The voliune of water strained during a havil was determined from the 

 formtilation: 



V = E'B'p 



in which 



a - the cross-sectional area of the mouth of the net in 

 square meters 



p - length of the column of water in meters needed to effect 

 one revolution of the current meter at the average speed 

 at which the haul was taken (determined from the appro- 

 priate calihration graph) 



E - total numher of revolutions registered by the current 

 meter during a haxil 



7 - total volume of water strained in cubic meters during a 

 haul 



VERTICAL DISTRIBUTION OF SARDINE IGGS AMD LARVAE 



The distribution of plai^kton organisms in the ocean can be considered 

 to be four dimensional, if the time component is included as one of the 

 dimensions. Of these, the vertical component is the easiest to deal with, 

 as often it can be completely encompassed. Sampling of both the time and 

 horizontal distributions, however, are necessarily spotty. 



Fortunately, most fish eggs and larvae occur in the euphotic zone, 

 usually in the upper 100 meters of depth. It has been shown that most sar- 

 dine eggs and larvae occur above ^ meters in depth, and all above 100 meters. 

 Hence, our routine hauls, which sample a depth stratum of approximately 

 ll^-O meters, should effectively encompass the depth distribution of sardine 

 eggs and larvae. 



VARIATION IN DEPTH OF PLANKTON HAULS 



Because of unavoidable variations in speed of towing, hauls differed 

 in the depth of the stratum sampled. At a hi^er speed than usual, the net 

 went less dbep and spent more time in each unit of depth traversed. For 

 hauls taken at a s3.ower vessel speed than usual, the reverse was true. 



