The standard tow in 1978 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. 2m /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 to the towing cable with a 34 kg terminal weight 

 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 3 seconds, the net was 

 retrieved at 2 m/min. (14 m depth/min.). The angle of stray of 

 the towing cable was recorded every 30 seconds and maintained at 

 45° (+3°) by adjusting the ship speed and course. After reaching 

 the surface, the nets were 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. Descriptions of 

 the methods are given by Kramer et al. (1972) and Smith and 

 Richardson (1977) . The bongo net frame is described in McGowan 

 and Brown (1966) 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. Some 

 samples were fractioned into aliquots using a Folsom plankton 

 splitter (McEwen et al., 1954) prior to sorting. Criteria for 

 fractioning were: 1) samples taken at a distance greater than 

 200 nautical miles from shore were not fractioned, 2) samples 

 taken closer than 200 miles from shore and containing 25 ml of 

 plankton or less were not fractioned, and 3) samples taken 

 closer than 200 miles from shore and containing more than 2 5 ml 

 of plankton were fractioned to 50% of their original volume (J. 

 R. Thrailkill, pers. comm. ) . Aliquot percentages for fractioned 

 samples from 1978 are listed in Table 1 under the "Percent 

 Sorted" column; 46.4% of the samples collected in 1978 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 



