Oceanographic Observations Hydrographic Stations: Between Kwajalein and Yokosuka, 12 bottle casts to ap- proximately 600 m were made at approximately 180 mile intervals (stations numbered 1, 2, 3, etc., see Figure eight and Appendix A for positions}. servations were taken at the following approximate depths: 200, 300, 400, 500 and 600 m. On these stations, ob0, 10, 25, 50, 75, 100, 150, On Stations 42 and 45 additional observations at 800, 1000 and 1200 m were taken. On each station at each depth, the following observations were taken: a) Temperature. Subsurface temperature measurements were taken with protected reversing thermometers. Below 100 m, unprotected reversing thermometers were used to determine depths of observations. Reversing thermometer temperatures are believed to be accurate to t 0.02°C. b) Salinity. Water samples were saved and subsequently titrated at the Scripps Institution, c) + 0,03 percent. Radiochemistry. Salinity values are believed to be accurate to Water samples were collected for subsequent radio- chemical analysis (see below}. Supplementary Stations: After Station 12, supplementary 4-bottle casts to approximately 400 m were madehalfway between hydrographic stations (stations numbered 12A, 13A, etc.; see Figure eight and Appendix A for positions). On these stations observations were taken at the following approximate depths: 0 (bucket}, 50, 100, 200, 400 m. No thermometers were used and depths were estimated from wire angle. Bathythermograph Observations: Subsurface temperature measurements to about 250 m were taken every hour (at about 15 mi intervals) while underway, with the bathy- thermograph. Surface Temperature: A continuous record of surface temperature was kept by means of a recording thermograph. The thermograph sensing element was located in a well ina sea chest in the engine room. Biological Collections Standard Net Tows: On all hydrographic stations, supplementary stations and between each hydrographic station prior to Station 12, standard oblique plankton tows were made. The nets used measured ] m in diameter at the mouth and about 5 m in over-all length and were constructed of No. 30xxx grit gauze which retains organisms larger than about 0.5-mm diameter. An Atlas-type current meter fastened in the mouth of the net was used to measure the volume of water strained during the haul. Tows were made in the following manner: with the vessel steaming at 1-2 kts, the net was lowered at 50 m/min until 300 m of wire was out, then was retrieved at a steady rate of 30 m/min. It is believed that the collections represent a quantitative measure of zooplankton organisms larger than 0.5 mm present in the upper 200 m of water. After collection, plankton samples were split, half being retained by Scripps for zoogeographical analysis, a quarter being used for shipboard radiochemical analysis, and a quarter being retained for radiochemical analysis at the Applied Fisheries Laboratory, University of Washington. Microplankton Tows: After Station 23, on each hydrographic station a short ver- tical tow was taken with a 17-cm No, 20 net. Although they are nonquantitative, it is believed that the collections represent a sampling of small (larger than 0.1 mm) phytoplankton and zooplankton organisms living in the surface waters. These samples were used in entirety for shipboard radiochemical analysis. % ae yo AG i vit 7