MID-PACIFIC OCEANOGRAPHY - II 



Introduction 



This is the second in a series of reports planned to pre- 

 sent oceanographic data obtained by the Pacific Oceanic Fishery In- 

 vestigations of the U. S„ Fish and Wildlife Service „ The first 

 (Cromwell 1951) presented oceanographic data in tabular and graphical 

 form with discussions of some of the results of cruise 2 of the Hugh 

 M. Smith, the first equatorial cruise of the POFI program concerned 

 primarily with the collection of physical and chemical data Q This pre- 

 sent report is concerned with Smith cruises 5 and 8, the second and 

 third equatorial cruises with similar objectives „ 



The primary purpose of this report is to present the 

 tabulated data and cross-section drawings J"' There is only a brief 

 description of results and no attempt is made to relate the present 

 work in a comprehensive fashion to that done by others in the equa- 

 torial Pacific. 



The primary objective of these oceanographic studies in 

 the equatorial Pacific is to provide information that may be related 

 to biological productivity and particularly to the occurrence of the 

 tunas, POFI's oceanographic program, up to the present time, has 

 centered on describing the distributions of physical and chemical 

 properties and on determining the regions where vertical motion of 

 a type important to productivity occurs 



Vessel, Equipment , a nd Procedures 



Vessel and ves sel equipment; The Hugh M. Smith is a 

 former U. S„ Navy YP of 700 dead weight tons, converted to carry 

 out oceanographic and fishing research Q A previous report (Cromwell 

 1951) provides a photograph of the vessel and describes the oceano- 

 graphic and other scientific equipment aboard Q 



Collection of data; The methods used at sea to collect 

 physical and chemical data were essentially as described in the re- 

 port mentioned above„ Serial temperature observations were made 

 using protected reversing thermometers. Water samples were ob- 

 tained using Nansen-type bottles (see frontispiece). The concentra- 

 tions of dissolved oxygen were determined by the Winkler titration 



2/ All cross -sections and tabulated data are grouped at the end of 

 the text 



