Figure Ig. --Vessel track of Charles H. Gilbert cruise 46, Sept. Z9-Oct. 18, 1959. 



FIELD PROCEDURES 



Bathythermograph and Meteorological 

 Observations 



Bathythermograph (BT) lowerings were 

 made every 3 hours on Hugh M. Smith cruises 

 50 and 51, and approximately every 30 miles on 

 Charles H. Gilbert cruises 44, 45, and 46. The 

 observations of weather and sea at each BT low- 

 ering appear in tables 2 to 6. The BT slides, 

 prior to deposition in the U.S. Navy Hydro - 

 graphic Office, were processed at the Labora- 

 tory by the method described by Callaway (1957) . 



Weather observations were recorded at 

 0000, 0600, IZOO, and 1800 GOT daily. These 

 data are presented in tables 7 to 11 (U.S.Weath- 

 er Bureau Form 1210 -F). Recording and coding 

 follow the "Manual of Marine Meteorological 

 Observations" (U.S. Weather Bureau, 1959). 



Light Penetration and Water Color 



Secchidisc observations and For el water 

 color estimations from Hugh M. Smith cruises 

 50and 51 and Charles H. Gilbert cruises 45and 

 46 are tabulated in table 12. These observations 

 were taken at local apparent noon. 



Zooplankton Collections 



Of the 139 plankton hauls, 107 were 1/2- 

 hour, 0- to60-m. oblique hauls at approximately 

 2100 hours. In addition, 24 surface tows of 20- 

 minute duration were taken during Charles H. 

 Gilbert cruise 45 to collect larval tunas for se- 

 rological studies . On Charles H. Gilbert cruise 

 46, five 1/2-hour surface hauls were takenacross 

 a temperature discontinuity encountered south 

 of the island of Molokai. Three oblique - to 

 140 -m. hauls were taken during Hugh M. Smith 

 cruise 50 for comparison with plankton hauls 

 taken at similar depths during previous cruises. 

 Zooplankton sample weights are given in tables 

 13-17. The major group composition for select- 

 ed samples is given in table 18. 



All plankton hauls were made using a 1- 

 meter net with body of No. 656 Nitex, aperture 

 widths 0.66 mm., and with cod end of No. 308 

 Nitex, aperture widths 0.31 mm. ( King and 

 Demond, 1953). 



Surface Fish School, Bird Flock, 

 and Aquatic Mammal Sigh'.ings 



A watch was maintained for surface fish 

 schools, birds, and aquatic mammals during 



