orrsHom sonvtr 





IHSHOKf suKvey 



Figure 2. 



-Standardized inshore and offshore 

 survey tracks, Marquesas area. 



FIELD PROCEDURES 



Bathythermograph and Meteorological 

 observations 



Except where noted below, bathythermo- 

 graph (BT) lowerings on the four cruises were 

 made according to the following schedule: every 

 6 hours between Honolulu and latitude 11°N., 

 every 3 hours between latitude 11°N. and 

 the Marquesas, local noon daily in the Marque- 

 sas area while on both inshore and offshore 

 surveys, every 3 hours on the offshore 

 survey, at each tuna fishing station, and every 

 6 h o u r s on the run between Tahiti and the 

 Marquesas . 



BT lowerings during cruise 38 of the 

 Gilbert were made every 6 hours enroute 

 from Honolulu to the first longline fishing sta- 

 tion at latitude 5°N., longitude 150°W. Three 

 lowerings were made at each of the seven fish- 

 ing stations; one innmediately after setting, the 

 second just prior to retrieving, and the third 

 immediately after retrieving the longline gear. 

 One BT lowering was made mid-way between 

 fishing stations along 150°W. longitude (fig. 1). 

 Aside from the foregoing deviations, BT lower- 

 ings were made following the schedule listed 

 above. 



The BT schedule followed during cruise 

 45 of the Smith differed only in that lowerings 

 were made every 6 h o u r s to latitude 4°N. on 

 the run south from Honolulu. 



Nine hundred-foot BT's 

 were used on all the cruises. Ob- 

 servations made in conjunction 

 with BT lowerings were coded ac- 

 cording to H. O. Pub. 606-c, and 

 recorded on Oceanographic Log 

 Sheet B. These observations are 

 presented in tables 2, 3, 4, and 5. 

 The observations made during 

 that portion of Smith cruise 45 

 concerned with the Undercurrent 

 are not included here. 



BT lowerings totalled 295 

 during Gilbert cruise 35, 263 

 during Smith cruise 43, 336 dur- 

 ing Gilbert cruise 38, and 264 

 during Smith cruise 45. 



Determinations from analy- 

 ses of surface salinity ajid surface 

 inorganic phosphate samples taken 

 at BT lowerings are included in 

 tables 2, 3, 4, and 5. Surface 

 salinity values plus surface 

 temperatures for locations other 

 than BT lowerings are presented 

 in table 10. Both the surface salinity and 

 surface inorganic phosphate samples were 

 returned ashore for analysis with the exception 

 that some phosphate samples were analyzed 

 aboard the vessel during Smith cruise 45. The 

 phosphate samples were frozen as a means 

 of preservation. 



During the four cruises , standard weather 

 observations were made up to 4 times daily. 

 They were omitted when the vessels were in 

 bays or harbors, and were made sporadically 

 during fishing periods. The observations, as 

 encoded according to U. S. Weather Bureau 

 Form 1210-F, are presented in tables 6, 7, 8, 

 and 9. Weather observations made during the 

 Undercurrent survey portion of the Smith are 

 not included in table 9, and will be presented 

 elsewhere. 



Productivity observations 



Water color and transparency observa- 

 tions were made routinely at local noon daily, 

 during survey periods in the Marquesas area. 

 The transparency measurements were made by 

 lowering a 30-cm. Secchi disc. The 

 water color observations were made by com- 

 parison with the Forel standard. In addition, 

 photometer readings were made during Smith 

 cruise 45 at the diurnal variability station 

 (9°34'S., 139°50'W) and between 5°S. and 

 10°N. on the run between the Marquesas and 

 Honolulu. These and related data are presented 

 in tables 11, 12, 13, and 14. 



