Oceanic Conditions During the Joint Investigation of 



the Southeastern Tropical Atlantic (JISETA)— 



February, April, and September-December 1968 



STEVEN K. COOK, 1 JAMES F. HEBARD,' MERTON C. INGHAM,' 

 ELLSWORTH C. SMITH, 2 and CARLOS AFONSO DIAS 3 



ABSTRACT 



Oceanic conditions in the upper 1,000 meters in the water column off tropical western Africa are 

 portrayed. The portrayal is comprised of vertical sections of temperature, salinity, sigma-f, oxygen, and 

 phosphate A description of methods of sampling, analysis, data processing and quality control is 

 presented. 



INTRODUCTION 



The Joint Investigation ot the Southeastern Tropical 

 Atlantic (JISETA) was conceived in 1967 at the Tropi- 

 cal Atlantic Biological Laboratory (now Southeast 

 Fisheries Center) of the Bureau of Commercial 

 Fisheries (BCF), U.S. Department of Interior (now the 

 National Marine Fisheries Service, U.S. Department of 

 Commerce) in Miami, Fla. The investigation was plan- 

 ned as an extension of a broad study of the tropical 

 Atlantic tunas and their ecology. Of particular interest 

 to JISETA was the relationship between the distribu- 

 tion of surface-schooling tunas and seasonal changes 

 in their environment. Specific oceanic features along 

 the coast of western Africa between the equator and 

 17°S(Fig. 1) thought to influence tuna distribution were 

 fronts, upwelling areas, and the effluent plume of the 

 Congo River. 



It soon became apparent that the investigation of 

 this area was too much for one vessel, BCF's RV Un- 

 daunted, and assistance was requested from various 

 U.S. and foreign laboratories. Two organizations 

 agreed to participate, the Missao de Estudos 

 Bioceanologicos e de Pescas de Angola, with the RV 

 Goa, located in Lobito, Angola, and the U.S. Coast 

 Guard Oceanographic Unit, located in Washington, 

 DC, which agreed to send the USCGC Rockaway. 



'National Marine Fisheries Service, NOAA, Washington, DC 

 20235. 



2 National Oceanographic Data Center, NOAA, Washington, DC 

 20235 



3 Missao de Estudos Bioceanologicos e de Pescas de Angola, 

 caixa Postal 677, Lobito, Angola, PWA 



This report is a compilation of the physical and 

 chemical data collected by the three ships in the vari- 

 ous phases of JISETA, portrayed in a series of vertical 

 sections corresponding with transects of stations oc- 

 cupied during the investigation. The report is not in- 

 tended to be the sole publication resulting from 

 JISETA, but instead is intended to serve as a source of 

 physical and chemical data which should be utilized 

 in further research in fisheries ecology or oceanog- 

 raphy. Although biological data were collected during 

 JISETA also, there are no similar portrayals of these 

 data planned; they will be utilized in research papers 

 instead. 



STATION PATTERNS AND 

 CRUISE SCHEDULES 



The station patterns occupied during the various 

 phases of JISETA are shown in Figures 4, 30, 70, 96, 

 1 06, 1 37, 1 92, 256, 277, and 31 7. The cruises compris- 

 ing the investigation were conducted according to the 

 following schedules: 



Undaunted 6801: 



14-25 February — phase I (2-11 °S) 

 8-16 March —phase II (15-1 9°S) 

 15-21 April —phase III (2°S-5°N, 



Northeastern Gulf of Guinea) 



Undaunted 6802: 

 19-23 September- 

 15-29 October - 

 11-22 November - 



-phase I (1°N-6°S) 

 -phase II (6-1 2°S) 

 -phase III (12-1 7°S, 

 results not included) 



