FISHERY BULLETIN: VOL. 70. NO. 3 



conducted during the sardine spawning season, 

 but excluded an important portion of the an- 

 chovy spawning season. Similarly, the cruises 

 only sampled 20% of the area we now consider 

 routinely surveyed. The ratio of sardine and 

 anchovy larvae was used for 1950 and will not 

 be discussed further. The 1969 samples system- 

 atically violated the assumption of stable size 

 composition of larvae. 



The cruises of 1940 and 1941 were conducted 

 over the southern California inshore and offshore 

 regions in the spring and sumimer. The total for 

 both species in both regions and in both years 

 was derived by simulation of analogous cruises 

 within the 1951-60 survey period and the pro- 

 duct-moment correlation coefficient is listed for 

 each species, for each region, and year. 



The ratio of this group of samples, within the 

 same boundaries as the other regional census 

 estimates used here, change from 1.70 to 3.64 

 in 1940 and change from 1.68 to 2.87 in 1941. 

 Accordingly, these ratios are used in Table 12. 

 The 1969 data point for anchovy is modified 

 in a crude attempt to adjust for the extra reten- 

 tion of anchovy larvae in a new sampling net 

 (see Figure 4) which retains approximately 50% 

 more larvae. The 1969 surveys were conducted 

 with a 1-m net with 50% more open area, more 

 regular mesh apertures, and an average mesh 

 width of 0.505 mm rather than the 0.55 mm 

 aperture silk net (used and wet). The effect 

 of additional mesh on reducing the extrusion 

 effect of filtration pressure is discussed in Trant- 

 er and Smith (1968). 



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500,000 



200,000 



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10,000 



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-2,000,000 



1,000,000 



- 500,000 



- 200,000 



- 100,000 



- 50,000 



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Figure 13. — A time-series comparison of sardine and 

 anchovy biomass estimates from 1940 through 1969. The 

 solid circle represents sardine biomass as calculated from 

 the fishery by Murphy (1966) and extends from 1940 

 to 1959. The solid triangle represents sardine biomass 

 derived from a regression estimate of the relationship 

 between the Murphy biomass estimate and the annual 

 total regional census estimate of sardine larvae during 

 the reference years and is extended from 1951 through 

 1969. The open circle represents the estimates of bio- 

 mass derived from the ratio of anchovy larvae to sar- 

 dine larvae and the Murphy sardine biomass estimate 

 from 1940 to 1959. The open triangle represents an- 

 chovy biomass derived from a regression estimate of 

 the relationship between the anchovy tonnage calculated 

 from the anchovy: sardine larvae ratio, and the annual 

 total regional census estimate of anchovy larvae and ex- 

 tends from 1951 through 1969. The open squares rep- 

 resent the Murphy estimate of anchovy spawning bio- 

 mass by 3-year averages (Murphy, 1966, Figure 17, p. 

 65). Dashed lines represent interpolations between non- 

 adjacent years. 



872 



