encompassed the vertical distribution of sardine eggs and larvae. 

 Wide-ranging joint biological and oceanographic survey cruises 

 were resumed in 1949 with sardine as the focus; however, an 

 increasing interest in other biological components resulted in 

 the deepening of standard tows to 140 m in 1951. This marked the 

 beginning of truly guantitative ichthyoplankton sampling on 

 CalCOFI surveys. 



Data resulting from CalCOFI surveys in 1951 have been 

 published in a number of forms. Hydrographic data (Reid et al . , 

 1963), zooplankton volumes (Staff, SPFI, 1952; Thrailkill, 1956; 

 Smith, 1971) and ichthyoplankton data for selected species 

 (Ahlstrom, 1953) were presented in standard formats. The latter 

 lists counts for eggs and larvae of sardine and for larvae of 

 northern anchovy (Engraulis mordax) , jack mackerel {Trachurus 

 symmetricus) , Pacific mackerel {Scomber japonicus) , Pacific hake 

 (Merluccius productus) , and rockfishes (Sebastes spp.). Also, 

 length freguencies are listed for sardine and anchovy larvae. 

 Distribution maps of larvae of 5 of these species taken on 

 CalCOFI surveys during 1951 are presented in the CalCOFI Atlas 

 series (Kramer and Ahlstrom, 1968; Ahlstrom, 1969; Kramer, 1970; 

 Ahlstrom et al., 1978). 



A computer data base for eggs and larvae of sardine and 

 anchovy and for larvae of hake, and the two mackerels was 

 established in 1969. The development of a data base for other 

 fish larvae is a complex undertaking because competency of 

 identification has evolved steadily over the past 38 years. We 

 began the task of producing a CalCOFI ichthyoplankton data base 

 and associated data report series in 1983. All available 

 original records for 1951 were subjected to an extensive 

 verification and editing process to produce this report. This 

 and subseguent reports make the CalCOFI ichthyoplankton and 

 station data available to all investigators and serve as guides 

 to the computer data base. The data base will be modified when 

 additional errors are discovered and when composite taxa from the 

 earlier years are reidentif ied. These reports are the 

 fundamental reference documents against which subsequent changes 

 in the data base can be compared. 



SAMPLING AREA AND PATTERN 



In 1951, CalCOFI survey cruises were conducted at monthly 

 intervals. A total of 1368 stations were occupied on 12 

 cruises, with an average of 120 stations per cruise (range of 65- 

 170) . Coverage of the survey station pattern varied among 

 cruises and the entire quarter-million square mile survey area 

 was not covered on any single cruise (Figures 1-13; Table 1) . 

 The area off northern California (lines 40-57) was covered on 

 only two cruises made in July and August. Coverage off central 

 California (lines 60-77) was more consistent with stations 

 occupied monthly, except during February and March. The area 

 between Pt. Conception, California and Pt. San Juanico, Baja 

 California (lines 80-137) was surveyed monthly, except for 



