observations were planned so that theHBL data 

 would extend and supplement those collected 

 during the same period from vessels of the 

 Seattle Biological Laboratory, which were 

 operating near the Aleutian Islands and in the 

 Bering Sea. 



Outside the area the 13 -bottle casts to 

 1,200 meters were made at approximately 90- 

 mile intervals. Inside the albacore survey area 

 the interval was shortened to permit a more 

 detailed study of the geostrophic current struc- 

 ture. Except for the stations occupied on either 

 side of the temperature front centered at 

 41°31'N., 175''07'W., the interval between sta- 

 tions ranged from 30 to 60 miles. The actual 

 spacing depended to a large extent upon when 

 they could best be worked into the operational 

 schedule . 



Samples for salinity, inorganic phosphate, 

 and dissolved oxygen were drawn from each 

 Nansen bottle. Surface salinities and inorganic 

 phosphate sannples were also collected at the 

 location of between-station bathythermograph 

 casts. The salinity samples were returned to 

 HBLfor analysis, and the dissolved oxygen and 

 inorganic phosphate samples were analyzed 

 aboard ship. The oceanographlc station data 

 are given in table 13 and those from the bathy- 

 thermograph casts In table 14. 



Surface salinity samples were taken at 

 most locations of bathythernnograph casts from 

 the Paragon . The analyses were made at the 

 Seattle Biological Laboratory. The results are 

 listed in table 15. 



Water temperature. --The recording 

 thermograph aboard the Smith was operated 

 continuously. Bathythermograph casts were 

 made before and after each oceanographlc cast 

 and each longllne set (see table 14 for station 

 data and figs. 4-13 for profiles). On runs be- 

 tween stations, they were made at 30-mlle 

 Intervals outside the albacore survey area and 

 at intervcils of 15 miles or less Inside the area. 

 In the latter case the Interval was frequently 

 shortened to make the casts coincide with troll 

 catches, Secchldlsc lowerlngs, or C-14 samples. 

 Atthe front encountered at 41°30'N. , 175°07'W. , 

 where the temperature increased from 61. 5°F. 

 to 63. 5°F. In 4 miles along a north-south course, 

 a series of BT casts were made at 1-mlle 

 Intervals . 



Thlrty-slx bathythermograph casts were 

 made from the Para gon to a depth of 180 feet. 

 All but one were at glU-net stations. The sta- 

 tion data are given in table 15. 



Meteo rologi cal observations . --Synoptic 

 marine weather observations were made on the 

 Smith at 0000, 0600, 1200, andlSOO GCT dally. 

 They were recorded In the I nternational Ship's 

 Weather Code (U.S.W.B. 1954) and transmitted 

 to either the U. S. Weather Bureau at San 

 Francisco, California or Honolulu, Hawaii, 

 whenever radio conditions permitted. The 

 observations are listed In table 16. 



Subsurface Illumination observations. -- 

 Observations of subsurface Illumination were 

 made from the Smith with both the Schuler sub- 

 marine photonneter and the Secchl disc. Only 

 the Secchldlsc was used from the Paragon. The 

 Schuler photometer and method of operation 

 have been described by Callaway (1957). Lower- 

 lngs were made once per day until the Instru- 

 mentfalledat station 27. The results are listed 

 In table 17. 



Secchl disc observations from the Smith 

 were made at approximately local noon each day 

 when the weather permitted. Additional observa- 

 tions were made In the vicinity of the temperature 

 front mentioned above. The results are Included 

 in table 1. Secchl disc lowerlngs from the 

 Paragon were made at the location of bathy- 

 thermograph casts (table 15). 



LABORATORY METHODS AND TECHNIQUES 



Most of the procedures used In the anal- 

 ysis of the Scimples have been described In earlier 

 reports. The dissolved oxygen analyses were 

 made aboard the Smith by the standard Winkler 

 nnethod described In U. S. Navy Hydrographlc 

 Office Pub. 607 (1955). 



The inorganic phosphate determinations 

 were analyzed by the hydrazine sulphate modi- 

 fication of Denigi's method developed by Van 

 Landingham (King et al. 1957). The determina- 

 tions for stations 1 to 11 were made with the 

 Automatic Servo-operated Photometer described 

 by Wooster and Raksstraw (1951). After station 

 11 this instrument failed and a Beckman photo- 

 meter was used. 



The salinity determinations at HBL were 

 made by a modification of Fajan's adsorption 

 Indicator method developed by Van Landlnghann 

 (1957). 



The reduction of the protected thermo- 

 nneter readings to true water temperature and 

 the thermometrlc deternnlnatlonof the sampling 

 depths were done using graphical methods des- 

 cribed by La Fond (1951). 



