Table 4. --Average volumes of zooplainkton from three-net hauls on HMS-32, 34, and 35, and 



from two-net hauls on HMS-36 



Table 5. --Average ratios of volume of zoo- 

 plankton in various strata of water sampled 

 by three nets on HMS-32, 34, and 35, and by 

 two nets on HMS-36 



Table 6. --Average volumes of zooplankton in 

 two strata of water during different 

 periods of the day on CHG-24 



the quantity of zooplankton from the lower 

 stratum. During the day, average volumes in 

 the upper stratum were only slightly larger 

 than in the middle stratum. The ratio increased 

 from near unity during the day to about 1.5 at 

 night, probably as a result of the movement of 

 zooplankton toward the surface at night. 



The evidence of a greater concentration of 

 zooplankton in the upper layers, both at night 

 and during the day, is in agreement with the 

 findings of King and Hida (1957) and others. 

 From open-net. oblique hauls to a depth of 100 

 m.. King and Hida (1957) obtained average vol- 

 umes 1.6 times the average volumes from hauls 

 to a depth of 200 m. Coincidentally , the same 

 ratio. 1.6, was obtained during CHG-24. when 

 the average unadjusted volume from the shal- 

 low, open-net, oblique hauls between the sur- 

 face and the top of the thermocline (average 

 depth 78 m.) was divided by the average unad- 

 justed volume from the hauls at the alternate 

 stations between the surface and 200 m. (table 



Surface to 200 m. 



All periods 

 Day 



Twilight 

 Night 



6). Volumes of zooplankton again were greater 

 in the upper stratum, regardless of the time of 

 sampling. 



Horizontal Distribution 



The region sampled in the comprehensive 

 series was subdivided into leeward and wind- 

 ward areas (fig. 2), for comparisons of abun- 

 dance of zooplankton for each cruise (table 7). 

 (In the Hawaiian Islands, the prevailing winds 

 are from the northeast most of the year.) Dif- 

 ferences between the two areas were significant 

 only in the upper net, and only during November 

 1955 (CHG-24) and May 1956 (HMS-34). 



