LIST OF ILLUSTRATIONS 



Figure No. ^^8' 



Fronti8piece--Japane8e fishermen making leaders aboard the Settau Maru, the 

 6th expedition mothership, 



1. Western equatorial Pacific. The dotted-stippled border shows the 

 authorized area for tuna mothership expeditions. The solid black line 

 around the Marianas, Marshall, and Caroline islands shows the 



U. S. Trust Territory of the Pacific islands. After Shimada (1951a)... . 2 



o o 



2. Yellowfin tuna catch per 100 hooks by months for 1 -5 N. latitude, 



160 -165 E. longitude. Points obtained from table 4 8 



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3. Yellowfin tuna catch per 100 hooks by months for 1 -5 N. latitude. 



155 -160 E. longitude. Points obtained from table 4 9 



° o 



4. Yellowfin tuna catches per 100 hooks by months for 1 -5 N. latitude, 



135°-170°E. longitude. Points obtained from table 4 by averaging 



the unweighted nnean catch rates, excluding those baaed on less than 



3 days 9 



o o 



5. Bigeye tuna catches per 100 hooks by months, 1 - 5 N. latitude, 



135°-170°E. longitude. Points obtained from table 4 by averaging the 



unweighted mean catch rates, excluding those based on less than 



3 days 10 



6. Black marlin catches per 100 hooks by months, 1 -5 N. latitude, 

 135°-170°E. longitude. Points obtained from table 4 by averaging the 

 unweighted mean catch rates, excluding those based on less than 



3 days 10 



7. Latitudinal variation in the catch rates of yellowfin tuna, bigeye tuna, 



and black marlin by months auid years 12 



8. Catch rate of yellowfin tuna plotted against catch rate of bigeye tuna 



for each 1 of latitude by 5 of longitude block for all available data. 13 



9. Yellowfin catch rate plotted against bigeye catch rate for stations 



fished at 6°-7°N.. 178°-179°E. in October 1951 13 



10. Length frequencies of the four species of tuna commonly taken during 

 the mothership operations. For convenience a pound scale is provided 

 above each polygon 15 



11. Location of the major currents in the nnothership area of operation 



(after Schott 1935) 23 



12. Three temperature sections based on Japanese hydrographic stations. 

 Data furnished by U. S. Navy Hydrographic Office cruise reference 

 numbers 90015 and 90019. Isotherms are in centigrade 26 



