However, judging by the activities of commercial fishing vessels, fishing for striped marlin and 

 black marlin is rather good in the northern Marianas from this period to around March or April. 

 And it appears that quite a few medium-sized vessels have operated at this season in this area 

 and somewhat to the eastward, 



o 



The Ogasawara Islands area to the north and the western Pacific north of 25 N. 



latitude have been gradually subjected to exploitation over a long period of years, but because of 

 the sudden development of the fishing grounds of the southern part of the former South Seas 

 Majidate, the fishermen skipped over the area presently under discussion and went directly to fish 

 in the vicinity of the Equator. As a result the fishing grounds of this region have been left with 

 hardly any attention paid to them and their significance and value as fishing grounds have been 

 left almost completely unknown, 



8. East Philippines Sea (0° to 30° N.. 120 to 130° E.) 



The area between and 20 N. at 120 to 130 E. , excluding those waters belonging 

 to the Celebes Sea, Sulu Sea, and South China Sea, will be described as the East Philippines Sea. 



That part of the Jirea north of 5 N. latitude outside the coastal zone of the Philippine 

 Islands is the so-called Philippine Trench, which is extremely deep and without any reefs or 

 shoals on the bottonn. South of 5 N, latitude there are scattered snnall islands and both the 

 topography and the oceanographic conditions are complex. 



During the season of southwest winds the part of this region between 10 and 15 N. 

 latitude lies within the North Equatorial Current. Because of the impingement of this westward 

 flowing current upon the Philippine Islands, the currents in waters adjacent to the Islands are 

 quite complex. North of 15 N. latitude the currents flow generally north or northwest, forming 

 the origin of the Kuroshio (Japan Current). South of 10 N. the currents turn south or south- 

 eastward, part of them entering the Celebes Sea and the rest flowing into the Equatorial Counter- 

 current together with the current which flows north to the Molucca Strait. 



North of the central portion of the area the water temperatures are generally high, 

 with temperatures from May to September of 28 C. to 29 C. at the surface, about 28 C. at 50 

 meters, and about 27 C. at 100 meters. In the southern portion the vertical distribution of 

 water temperatures is remarkably complex, with occasional temperatures of about 20 C, re- 

 ported for the 100-meter level. This condition is particularly marked in those areas adjacent to 

 the Molucca Strait, and it appears that in many cases there are two to three marked thermoclines 

 between the surface and about 200 meters. In most cases water color of I to II on Forel's scale 

 and high transparencies of 30 to 40 meters have been recorded. 



During the season in which northeasterly winds prevail the principal currents do not 

 differ greatly from the pattern which they exhibit during the season of southwesterlies, but the 

 current which flowed north through the Molucca Strait disappears and a current appears flowing 

 in the opposite direction southweird through that Strait. The boundary between the Equatorial 

 Countercurrent and the North Equatorial Current is pushed somewhat southward from its position 

 during the season of prevailing southwesterly winds. 



Little is known of the distribution of water temperatures because of the paucity of the 

 data, but compared to the season of southwesterlies temperatures in the northern part appear to 

 be lowered by 2 - 3 C. at the surface, and 1 - 2 at 50 jind 100 meters. In the southern por- 

 tion the temperatures appear to be lowered by 1 - 2 C. at all levels. There is no great differ- 

 ence frona the season of southwesterlies in water color zuid tr sinsparency. 



During the season of southwesterly winds the surface is generally extremely calm. 

 However, during the typhoon season the northern part of this sea area is frequently crossed by 

 these storms and operating during this season requires considerable caution. During the north- 

 easterlies operations are not infrequently hampered by high waves and seas, 



73 



