the standard net was replaced with one constructed of nylon. 

 Construction of the nets was similar; however, the nylon net had 

 mesh sizes of 0.471 mm for the net body and 0.280 for the end of 

 the cone and the cod end (Smith, 1971) . The net ring was 

 fastened to a short 3-lead bridle connected to several meters of 

 line which attached to the towing cable by a clamp. A current 

 meter was suspended in the center of the net mouth to measure 

 volume of water filtered (see Kramer et al., 1972, for further 

 details) . 



The standard tow from 1951 through 1968 was an oblique haul 

 to 140 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 45 kg terminal 

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

 14 m depth by paying out 2 00 m of wire over a 4 minute period 

 (35 m of depth/min.). After fishing at depth for 30 seconds, the 

 net was retrieved at 2 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. 

 On the leg of Cruise 5908 occupied by the Hugh M. Smith, from 

 line 130 south (see Table 1) , tow depth was notably less than 

 usual. There was difficulty in maintaining ship speed less than 

 2 knots, which caused the net to fish shallower strata than 

 desired and resulted in low standard haul factors. 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 Ahlstrom 

 (1953), 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). Zooplankton volumes 

 (including ichthyoplankton) of samples collected in 1959 are 

 listed in Thrailkill (1963) and presented graphically in Smith 

 (1971) . 



Sorting involved the removal of ichthyoplankton from the 

 sample and identification and separation of eggs and larvae of 

 selected species (see introduction) . Usually, each sample was 

 sorted completely; however, some of the samples were fractioned 

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



^Blackburn, M. Preliminary cruise report of CalCOFI Cruise 

 5908-M. 



