Frank Hetard 



Bureau of Commercial Fisheries 



Miami, FL 331^9 



The major research effort at the Tropical Atlantic Biological Laboratory 

 is the study of tuna distribution in the Tropical Atlantic Ocean and to 

 determine how their distribution is affected by the physical and biological 

 features of the ocean. During a recent cruise to west African waters 

 (September-December, 1968), an attempt was made to use satellite derived 

 APT data and ship-borne infra-red sea surface temperature data to supplement 

 routine oceanographic observations in the location of the Gabon-Angola oceanic 

 front. This front, represented by the 24°C sea surface isotherm, undergoes 

 a seasonalnorth-south migration and has been reported to affect the aggrega- 

 tion of tunas. 



The front was located and its migration followed during the cruise by 

 monitoring changes in the location of the 24°C sea surface isotherm 

 as determined by thermometer and by infra-red sensors aboard ship. 

 One-hundred twenty-three (123) Essa 6 APT transmissions were received and 

 photographed aboard ship and an attempt was made to relate the distribution 

 of the Gabon-Angola front to features revealed on these photographs. 



We were unable to use the satellite photos to locate the Gabon-Angola 

 oceanic front, probably because the temperature gradient associated with 

 the front was not strong enough to affect cloud formation. In areas of 

 upwelling where a strong temperature occurred, the photos 

 showed that there was an effect on cloud distribution. 



In the future we will continue in our effort to monitor from aircraft 

 and from satellite both physical and biological oceanographic conditions 

 by means of remote sensing techniques. Of particular interest is the 

 sea surface temperature, distribution of currents, distribution of fresh 



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