coincide with the summer cold advection period 

 and that the duration of the peak fishing is related 

 to the length of the summer cold advection period. 



The excellent relations between environ- 

 mental factors and the availability of skipjack 

 indicate that changes in the magnitude of Hawai- 

 ian stocks due to changing magnitudes of year 

 class or fishing pressure may not be of major 

 importance. They indicate that, in addition to 

 a favorable type of water, favorable dynamic 

 conditions are necessary for a good fishing sea- 

 son. Since fishing success seems to be associa- 

 ted with the dynamics of the system, it is not 

 surprising that an index reflecting environmental 

 processes (initial heating at Koko Head) has 

 proved to be of predictive value. 



Sprague, Lucian M. , and Leslie I. Nakashima 



A comparative study of the erythrocyte 

 antigens of certain tuna species. /Con- 

 ference Paper III - 8_/ 



The C-system of the skipjack ( Katsu - 

 wonus pelamis) was recognized by the action of 

 bovine normal serum containing natural anti-C 

 fractions on the cells of C-positive ski pjack 

 (Cushing, 1956).!/ 



C-like blood factors also occur o n the 

 erythrocytes of albacore (Germo alalunga), big- 

 eye (Parathunnus sibi),and yellowfin (Neothun - 

 nus macropterus). To date, absorption results 

 have not revealed C-system antibodies which 

 will differentiate subtyping relations between 

 the species, although such relations probably 

 exist. The relative frequency of occurrence of 

 C-positive individuals is quite different among 

 the members of the species tested. Albacore 

 (120) were 94 percent, bigeye (113) were 77 per- 

 cent, and yellowfin (37) were 98 percent positive 

 with standard C reagents. 



The A-system of the skipjack is recog - 

 nized by specific agglutinates formed in extracts 

 of the seeds of Glycine max (soy). A-positive 

 bloods are also commonly found in the bigeye 

 and albacore tunas, but to date they have not been 

 recognized in the few yellowfin tested. Several 

 other inter specific serological relationships are 

 also under investigation. 



Suzuki (1961)2/ has reported his find- 

 ings with regard to the serological cross 

 reactions of these species. At the present time 

 it is not known whether or not the relationships 

 described here fall within those described by 

 Suzuki. 



Sprague, Lucian M. , and Leslie I. Nakashima 



Studies on the erythrocyte antigens of 

 the skipjack tuna ( Katsuwonus 

 pelamis ). /Conference Paper III - 9. 7 

 ( See also abstracts of Symposium 

 Papers, Tenth Pacific Science Con- 

 gress. Symposium on immunogenetic 

 concepts in marine population 

 research, p. 186. ) 



At least five blood factors, which form 

 four systems of blood groups, have been identi- 

 fied on the red blood cells of the skipjack tuna. 



One, the C antigen, has been described 

 by Cushing (1956). _' C-positive individuals are 

 recognized by the action of natural bovine and 

 ovine heteroagglutinins. 



Four additional blood factors are now 

 recognized by the use of saline extracts of legume 

 seeds. Extracts of Glycine max detect A-positive 

 bloods, extracts of Phaseolus vulgaris detect 

 D-positive bloods, and extracts of Virgilia di- 

 varicata and Caragana arborescens detect two 

 blood factors in the B system, Be and Bf. The 

 relationships of Be and Bf are not well under- 

 stood except that they are mutually exclusive 

 properties, Be-positive animals being Bf- 

 negative and vice versa. About 20- 30 percent 

 of the skipjack tested are Be -Bf-negative. 



Of these reagents, those recognizing D- 

 positive individuals and those recognizing Bf- 

 positive individuals are not sufficiently definitive 

 for use in population studies. 



R eagents detecting C -positive, A- 

 positive, and Be-positive animals, however, 

 may be used to explicitly categorize skipjack 

 erythrocytes. These reagents have been used 

 in tests of 688 skipjack from the island or island 

 systems of Hawaii, Johnston, Christmas, Mar- 

 quesas, and Rangiroa (Tuamotu). 



4/ Cushing, John E. 1956. Observations 



on serology of tuna. U. S. Fish and Wildlife 

 Service Special Scientific Report: Fisheries 

 No. 183, 14 p. 



5/ Suzuki, Akimi. 1961. Serological studies 

 of the races of tuna - V. The blood groups of 

 yellowfin tuna. Report of Nankai Regional Fish- 

 eries Research Laboratory No. 13, p. 53-67. 



6/ See footnote 4. 



