weather and logistic limitations made fishing 

 farther north impossible. Second, there was a 

 seasonal shift in the southern linnit Of the alba- 

 core catches, the winter limit being farther 

 south than the fall limit. The magnitude of this 

 shift was about equal to the movement of certain 

 surface isotherms, e.g., the 60 F. isotherm 

 located between 41 and 42 N. on 170 W. during 

 the fall moved south to between 32 and 33 N. 

 at the same longitude during the following winter 

 (fig. 2). 



There are a number of records of Japanese 

 commercial fishing in the general zone in which we 

 took albacore during the winter of 1953-54. These 

 are summarized in figure 3 and table 3. Most of 

 the Japanese effort was concentrated to the west 

 of 180 (fig. 3) whereas we surveyedthe areafrom 

 180 east to 150 W. (fig. 2). Japanese fishing was 

 confined to the zone lying between 28 and 35 N. 

 latitude. The best Japanese catches were made 

 during December and January, when a number of 

 areas showed catches of 5 or more albacore per 

 100 hooks. Longitudinally, their best area appears 



to have been immediately west of 180 longitude 

 (170°E. to 180°), however, from table 3 it is 

 apparent that significant catches were made as 

 far west as 141°E. during December 1953. In 

 POFI's fishing during January-March 1954 and 

 1955 at only one station was the albacore catch 

 rate as high as those of the good catches (> 5. 

 per 100 hooks) nnade by the Japanese to the west 

 (compare figs. 2 and 3). This does not mean 

 that the area immediately north of Hawaii is 

 less productive than the area to the west, since 

 only limited experimental fishing has been com- 

 pleted thus far, furnishing only a rough estimate 

 of albacore availability. It should be added here 

 that the catch rates of the POFI 13-hook gear 

 may not be strictly comparable with the catch 

 rates of the Japanese 6-hook gear. Although 

 the relative efficiency of the two types of gear 

 in taking albacore has not yet been determined, 

 it has been shown for the central equatorial 

 Pacific yellowfin tuna that 11-hook gear is less 

 efficient in terms of catch per 100 hooks than 

 6-hook gear (Shomura cind Murphy 1955). 



35° 



30° 



25° 



30° 



25° 



160° 



I70°E 



180° 



170°W 



160° 



150° 



Figure 3. --Summary of some Japanese longline albacore catches (data from 

 individucil vessel reports transmitted to POFI by Mr. Toshizo Nomura). 



