36 



COMMERCIAL FISHERIES REVIEW 



Vol. 28, No. 10 



Oceanography 



INDIAN OCEAN GIVES UP SOME SECRETS 



The Indian Ocean has the hottest, saltiest 

 water of any sea, the coldest surface water 

 in the Tropics, and the fastest midsea cur- 

 rent, report the scientists working with the 

 International Indian Ocean Expedition. 



Fig. 1 - Dr. Herman A. Fehlmann of the Smithsonian Institution, 

 Washington, D, C, sorts sea snakes brought aboard by trawl 

 during cruise in thie Arabian Sea, 



Fig. 2 - Two scientists from India, working guests, remove a sea 

 floor sediment sample from a LaFond-Dietz bottom snapper. 



From September 1959 to December 1965, 

 25 oceanographers from 15 nations explored 

 the Indian Ocean using every tool at their 

 disposal- -modern research vessels, weather 

 satellites, tramp streamers and large array 



of electronic gear --and gathered an unusual 

 amount of striking information. 



An Indian Ocean Meteorological Center 

 was set up in Bombay with United Nations aid. 

 Now the only international collection of small 

 marine animals or zooplankton is at the In- 

 dian Ocean Biological Center at Cochin. 



Fig, 3 - Sea floor sediment samples are removed from dredge and 

 put in glass jars for analysis. 



Some Exploration Findings: 



The existence of the Somali Current- -a 

 "western boundary current" running north 

 past Africa and Arabia at speeds up to seven 

 knots --was confirmed. (The Gulf Stream in 

 the Atlantic and the Kuroshio in the Pacific 

 travel at a maximum of four knots.) The 

 Somali is the only boundary current to cross 

 the equator and the only one that reverses 

 itself with the seasons. Only surface deep, 

 it races north during the summer when In- 

 dia's southwest monsoons are raging. When 

 the monsoons die out, it reverses its path 

 and heads gently south. 



Near the Arabian coast, where the Current 

 turns, the water's surface temperature drops 

 to 55° F, because of the tremendous upwell- 

 ing of cold water far below. This upwelling 

 contains nutrients from the depths. The con- 

 centration of nutrients in the western Arabian 

 Sea is twice as high as that in the North At- 

 lantic. The expedition's biologists were sur- 

 prised to see zooplankton actually clog the 

 nets they lowered during this period. 



However, at depths of more than 200 me- 

 ters, the Indian Ocean is oxygen-deficient. 

 When the cold upwelling water is brought clos - 

 er to the surface, fish are unable to survive. 



