Prior to the setting of the nets the 

 routine began with a 20-minute surface 

 plankton haul on a circular course. Then 

 the gill nets were set and the remainder of 

 the oceanographic routine was accomplished 

 while the vessel was moored to the downwind 

 end of the net. 



The deep cast required an hour or 

 more, depending on the adversity of the 

 weather and sea conditions. When the biol- 

 ogist was able to assist with the vertical 

 plankton hauls, these were made between 

 hydrographic casts after taking and analyz- 

 ing the 900- foot BT trace. Without this 

 assistance the plankton hauls were made 

 after the shallow cast. Thus the plankton 

 hauls, shallow cast, and BT trace were 

 usually made within an hour of each other. 



Secondary Stations 



Secondary stations, taken between 

 fishing stations without interrupting the 

 cruise plcin, consisted of a 900-foot BT 

 and one shallow cast to 125, 150, or 170 

 meters. These stations were taken at the 

 1000-fathora curve on north-south transits 

 through the Aleutian Passages, and at vari- 

 ous locations on the return voyages when 

 weather permitted. 



Hydrographic Casts 



The observers made two casts of seven 

 Nansen bottles at primary stations. Early 

 spacing was 10, 20, 30, 50, 80, 110, and 

 140 meters for the shallow cast and 170, 

 200, 250, 300, 500, 800, and 1100 for the 

 deep cast. These were later changed to 10, 

 20, 30, 50, 75, 100, 125, and 150, 175, 

 200, 300, 500, 800, 1100 meters in order to 

 obtain more data in the upper 200 meters of 

 the water column. 



Each Nansen bottle had two protected 

 reversing thermometers. Three or four 

 bottles in each cast had an unprotected 

 thermometer, usually in positions 1, 5,7 

 or 1, 4, 5, 7. 



phosphate samples also from the surface. 



Bathythermograph Lowerings 



Using 900- foot BT's almost exclusive- 

 ly, the observers obtained traces at every 

 hydrographic station cuid at intervals of 

 20-30 miles enroute between stations, col- 

 lecting a total of 669 traces. The vessels 

 stopped for each lowering. 



Plankton 



Plankton samples were taken from both 

 horizontal tows and vertical hauls with 

 1/2-meter nets of #6 mesh. 



The horizontal tow was made at the 

 surface at a speed of about 3 knots for a 

 period of 20 minutes. The data from these 

 tows are not presented because early in the 

 cruises considerable amounts of phytoplank- 

 ton were obtained that prevent amy quanti- 

 tative analysis of zooplankton, and the 

 tows were discontinued because of repeated 

 damage to the nets. Visual examination of 

 the samples obtained indicate no signifi- 

 cant qualitative difference from the upper 

 vertical haul. 



Three vertical hauls were made to 

 determine vertical distribution of plankton. 

 Hauls from 300 meters to the surface, from 

 300 meter to the bottom of the thermocline, 

 and from the thermocline to the surface, 

 were made at a velocity of approximately 

 50 meters per minute. However, individual 

 interpretations of the BT traces do not 

 rigorously define the bottom of the thermo- 

 cline, and station data should be used to 

 determine the relative position in the 

 thermocline at which the latter two hauls 

 were commenced or terminated. 



Nightlight Observations 



Because of generally unsatisfactory 

 weather and sea conditions, only a few 

 nightlight samples were collected. They 

 have not been tabulated. 



Water Samples 



On each station and at every BT lower- 

 ing, the observers dipped surface samples 

 by bucket. They drew samples for analysis 

 of dissolved oxygen and phosphate from four 

 alternate depths in each cast, and for chlo- 

 rinity from all depths; they collected some 



Drift Bottles 



A total of 473 drift bottles were re- 

 leased individually in groups of 24 or 48 

 at various locations which are presented in 

 table 4 (page 106). Figure 2 shows a sample 

 bottle. Each group of 24 had a single 

 serial number. 



