FISHERY BULLETIN: VOL. 69. NO. I 



Table 2. — Hour of day that paired oblique plankton 

 hauls were taken from the four research vessels par- 

 ticipating in EASTROPAC I. (Midtime of haul used.) 



Hours of 

 day 



Number of hauls token during each hour of the day frorr 



Argo 



David Starr 

 Jordan 



Rockaway 



Alaminos 



All 



vessels 



number given to the offshore vessel. The three 

 digits following the period are numbers given 

 to observations made from each vessel during a 

 cruise, numbered sequentially. Not all "stations" 

 included obliqne plankton hauls; hence there are 

 gaps in numbers applied to plankton collections. 

 The locations of plankton stations occupied by 

 the four research vessels participating in 

 EASTROPAC I are showTi in Figure 1. Sam- 

 ples collected from the Argo are designated as 

 the 11.000 series, samples from the David Stan- 

 Jordan as 12.000 series, Rockaway samples as 

 13.000 series and Alaminos samples as 14.000 

 series. In tables to follow, the series of samples 

 taken by each vessel is designated by the above 

 identifying series numbers. The aggregate of 

 stations occupied by each vessel is referred to in 

 text discussions as its pattern. 



PROCESSING SAMPLES ASHORE 



As noted above, only samples from 1-m 

 oblique net hauls were sorted routinely for fish 

 eggs and larvae. As a rule the entire sample was 

 sorted; in fact only six collections out of 482 



were aliquoted — four collections were split into 

 50 ^r aliquots, two collections into 2.5 '^r aliquots. 



The author made all identifications and counts 

 of lan'ae from EASTROPAC I collections. Ac- 

 tual counts of larvae rather than standardized 

 values (see below) are used in tabulation 

 throughout this paper, except one (Table 7). 

 There are several reasons why I chose to do this. 

 As indicated previously, all hauls were made in 

 a roughly comparable fashion. In many studies 

 the investigator is interested in the presence or 

 absence of the larvae of a given species or as- 

 semblage of species as such relate to water 

 masses, community composition, time of day, etc. 

 Such information is most readily obtained from 

 records of actual counts. Some statistical tests 

 require the use of original counts rather than 

 standardized data. For persons interested in 

 deriving standardized counts comparable with 

 those employed for CalCOFI data (Ahlstrom, 

 1953), standard haul factors for the 482 oblique 

 hauls taken with the 1-m net on EASTROPAC I 

 are given in Appendix Table 7. 



Two major considerations in the quantitative 

 sampling of fish larvae for resources evaluation 

 are (1) how well has their depth range been 

 covered and (2) how effectively have the larvae 

 been sampled within this layer? 



We do not have direct answers to either of 

 these questions from EASTROPAC cruises. 

 No studies were made on depth distributions of 

 fish eggs and larvae in the EASTROPAC area. 

 As will appear, fewer fish larvae wei'e obtained 

 during daylight hours than in night hauls; how- 

 ever, we lack information on how completely 

 larvae were sampled in night hauls. 



DEPTH DISTRIBUTION OF FISH 

 LARVAE 



Although collecting methods used on EAS- 

 TROPAC did not permit a study of depth distri- 

 bution of fish larvae, such information for the 

 California Current region off California and 

 Baja California and in a less detailed way for 

 the NORPAC Expedition of 1955 are available 

 (Ahlstrom, 1959). 



In the California Current region, most fish 

 eggs and larvae were distributed within the up- 



