The foregoing table shows that in general the fishing is best between 5 and 10 N. , 

 followed by to 5 N. , with the catch rates falling off ae one goes north from 10 N. 



Black tuna were taken only between 15 and 20 N. In the case of the yellowfin, there 

 is a boundary in the vicinity of 10 N. , with the catch rates dropping off sharply to the northward. 

 South of 5 N. the catch rates are also somewhat lower than between 5 and 10 N. The spear- 

 fishes (chiefly black marlin) show their highest catch rates in the area between 10 and 15 N. 



o o o o 



Fishing is somewhat poorer between 5 N. and 10 N, and between 15 N. and 20 N. , but the 



difference is slight. In the area fronn to 5 N. the catch rates drop sharply as connpared with 

 the more northern areas, showing that there is a marked distributional boundary between 5 and 

 10 N. latitude. Bigeye tuna fishing is best between 5 and 10 N. , with catches being nnade only 

 rarely farther to the north. In general the fishing within this area is controlled by the catch of 

 yellowfin and spearfishes and, as the foregoing table shows, the yellowfin in the southern part and 

 the spearfishes in the northern part are the main species controlling the fishing situation. 



o 



The situation is not thoroughly known because of the scarcity of data, but between 



and 5 N. it appears that there are no marked fluctuations in the fishing throughout the year. 



It appears, however, that fishing is particularly active around March and from July to September. 



North of 5 the spearfish catch increases from May to August. 



o 



The investigations of the Shonan Maru cover almost the whole area north of 3 N. 



latitude from June to September. Based on these data, the catch rate curve from north to south 

 for this sea area is shown in figure 9. 



The variations in catch rate shown by the curve are rather large, but in general the 

 yellowfin catch rates are clearly higher in the south and drop off sharply to the north. The 



spearfishes on the contrary cire high in 

 the north and low in the south. It is 

 thought that the irregularity of these 

 curves is due to the small number of 

 fishing stations, and that if the number 

 of stations were increased the curves 

 would probably show more regular trends. 



15 



o 

 a: 



UJ 



a. 



o YELLOWFIN 

 ^ BLACK MARLIN 



S (LATITUDE SCALE MISSING) N 



Figure 9. --Catch rates by latitudes 

 (E. Philippines Sea) 



The range within which the 

 catch rate curves for the yellowfin and 

 spearfishes intersect appears to be 

 roughly from 10 to 1 5 N, Although 

 differences can be detected in the numer- 

 ical value of the catch rates, the situation 

 outlined above appears to be exactly simi- 

 lar to that presented by the waters of the 

 former South Sea Islands Mandate, which 

 adjoins this area on the eastward. 



If we attempt to connpare 

 these fishing conditions with oceanograph- 

 ic conditions, the area from 10 to 15 N. 

 is where the North Equatoriad Current 

 impinges upon the Philippine Islands. 

 Farther to the north the currents gener- 

 ally flow northward or northwestward and 

 make up the origins of the Kuroshio. 

 South of 10 N. the currents flow south or 



southeastward, corresponding in part to 

 the area of origin of the Equatorial Countercurrent. The rest flow into the Molucca Strait area. 

 Just as in the former South Sea Mandate farther to the east, yellowfin are abundant in the 

 Equatorial Countercurrent and the spearfishes are abundant in the North Equatorial Current. 



76 



