A CONTRIBUTION TO THE OCEANOGRAPHY OF THE 

 SULU SEA(i) 



B}- Herbert W. Graham(-) 



Introduction 



The Sulu Sea is a " basin " sea surrounded by the Philippine Islands 

 and Borneo located between latitudes 5° N. and 12° N. ; longitude 

 117° E. and 123° E. It is separated from the South China Sea to the 

 west by the elongated Island of Palawan, from the Pacific Ocean to the 

 east by the southern Philippine Islands, and from the Celebes Sea to 

 the south by the Sulu Archipelago, 



The Sulu Sea- has been visited by a number of oceanographic expedi- 

 tions, but until the present investigations has never been subjected to 

 intensive study. The "Challenger " occupied two stations in the eastern 

 part of the sea. One " Dana " station was located in the south-east 

 portion. One " Snellius " station was included in the Sulu Sea in the 

 south central portion. The " Rambler " occupied one station in the 

 north-east while the " Penguin " occupied two stations in the eastern 

 part. The " Nassau " and " Albatross " also made temperature obser- 

 vations. Only seven stations with serial temperature observations have 

 been- made in the Sulu Sea until the present investigations. Bathy- 

 thermograph records have been taken in the extreme north-eastern 

 strip of the sea (Leipper and Wood, 1947). Japanese data on Philippine 

 waters recently made available include no stations in the Sulu Sea. 

 Data on the distribution of salinity in the Sulu Sea are very meagre, 

 while information regarding specific chemical substances is even more 

 scanty. 



The present report is based on investigations of the Philippine 

 Fishery Programme of the United States Fish and Wildlife Service. 

 As part of this agency's study of Philippine waters an intensive study 

 was made of the Sulu Sea in order to obtain information basic to the 

 investigation of the fishery resources of the Philippine region. 



The Sulu Sea was surveyed once during the north-east monsoon and 

 again during the south-west monsoon b}' four cruises of the " Spencer 

 F. Baird." Each survey was made by occupying a grid of stations 

 spaced 60 miles apart. The first survey during the north-east monsoon 

 was conducted on two cruises — one from 7th to lith October, 1947, 

 the second from 3rd to 11th December, 1947. The survey during the 

 south-west monsoon included two cruises, also — one from 15th to 25th 

 June, 1948, the other from 10th to 16th July, 1948. Thirty-seven 

 stations were occupied during the first survey and forty-two during the 

 second survey, most of which were reoccupations of previous stations. 



Serial temperatures and water samples were taken from the surface 

 to 2,000 metres and at one station to 4,000 metres. In addition to 

 salinity, the water was analysed for dissolved oxygen, phosphate, silicate, 

 hydrogen-ion concentration and, in some cases, nitrate, nitrite, and 

 alkalinity. 



(^) Published with permission of the Director, United States Fish and Wild- 

 hfe Service. 



(2) On leave from Mills College, Oakland, California. 



225 



3 — Pac. Congress 



