SUMMARY, OCEANOGRAPHIC AND BIOLOGICAL DATA, 

 MARQUESAS ISLANDS AREA, 

 AUGUST-SEPTEMBER, 1956 (EQUAPAC) 



By 



Thomas S. Austin, Oceanographer 



Pacific Oceanic Fishery Investigations 



U. S. Fish and Wildlife Service 



Honolulu, T. H. 



In recent years a number of descriptive 

 and theoretical papers have been published, 

 each describing various sectors of the Pacific 

 equatorial circulation. The need for a multiple- 

 vessel, quasi-synoptic, oceanwide survey of the 

 area became apparent. A formal plan for such 

 a survey, named EQUAPAC, was adopted in 

 February 1956 at a conference in Honolulu. The 

 Japanese Hydrographic Office and the Pacific 

 Oceanic Fishery Investigations (POFI) of the 

 U. S. Fish and Wildlife Service were designated 

 as coordinating agencies. Participating vessels 

 included those from various Japanese oceano- 

 graphic and fishery laboratories, the French 

 Oceanographic Institute at Noumea, the Scripps 

 Institution of Oceanography, and POFI. The 

 tracks of the various vessels are shown in the 

 frontispiece of this report. 



POFIassigned two vessels to EQUAPAC, 

 the Hugh M. Smith for the oceanographic and 

 the Charles H. Gilbert for the fishing surveys. 

 The multiple -vessel expedition was fortunately 

 timed so that POFI's participation could be con- 

 sidered as a part of an already scheduled pro- 

 gram in the Marquesas -Tuamotus area. Thus 

 the data from the Smith and the Gilbert may be 

 evaluated both with reference to the data 

 collected simultaneously by other vessels during 

 EQUAPAC and also with reference to data which 

 will be collected in other seasons by our own 

 ships in the Marquesas -Tuamotus area. The 

 oceanographic and biological data collected from 

 the Smith and the Gilbert are presented in this 

 report, along with a brief narrative text and 

 descriptions of the variations from the routine 

 POFI field and laboratory techniques reviewed 

 in earlier reports. 



The Smith departed Honolulu on August 

 7, 1956 occupied oceanographic stations as 

 shown in figure 1 , and returned to Honolulu on 

 October 5, 1956. The Gilbert departed Honolulu 

 on August 6, 1956, conducted fishing and baiting 

 operations at the positions shown in figures 2 

 and 3, and returned to Honolulu on September 

 26, 1956. 



X OCEANOGRAPHIC 1200 M CAST 

 (3) OCEANOGRAPHIC 3000 M CAST 



D DEUTERIUM 

 R(C) RADIOACTIVITY (CML) 

 R(S) RADIOACTIVITY (SIO) 



Figure 1. --Track chart showing observa- 

 tions conducted during H ugh M. Smith 

 cruise 35 (EQUAPAC), August 1 - 

 October 5, 1956. 



The primary missions of the Smith 

 were to conduct detailed chemical, physical, 

 and biological observations in order to delineate 

 the gross, oceanic circulation features and 

 obtain information on the variations in abund- 

 ance and distribution of the biota in respect to 

 the environment. The program for the Gilbert 

 was designed to evaluate the tuna resources, 

 principally in the area around the Marquesas , 

 by longline and live -bait fishing, by trolling, 

 and by visual observations of fish schools and 



