1954) prior to sorting. Several criteria were used to determine 

 whether a sample was fractioned: samples containing an abundance 

 of thaliacians and coelenterates and exceeding 150 ml in total 

 plankton volume were fractioned (to 50%, 25%, 12.5%, or 6.25%) to 

 approximate a reduced volume of 50 ml for sorting; samples with 

 an excessive quantity of fish eggs and/or larvae were 

 occasionally fractioned to expedite the sorting process in order 

 to meet scheduled deadlines. If the identified fraction of an 

 aliquot yielded rare or interesting species of fish larvae, the 

 remaining fraction was frequently sorted and identified with the 

 intent of finding additional specimens. Aliquot percentages for 

 fractioned samples from 1959 are listed in Table 1 under the 

 "Percent Sorted" column; in 1959 less than 2% of samples were 

 fractioned. 



A "standard haul factor" (SHF) was calculated for each tow 

 to make them comparable and allow estimations of areal abundance. 

 This factor adjusts the number of eggs or larvae in a haul to the 

 number in 10 m of water strained per meter of depth fished. If 

 the vertical distribution of the species has been encompassed, 

 then the adjusted value is equivalent to the number under 10 m 

 of sea surface. The SHF is calculated for each haul by the 

 formula: 



SHF = 10 D 

 V 



where D = depth of haul = cosine of the average angle 

 of stray of the towing cable multiplied by 

 cable length (m) 



V = total volume of water (m ) strained 

 during the haul 



V 

 where R 



= R 



total number of revolutions of the current 

 meter during the haul 



a = area (m ) of the mouth of the net 



p = length of column of water (m) needed to 

 produce one revolution of the current 

 meter. 



Tow depth, volume of water strained, and standard haul factor are 

 listed in Table 1 for each tow taken during 1959. Detailed 

 descriptions of factors involved in calculating these values are 

 presented in Ahlstrom (1948), Kramer et al. (1972), and Smith and 

 Richardson (1977) . 



Personal communication, James R. Thrailkill, National Marine 

 Fisheries Service, Southwest Fisheries Center, La Jolla, CA. 



