SMITH: SPAWNING BIOMASS OF NORTHERN ANCHOVY 



Table 2. — Continued. 



Murphy (1966) estimated the biomass of the 

 spawning stocks of sardine from 1932 to 1959. 

 He also compared the anchovy: sardine larval 

 ratio from 1951 to 1959 and graphically com- 

 pared this with the larval ratio over a portion 

 (about 20%) of their joint range in 1940 and 

 1941 (p. 65). The striking decline of the sardine, 

 and the increase of the anchovy biomass, has 

 stimulated speculation on the biological inter- 

 actions of these species and the MRC (Marine 

 Research Committee of California) has a stand- 

 ing recommendation that 200,000 tons of an- 

 chovies and 10,000 tons of sardines be harvested 

 in an experimental attempt to foster the recovery 

 of sardines. It is the primary goal of this rec- 

 ommendation to restore and maintain the bal- 

 ance of sardines and anchovies in the California 

 Current system by manipulation of fishing effort. 



The estimates of spawning biomass of the 

 northern anchovy have been based on the spawn- 

 ing biomass of the Pacific sardine as derived 

 from the fishery (Murphy, 1966; Ahlstrom, 

 1968) and on the assumed relationship between 

 sardine and anchovy fecundity, survival, and 

 escapement of larvae through the meshes of the 

 CalCOFI standard silk survey net (Lenarz, 

 1972). For convenience, the larva data for all 



estimates to date are listed in Table 1. A series 

 of stations oflP southern California was occupied 

 in 1940 and 1941, and the anchovy: sardine ra- 

 tios were 1.18 (13,962 anchovy to 11,862 sar- 

 dines) and 1.66 (12,560 anchovy to 7,564 sar- 

 dines) respectively. The 1940, 1941, 1949, and 

 1950 data will be referred to later in a section 

 on interaction of sardine and anchovy. 



METHOD OF DATA ASSEMBLY 



The method of assembling the estimates of 

 larval abundance for this paper differs from that 

 of Sette and Ahlstrom (1948) and Ahlstrom 

 (1954, 1966, 1967, 1968). Two methods of as- 

 sembly were used previously: the "census esti- 

 mate" and the "standard haul summation." In 

 the "census estimate" each larva sample count 

 was weighted by the area of a polygon formed 

 by construction of "perpendicular bisectors of 

 lines drawn from the station to each of all sur- 

 rounding stations" (Sette and Ahlstrom, 1948, 

 p. 521; Ahlstrom, 1968). 



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