as regards the construction of fishing gear, it is thought that this sea area will be an excellent 

 tuna longlining ground. It has already been noted that from the standpoint of weather it offers 

 superior conditions. 



3. Sulu Sea 



This body of water adjoins the Celebes Sea to the northward beyond the Sulu 

 archipelago and is surrounded by Borneo, Palawan, Mindanao, and others of the Philippine 

 Islands. To the northward it connects with the South China Sea beyond the island of Palawan. 

 During the season of southwesterly winds a rather strong current, which flows northward from 

 the Celebes Sea through this sea area into the South China Sea, appears somewhat east of the 

 middle of this area. It is said that on the western side near Borneo, there is a very weak cur- 

 rent flowing southward. 



There are no data at all for this season so nothing can be said concerning the water 

 temperatures ajid other hydrographic conditions, but it is assumed that they are not greatly 

 different from those of the Celebes Sea region. During the season of northeasterly winds on the 

 whole no very conspicuous currents can be seen in this area although there is a weak current 

 around the center of the area trending southwest. It is said also that taking the area as a whole 

 there is a weak circular current flowing in a counter-clockwise direction. 



Water temperatures and other conditions during the northeasterlies are in outline as 



o o 



follows. Around October surface temperatures are 28 C. to 29 C. , temperatures at the 50- 

 meter level differ little from the surface, while the 100-meter level shows temperatures of 

 24 C. to 26 C. Water colors mostly of I to II on Forel's scale have been observed, and the 

 transparency is high, figures of 30 meters or more being attained. Around February and March 

 the water temperatures are n-iarkedly lower, with figures of 26 C. to 26. 5 C. in the surface 

 layer, about 26 C. at the 50-meter level, and 20 C. to 22 C. at 100 meters. At about this 

 time a conspicuous zone of cold water appears centered on the line of 120 E. longitude about the 

 middle of this sea area. This water mass shows temperatures about 2 lower than the surround- 

 ing waters. At the saune time the water color changes greatly. III to IV on Forel's scale being 

 reported in the majority of cases. Consequently, the transparency is greatly lowered, with 

 values of 20 meters or less reported in most cases. 



During the season of southwesterlies the sea is always calm and operations would be 

 extremely easy. At the season when the northeast winds are strongest the area is visited from 

 time to time by high winds and high seas matking it difficult occasionally for small fishing 

 vessels to operate. 



This area has been for a good many years within the operating radius of fishing boats 

 based at Takao. Fishing operations have also been carried on here by boats of the Borneo 

 Fisheries Company based at Shamil, as mentioned in the section on the Celebes Sea, and boats 

 of the Sea Food Corporation based at Zamboanga. Boats from Takao for the most part fish this 

 region from September to the middle of October, taking principally yellowfin along with black 

 mcirlin, white marlin, and striped marlin. It appears that a fairly considerable catch of broad- 

 bill is also nnade at this season. Ordinarily once this season is passed there are almost no fish- 

 ing boats operating in this area, most of thenn appearing to turn to operations in the South China 

 Sea. As will be explained in a later section on the South China Sea, the main fishing season in 

 that area is the season of northeasterly winds from October on. The normal situation in most 

 years is for fishing to be most active in the early part of the season in the waters adjoining 

 the Sulu Sea. 



When we put together the facts that fishing is at its nnost active in the Celebes Sea 

 from July to September, that the greatest number of fishing vessels operate in the Sulu Sea in 

 September and October, and that in the South China Sea adjoining to the north fishing begins from 

 October on, beginning in the areas adjacent to the Sulu Sea, it may be thought that in this con- 

 nected series of sea areas the schools move gradually from south to north. However, if we leave 



58 



