7 - 



Animals from Night -Light Collections (W. L. Klawe) 



The results of the dlpnetting under the night light 

 (see methods) are shown in table 2. An effort to 

 classify to the specific level was made only in the 

 case of juvenile tunas. Tunas collected during this 

 expedition are: Katsuwonus pelanus , Euthynnus 

 lineatus , and Auxis thazard . Organisms which were 

 observed and recognized beyond any doubt, but not 

 collected, are included in this table. Most of the fish 

 caught under the night light were juvenile forms, but 

 this is not true in all cases as many Myctophidae, 

 Hemiramphidae, Exocoetidae, and some others were 

 adult individuals. One animal has been omitted from 

 the table. It is the ubiquitous Halobates which was 

 observed at all night stations. 



PROCEDURES 



generally commencing at midnight (local time). The 

 general procedure was as follows: 



1. Oblique nekton net tow to depth of about 90 m. 



2. Oblique zooplankton meter-net tow to a depth of 

 about 300 m. 



3. Surface zooplankton meter-net tow. 



4. Dipnetting under night light, when conditions 

 were favorable. 



5. 900 ft bathythermograph lowering with surface 

 salinity sample and general weather observa- 

 tions. (Sometimes omitted. ) 



In Situ and Other Special Stations 



Regular Forenoon Stations 



At approximately 1030 (local time) each day a station 

 was occupied. The general procedure at these sta- 

 tions was as follows: 



1. 900 ft bathythermograph lowering accompanied 

 by general weather observations. 



2. Nansen bottle cast to a depth of approximately 

 1000 m. The water samples were employed for 

 the determination of salinity, oxygen and inor- 

 ganic phosphorus, all of which were analyzed on 

 shipboard. 



3. 50-0 m phytoplanlrton net haul. A 17-cm truncate 

 net with a mesh size of 32 |i was employed. 



4. Two plastic sampler casts, each to a depth of 

 about 100 m. The samples were used for pro- 

 ductivity studies and for clilorophyll a. determi- 

 nations. 



5. Oblique zooplankton meter-net tow to a depth of 

 about 300 m. 



6. Surface zooplankton meter-net tow. 



7. Submarine photometer lowering, to approxi- 

 mately 100 m. 



Regular Night Stations 



It was the practice to occupy a station each night. 



The above-mentioned routine, one forenoon and one 

 night station per day, was modified in a number of 

 areas, as follows: 



1. In situ productivity stations (Nos. 4, 23, 49, 56, 

 62, 88) were essentially extended forenoon sta- 

 tions. The extra operations were in situ meas- 

 urement of productivity (C-^^ method) and hori- 

 zontal closing-net zooplanldon tows at three 

 depths (in mixed layer, in thermocline, and be- 

 low thermocline at about 100-200 m). 



2. Island surveys. For the purpose of investigating 

 zooplankton standing crop gradients near islands 

 in the way described above (Summary of Pre- 

 liminary Results), several stations were occupied 

 for the sole purpose of making zooplankton and/or 

 nekton net tows (9, 11, 12, at Clarion Island; 

 19-21, 24-26, at Clipperton Island; 52, 53, 55, 



at Cocos Island); in addition to stations which 

 wei'e regular forenoon, night, or in situ stations 

 (8, 10, 13, at Clarion; 22, 23, 27, at Clipperton; 

 51, 54, 56, at Cocos). Bathythermograph lower- 

 ings were made at some of these special stations. 



3. Gulf of Tehuantepec sui-vey. Several stations 

 were occupied in this area for the purpose of 

 making Nansen bottle casts and zooplankton net 

 tows only (78, 80, 82, 84, 87, 89, 91-94); in 

 addition, three regular forenoon stations (79, 83, 

 86), one in situ productivity station (88), and 

 four regular night stations with Nansen bottle 

 cast added (77, 81, 85, 90) were occupied. Bathy- 

 thermograph lowerings were made at all the 



