FECUNDITY OF THE PACIFIC SARDINE 



439 



180 190 200 210 220 230 

 STANDARD LENGTH IN MILLIMETERS 

 Figure 10. — Regression line y=0.51-lA' — 76.0 adjusted for various K values by formula deviation = . 372X^ — 47.9. 



In figure 10 are plotted the regression lines of 

 fecundity-length for tlie 116 sardines adjusted for 

 various K values on the basis of the computed 

 deviation values owing to K (weight correction) 

 found in sample SP-11. On the basis of this 

 figure it can be seen that a 20-unit K value differ- 

 ence between two groups of sardines of similar 

 length distribution would result in a difference of 

 7.4 thousands of ova in tlie most advanced grouj) 

 of developing ovarian ova for each fish. Tlie 

 above is, of course, purely theoretical when applied 

 to years other than 1946. Sample SP-11 is prob- 

 ably representative of the population present in 

 the San Pedro area in January and February of 

 1946 with respect to K. The mean K value of 

 sample SP-11 (taken on Feb. 9, 1946) is 128.6. 

 The approximate mean K value obtained from 

 thirty-four Sfl-fish samj)los from the San Pedro 

 commercial fisiiery in January and February of 

 1946 is 128.1. What actually happens in years 

 of very high or very low K values of the Pacific 



sardine may be very different from what can be 

 postulated to happen on the basis of fecundity 

 values extrapolated to these high or low K values. 

 The pre-spawning-season condition of a fish may 

 determine not only how many ova will develop 

 per batch of developing ova, but also how many 

 batches will spawn, or if spawning, will take place 

 at all in that season. 



RELATION BETWEEN FECUNDITY AND 

 AGE 



The mean lengths of each age group arc com- 

 pared with those obtained by Phillips (1948) for 

 the 1945-46 commercial sardine fishing season at 

 San Pedro in table 8. The sampling method upon 

 which Phillips' data are based was designed to 

 sample the commercial catch representatively 

 throughout tlie fishing season. Although he used 

 fewer fish, a much larger nimtber of samples are 

 included in his data. 



