sea surface at sunrise and local noon. Water 

 was placed in clear ("light") and opaque 

 ("dark") 125-ml. glass-stoppered Pyrex 

 bottles. Each sample was inoculated with 1 ml. 

 of C^'* solution (1.7 microcuries/ml.) and 

 trailed from sunrise to local apparent noon or 

 from local apparent noon to sunset. After 

 incubation, samples were immediately filtered 

 through 25-mm. membrane filters (0.30- 

 micron (//)i.02-// pore size - manufacturer's 

 rating). The filters were rinsed with 2 ml. of 

 0.05 N HCl and placed in a vacuum dessicator 

 for counting ashore. 



Surface chlorophyll samples were obtained 

 at 28 stations (fig. 12, tables 1 and 6). Three 

 surface water samples of 2.0-3.0 liters each 

 were taken at the same time that water was 

 taken for primary production measurement. 

 These were filtered immediately through 47- 

 mm. membrane filters (0.45-i/ +..02-// pore 

 size). Small amounts of magnesium carbonate 

 were added during filtration. The filters were 

 dessicated and frozen for shore analysis of 

 chlorophyll a.. 



Oblique zooplankton hauls were made at 

 10 noon stations, coincident with hydrographic 

 and productivity stations (tables 7 and 8). 

 Samples were collected with a 1 -meter net 

 identical to those used on cruises of the Cali- 

 fornia Cooperative Oceanic Fisheries Investi- 

 gations (e.g., Thrailkill, 1956)andof the Pacific 

 Oceanic Fisheries Investigations (King and 

 Demond, 1953). Calibration of the water-flow 

 meter was done before and after the cruise. 

 The meter was affixed to a towing frame and 

 hauled back and forth through a 50-ft. water 

 course at 13 speeds from 1.3 to 3.6 ft./sec. 

 Revolutions/sec. recorded at each speed, aver- 

 aged to cancel current effects, were plotted 

 against distance traversed/revolution to estab- 

 lish a calibration curve. Water volumes re- 

 corded on net hauls were calculated by 

 multiplying the net-mouth area by the distance 

 traversed as indicated by the flow meter. No 

 extensive clogging of the plankton net was 

 evident during the cruise. 



Trolling for albacore was conducted between 

 stations at 6 to 8 knots with six to eight lines. 

 Feather jigs were used, supplemented occa- 

 sionally by bone-type jigs. About 205 hours 



were spent trolling, generally from one-half 

 hour before sunrise to one-half hour after sun- 

 set. Sixty albacore were caught (fig. 13, table 

 9); six of these were released wearing tags 

 supplied by the Fish Commission of Oregon. 

 Blood samples were taken from 16 albacore 

 for serological analysis by Lucian Sprague of 

 the Bureau of Commercial Fisheries Biologi- 

 cal Laboratory, Honolulu. 



Nightly sets of eight shackles (400 fathoms) 

 of gill nets were made between July 11 and 

 July 17 (table 10). On the morning of July 18, 

 the nets could not be found; probably the nets 

 sank under a load of blue sharks, Pnonace 

 glauca (Linnaeus). Many had been enmeshed on 

 previous sets. Two albacore and one bluefin 

 tuna, Thunnus thynnus (Linnaeus), were caught 

 on the set of July 14-15 at station H-7 (fig. 13). 



LABORATORY PROCEDURES 



Salinity determinations were made through 

 the courtesy of the Department of Oceanog- 

 raphy, University of Washington, on a conduc- 

 tivity bridge calibrated against Copenhagen 

 Water (figs. 3, 6, and 9; table 2). Accuracy is 

 better than ±0.005 ^^ . 



Oxygen determinations (table 2) were made 

 on board the vessel by the Winkler method 

 according to procedures outlined by Wooster' 

 and Chow.* 



Chlorophyll samples were transported under 

 refrigeration to San Diego for analysis (fig. 12, 

 table 6). The method of analysis used was that 

 described by Holmes and others (1958), except 

 that extraction in acetone was allowed to pro- 

 ceed for 16-18 hours. Equations used in calcu- 

 lation of chlorophyll a_ are those of Richards 

 with Thompson (1952). 



'Warren S. Wooster. 1950. Methods in chemical 

 oceanography employed in the California Cooperative 

 Sardine Research Program. Technical Report of 25 No- 

 vember 1950, Scripps Institution of Oceanography, 27 p. 

 Mimeographed. 



*T. J. Chow. 1961. Field guide for the STEP-I Expedi- 

 tion. Scripps Institution of Oceanography, 35 p. Mimeo- 

 graphed. 



