SAN FRANCISCO 



Figure Z. --Track of N. B. Scofield cruise 59S4. 



of Commercial Fisheries Biological Laboratory, 

 Honolulu, using methods described by Callaway 

 (1957). 



Continuous records of surface tempera- 

 ture were obtained along the cruise tracks of 

 both vessels by means of recording thermo- 

 graphs . 



Light Penetration and Water Color 



Light penetration measurements were 

 made from the Smith with a photometer and a 

 Secchi disc, and water color was determined 

 with a Forel color scale. Secchi disc measure- 

 ments were also made from the Scofield. By 

 means of the photometer , described by Callaway 

 (1957), we determined the depths to which 50 

 percent, 10 percent, 5 percent, and 1 percent of 

 sunlight were transmitted. Usually these meas- 

 urements were made at noon (LCT). In a few 

 instances observations were made from the 

 Smith during the morning hours, but they were 

 discontinued because it was found that there was 

 insufficient sunlight to produce reliable readings. 



Light penetration and water color data and the 

 average illumination on deck are given in tables 

 4 and 5 . 



Salinity and Inorganic Phosphate 



Surface salinity samples were collected 

 coincident with each BT cast from both the Smith 

 and Scofield . Samples were also obtained from 

 the Smith fishing stations. Surface water sam- 

 ples, frozen for subsequent analysis of their in- 

 organic phosphate content, were obtained from 

 the Scofield with each BT cast. On the Smith, 

 samples for phosphate analysis were collected 

 at BT casts at approximately 90 -mile intervals 

 between Oahu and point B (32° N. , 127° 30' W . ), 

 and at 30 -mile intervals east of point B; they 

 were also collected at every fishing station. All 

 salinity and inorganic phosphate samples were 

 analyzed at the Bureau of Commercial Fisher- 

 ies Biological Laboratory, Honolulu. Salinity 

 samples were processed using a modification of 

 the Mohr method (Van Landingham, 1957) and in- 

 organic phosphate by a modification of the molyb- 

 denum method using the Beckman Photometer 

 Model B (King etal., 1957). The data taken 



