The standard tow in 1972 was an oblique haul to ca. 210 m 

 depth (to 15 m of the bottom in shallow areas) designed to filter 

 a constant amount of water per depth interval (ca. 3m /m of 

 depth) over the vertical range of most ichthyoplankters. Hauls 

 were made at a ship speed of 1.5-2.0 knots and initiated by 

 clamping the net line to the towing cable with the 4 5 kg terminal 

 weight about 10-15 m below the surface. The net was lowered to 

 ca . 210 m depth by paying out 300 m of wire over a 6 minute 

 period (35 m of depth/min.). After fishing at depth for 30 

 seconds, the net was retrieved at 20 m/min. (14 m depth/min.). 

 The angle of stray of the towing cable was recorded every 3 

 seconds and maintained at 45° (+3°) by adjusting the ship speed 

 and course. After reaching the surface, the net was washed down 

 and the samples preserved in 5% formalin buffered with sodium 

 borate. Flowmeter readings were made at the beginning and end of 

 each tow. Detailed descriptions of gear and methods are given by 

 Kramer et al . (1972), and Smith and Richardson (1977). 



LABORATORY PROCEDURES 



Laboratory processing began with the determination of a 

 displacement volume for each sample (methods described in Staff, 

 SPFI, 1953 and Kramer et al., 1972). Sorting involved the 

 removal of ichthyoplankton from the sample and identification and 

 separation of: eggs and larvae of Pacific sardine and northern 

 anchovy; larvae of Pacific hake; and eggs of Pacific saury. 

 Usually, each sample was sorted completely; however, in 1972, 

 some of the samples from two of the six cruises were fractioned 

 into aliquots using a Folsom plankton splitter (McEwen et al., 

 1954) prior to sorting. Samples collected in Cruise 7202 by the 

 Soviet research vessel Alba were fractioned to 50% of the 

 original volume. Samples from Cruise 7207 were fractioned to a 

 25% aliquot if the sample was collected within 200 miles from the 

 coast and its original volume exceeded 25 ml (J. R. Thrailkill, 

 pers. comm.). Aliquot percentages for fractioned samples from 

 1972 are listed in Table 1 under the "Percent Sorted" column. 



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) 



