The alternate-year occurrence of certain size groups also 

 takes place in the western Pacific (fig. 14) and it is enlightening to 

 compare the modes of bigeye tuna fronn the two regions, Kannimura 

 and Honma (1953) and Nakamura et al. (1953) report a "biennial" 

 occurrence of dominant size groups taken in the Japanese North Pacific 

 bigeye fishery. (The sizes of their fish are given in centimeters and 

 were converted to pounds by the Hawaiian length-weight formula. ) 

 Nakamura et al. report the modes for November 1948 to March 1949 

 (1948 season) and for October 1949 to April 1950 (1949 season) (see 

 table 3). Kamimura and Honma list the ranges for all modal groups 

 through the 1952 season and have included the data of Nakamura et al. 



OJ 0|J DJ DIJ aj 0|J D|J DU 



^— 1948 - I • 1949 • I ■ 1950 • I ■ 1951 - | • 1952 - | - 1953 ■ | ■ 1954— -| 



Figure 13. --"Growth lines" of Hawaiian bigeye tuna as 

 determined by modal values, based on the locations 

 of modes in figures 5-11. 



Where the Japanese investigators have not indicated modes, 

 they have been selected from their data. Thus modes are available 

 for each of five fishing seasons (1948-1952) (table 3). These modes, 

 plotted as fishing season midpoints on figure 15, together with the 

 growth lines from the Hawaiian fishery (fig, 13), show that modes in 

 the Japanese fishery alternate with those of the Hawaiian fishery 

 within a year, and that the slopes of the "growth lines" for both areas 

 are very similar,— The similarities in the slopes of the growth lines 

 and the presence of complementary cycles of approximately 2 years 

 suggest that the same bigeye population contributes to both fisheries. 



4/ 



— The modes in the Japanese landings have been connected by 



the present author. 



18 



