SMITH: SPAWNING BIOMASS OF NORTHERN ANCHOVY 



port with the wind-driven layer of the ocean 

 (Sette, 1943). While the entire problem of 

 transport is beyond the scope of this paper, a 

 comtDarison of size frequencies of larvae in the 

 southern California inshore, offshore, and sea- 

 ward regions shows a disproportionately lower 

 number of younger larvae in samples from farth- 

 er offshore (Figures 6 and 7). The most likely 

 explanation of these data is that older larvae 

 transported to the offshore regions are present 

 in excess of the numbers that have been spawned 

 and hatched there. Further, this implies that 

 the larva size frequency slope in the spawning 

 area is biased for the same reason. If the usual 

 sampling grid encloses the spawning area and the 

 areas to which larvae are transported no overall 

 bias should ensue. 



The MacGregor estimate of anchovy and sar- 

 dine biomass cited above, mentioned specific 

 numbers of spawnings per year and sex ratios. 

 Neither of these has been suitably evaluated as 

 yet. At present, there is no way of calculating 

 the number of batches spawned per year. In 

 this paper, I assume that the anchovy is twice 

 as fecund as sardine. An attempt will be made 

 to evaluate the sensitivity to multiple spawning 

 by proposing three spawning models, below. The 

 sex ratio is presently derived from the fishery 

 which is conducted over a very small proportion 

 of the anchovy range. Since males are somewhat 

 smaller, they may be expected to be recruited to 



g^ 



8 9 10 



LENGTH (mm ) 



Figure 7. — The size frequency of anchovy larvae cap- 

 tured in 1951-60 in the southern California inshore (clear 

 dot, solid line), offshore (black dot, small dash), and 

 seaward (triangle, large dash) regions. The size fre- 

 quency effect is attributed to offshore transport (see 

 text) . 



the fishery somewhat later than females. In 

 this report, the simple assumption of equality 

 of biomass will be maintained. This will tend 

 to overestimate the adult biomass by the degree 

 in which the male biomass is overestimated. 



Table 8. — Sample size frequency distribution for sardine and anchovy. 



surface. 



Total larvae per 10 m^ sea 



861 



