ABSTRACT 



This report describes the oceanographic methods used, and lists in tabular form the results 

 obtained, on Expedition SCOT in the eastern tropical Pacific. This expedition, conducted in 

 April, May and June, 1958, by the Scripps Institution of Oceanography with the co-operation 

 of the Inter-American Tropical Tima Commission, was the first of a series of cruises devoted 

 to the oceanography of the United States tropical tuna fishing region. These cruises are part 

 of a program of investigations carried out by the Scripps Institution under contract to the U. S. 

 Bureau of Commercial Fisheries. 



The main object of the expedition was to study the distribution of ocean properties in the 

 region as a whole at a different season and with greater coverage than in any former expedi- 

 tion. The survey extended from San Diego, California, to latitude 5°N. 



Properties measured or computed were: weather conditions, temperature, salinity, density, 

 thermosteric anomaly, dynamic height anomaly, dissolved oxygen concentration, inorganic 

 phosphorus concentration, the attenuation of diffuse submarine daylight, incident solar radia- 

 tion, clilorophyll a, standing crop of zooplankton, standing crop of small nekton, surface 

 current direction and velocity (by GEK), and primary production rate. Additional informa- 

 tion presented includes a summary listing of bathythermograph observations and of organisms 

 captured in night-lighting operations. Some preliminary results of analysis of data, including 

 experiments made aboard ship on the growth of ocean phytoplankton in response to various 

 combinations of added chemicals, are given. 



