FISHERY BULLETIN: VOL. 70, NO. 3 



annual total (Ahlstrom, 1966, Table 8; 1968, 

 Table 3). 



a = 10^ 



q=i 





E 



«=i 



foi-^ br^ a dij 



n' 



(3) 



Murphy (1966) used the monthly version of 

 Ahlstrom's standard haul summation (Table 1) . 



The method used here is called the "regional 

 census estimate" 



Cm = 10 Arm-^ 



V^Oi-^ br' a di\ 



(4) 



where Cm = estimate of abundance of larvae in 

 region "r" in each quarter 

 Ar = Area of region "r" in numbers of 

 10 m^ areas. 



This method of assembly combines the sim- 

 plicity of the "standard haul summation" and 

 the areal weighting of the previously used census 

 estimates. The regional census estimate con- 

 sists of the mean number of larvae per standard 

 area (10 m^ sea surface) of all stations taken 

 within a region for a quarter of the year times 

 the number of standard areas within the region. 

 The same 183 stations or nearby alternates were 

 used within the routinely occupied area as de- 

 fined by Smith, Ahlstrom, and Casey (1970, Fig- 

 ure 1). The selected stations and acceptable al- 

 ternates are listed in Table 2 and the regions are 

 illustrated in Figure 2 and defined by area and 

 area factor in Table 3. 



The 1940 and 1941 stations have been assigned 

 to the two southern California regions (Table 4) 

 in which these cruises were conducted. The 

 number of stations per unit area has been held 

 nearly constant by the elimination of excess 

 stations in the early cruises. The 1949 station 

 equivalents are listed in Table 5. From 1950 to 

 1972 stations have been standard in placement. 



Table 5. — Equivalent station list for the CalCOFI survey 

 pattern for 1949 and 1950-72. 



Area 



Station no. 



used in 



1949 



Nearest 



present 



station no. 



Extra cruises, additional lines, and stations on 

 lines have been added periodically, resulting in 

 some increase in station density in some areas. 

 To stabilize sampling eflfort and remove possible 

 effects of added effort nearshore, all but 183 

 stations and their nearby equivalents have been 

 eliminated from further consideration for the 

 16-year compilation of regional census estimates. 

 The number of stations eliminated each year are 

 summarized in Table 6. 



856 



