Distribution and Abundanceof Sardine and Anchovy Larvae 

 in the California Current Region off California and 

 Baja California, 1951-64: A Summary 



By 



ELBERT H. AHLSTROM 



Fishery Biologist (Supervisory) 

 Bureau of Commercial Fisheries California Current Resources Laboratory 



La Jolla, Calif. 92037 



ABSTRACT 



Data summarized in this report document the nine-fold increase in the 

 anchovy population (based on numbers of larvae) between 1951 and 1964, as well 

 as the marked decline in the distribution and abundance of sardine larvae. Data for the 

 years 1958-64 are treated in more detail than those for earlier years. Information 

 was obtained on cooperative hydrographic-biological cruises of the California Coop- 

 erative Oceanic Fisheries Investigations. 



INTRODUCTION 



This report summarizes infornnation about 

 larvae of the Pacific sardine, Sardinops 

 caerulea , and northern anchovy, Engraulis 

 nnordax , collected on survey cruises of the 

 California Cooperative Oceanic Fisheries In- 

 vestigations (CalCOFI), in 1 95 1 - 64. These data 

 record the spectacular increase in abundance 

 of the larvae of anchovy and the decrease 

 in numbers of those of sardine. The 

 CalCOFI surveys began in 1949, but the sur- 

 veys of 1949 and 1950 were less inclusive than 

 those made subsequently; hence they are not 

 strictly comparable. Data from these two 

 years are not included. 



The CalCOFI surveys during the decade of 

 the 1950's covered the waters off California 

 and Baja California, from Point St. George to 

 below Cape San Lucas (station lines 40 to 

 157), a north- south extent of 1,400 miles 

 (fig. I ). Seaward extension of lines was usually 

 between 150 and 300 miles. 



The pivotal station in laying out the CalCOFI 

 grid pattern was one about 40 miles offshore 

 from Point Conception, subsequently nunnbered 

 80.60. The coordinates of this station are lat. 

 340 09'N. and long. 121© 09'W. A base line 

 through this point, parallel to the general 

 trend of the coastline, has a true bearing of 

 330°. This base line was used to derive the 

 pivotal station line (line 80), which was oriented 



at right angles to it on a mercator projection. 

 Station lines are parallel to each other and 

 generally spaced 40 miles apart in the Cal- 

 COFI grid. 



Within the area between Point St. George 

 and Cape San Lucas are 36 station lines 

 spaced 40 miles apart. These consist of car- 

 dinal lines (those whose numerical designa- 

 tions end in 0, as 40, 50. ..150) and ordinal 

 lines (43, 47, 53, 57... 153, 157). Numbers 

 given to stations spaced along station lines 

 increase seaward by the amount of one \init 

 for each 4 miles of distance. 



The key station on each line as regards 

 numbering is station 60, which is located at 

 the point where the base line (line drawn 

 through pivotal station 80.60 with a true 

 bearing of 330°) intersects the station line. 

 In numbering a station, the line number is 

 given first, followed by a period and the sta- 

 tion number, as 80.60. 



During the period of monthly cruises (1949- 

 60), the numerical designation given to a cruise 

 was a combination of the year and month, as 

 5101 for the January cruise of 1951. This 

 simplicity of numbering was seldom possible 

 during the period of quarterly cruises (1961- 

 64), for the reason that most cruises required 

 longer than one month to complete. The num- 

 bering of quarterly cruises takes cognizance 

 of this; cruise 6101-02 was made in January 

 and February of 1961, for example. 



