Figure 9 . Yellowfin tuna catch/ 100 hooks (January- 

 June ). This chart is based on JOHN R. MANNING cruise 11 and 

 CHARLES H. GILBERT cruise 1 (see table 4). 



Figure 10. Relative abundance of yellowfin tuna in the 

 western equatorial Pacific. Catches of the nine Japanese mother- 

 ship tuna fishing expeditions from June 1950 to October 1951 were 

 summarized by catching area. The weighted mean number of yel- 

 lowfin caught per hundred hooks fished was computed for each rec- 

 tangle of 1° of latitude by 5° of longitude as the basis for drawing 

 the contour lines of figure 11. 



Figure 11. Seasonal fluctuations in the longline catch 

 rate in the western Pacific, Each bar represents the weighted 

 mean number of yellowfin tuna caught per hundred hooks fished 

 between latitude 1°N. and 5°N. by all boats of the nine Japanese 

 mothership tuna fishing expeditions from June 1950 to October 1951, 



Figure 12. Comparison of catch rates from Japanese 

 commercial and POFI experimental fishing. There are included 

 in this graph the results of Japanese commercial fishing for 21 

 days at the several latitudes along longitude 170°W. during the 

 period October 27 to November 23, 1952, and the results of 10 

 days' fishing by the JOHN R. MANNING along the same longitude 

 during the period November 19-28, 1952. The Japanese fished 

 with 390 baskets per day, on the average, whereas the MANNING 

 set only 40 baskets per day. 



Figure 13. Abundance of yellowfin at 150° W. longi - 

 tude on successive cruises. This graph is based on HUGH M. SMITH 

 cruise 11. JOHN R. MANNING cruises 11. 12, 13. and the CAVA- 

 LIERI cruise. The catches are the average of the four adjacent 

 stations with the highest catch rate along the given longitude. Thus 

 they represent the richest 24C-mile-wide band regardless of the 

 latitudinal shifts in this band. 



Figure 14. Tuna spawning near the Equator . The 

 determinations were made by Fred C. June by measuring the dia- 

 meter of ova in the gonad and classifying the degree of maturity 

 according to criteria given in Fred C. June, 1953. 



42 



