend them. 



The geneticist drawing his samples from the commercial 

 fisheries can distinguish subpopulations, but he cannot deter- 



mine the place of their origin. To do that, he must have 

 samples from far afield. For this reason, our Laboratory 

 has collected samples of tuna bloods from throughout the 

 Pacific. 



The blood group studies represent the apijlication to 

 fishery problems of principles and techniques pioneered in 

 other fields. Another technique of genetic research on 

 human beings that has recently come into use in fishery 

 work is the study of the sera of fish bloods. Certain inherited 

 components of the clear fluid of bloods can be distinguished 

 by a method called starch gel electrophoresis, which relies 

 on the diflferential response of certain proteins in the serum 

 to an electric current. Fujino and his associates have used 

 this technique to locate two types of proteins in the sera 

 of both skipjack and yellowfin tunas. They have found three 

 phenotypes that allow the rigorous mathematical analysis 

 upon which conclusions concerning subpopulations are based. 

 An additional, very rare phenotype has been observed in 

 the skipjack tuna. 



Research on subpopulations deals with fish in units of .r 

 thousands to .r millions These units in their totality con- 

 stitute a species. And it is with the concept of species that 

 both fishermen and fishery scientists are most familiar. At 

 our Laboratory, two species are of special interest, the 

 skipjack and the albacore tunas, both of which form the 

 basis of large U. S. fisheries in the Pacific. 



THE FISHERIES 



The Catch of Tunas 



Two hundred sixteen countries have commercial fisheries, 

 but pickings are small for many of them. In 1963, the most 

 recent year for which reliable statistics are available, two 

 I'acific nations, Japan and Peru, took almost one-third of 

 the world's 51.1 million ton harvest of the sea, according 

 to FAO. 



By weight, the tunas (or FAO's "tunas, bonitos, and 

 skipjacks") do not bulk large in the world catch, accounting 

 for only 3 percent of the total, or 1.4 million tons out of 51.1. 

 They are among the most highly prized of fishes, so that in 

 value to the fishermen they overshadow many others caught 

 in greater quantities. In California in 1964, the four main 

 species — albacore, bluefin, skipjack, and yellowfin — com- 



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