In conjunction with the Pacific Oceanic Fishery Investigations' 

 study of the tuna resources of the central Pacific, the hydrography of 

 Hawaiian offshore waters was investigated during six oceanographic 

 survey cruises. The first three of these, Hugh M. Smi th cruises I, 

 10, and 12 of December 1949, July 1951, and October 1951, were ana- 

 lyzed and recorded by McGary (1955). This report covers the ren:iain- 

 ing cruises 17, 20, and 21 of the Hugh M. Smith , which took place 

 September 5 to September 15, 1952, February 25 to April 4, 1953, and 

 August 4 to August 26, 1953 respectively. On Hu gh M. Smith cruise 26, 

 May and June 1954, additional oceanographic data were obtained in con- 

 junction with skipjack scouting. These have not been analyzed in this 

 report but are tabulated in the appendix. 



The principal observations consisted of routine temperature . 



and salinity sampling together with 200-meter oblique plankton hauls.— 

 Reliable inorganic phosphate-phosphorus data were obtained on cruise 

 21. The hydrographic data were collected and processed by methods 

 described by Cromwell (1954), Stroup (1954), and McGary (1955). 



Each cruise is discussed separately using a similar outline for 

 each. A short sumnnary of the cruise report is given first to indicate 

 the nature of the observations. This is followed by a brief summary of 

 the weather conditions encountered during the cruise. 



The hydrographic data are then analyzed in two major groups, 

 first those fronn the surface layer and then those from the subsurface 

 layers. In the former the distributions of temperature, salinity, den- 

 sity, and surface geostrophic currents are emphasized. In the latter, 

 attention is focused on the subsurface distribution of nnass and how it 

 contributes to the surface currents. The results of these analyses are 

 then briefly summarized. 



The report is concluded with a general summary in which the 

 observations for each cruise are compared in order to point to possible 

 seasonal variations. The tabulated observations for each cruise are 

 included in the appendix. 



The discussion is generally based on figures in which the 

 variables are plotted cuid contoured on horizontal surfaces with points 

 of observation marked by dots. As is generally the case, contour lines 



— The plankton data for cruise 17 have been presented by King 

 and Hida (1954). Those for cruises 20 and 21 are in preparation for 

 separate publication. 



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