FECTJNDITi' OF THE PACIFIC SARDINE 



435 



Table 4. — Comparison of regression coefficien ts 



RELATION BETWEEN FECUNDITY AND 

 WEIGHT 



The fish used for this fecundity study had 

 originally been preserved in formalin, but many of 

 them were subsequently transferred to alcohol. 

 The fish in alcohol were noticeably diiTerent in 

 appearance from those in formalin. The sub- 

 cutaneous fat deposits of the formalin preserved 

 fish showed through the skin and scales as a white 

 background wherever pigment did not conceal 

 them. These fat deposits were not apparent in 

 the alcohol preserved fish. The formalin pre- 



served fish also weighed considerably more than 

 alcohol preserved fish of comparable lengths from 

 the same sample. 



Only a few fish from sample SP-1 1 were in a jar 

 containing alcohol, and of tliese only one was a 

 female for which ovum counts were made. The 

 weights of the other 40 females for which ovum 

 counts were made are plotted in figure 7 as the 

 independent variable, with numbers of ova as the 

 dependent variable. Two different regression 

 lines have been fitted to the data. 



As will be shown for this sample, the weight ' of 

 a sardine is a much better indicator of its fecundity 

 than is its length. It can also be shown that for 

 practical purposes the F-intercept can be taken as 

 zero in the fecundity-weight regression without 

 any significant loss of accuracy (table 5). 



Table 5. — Comparison of two fecundity-weight regressiotis 



The use of the formula Y=bX enables one to 

 determine directly the total weight of spawning 



' The weight used is round weight. If the ovary weight is subtracted from 

 the round weight, the regression is not changed significantly (a = 4-3.3, 6 = 0.25, 

 S,=5.1, r=0.60). 



180 190 200 210 220 230 



STANDARD LENGTH IN MILLIMETERS 



Figure 6. — Fecundity-length regression Y—a + bX. 



240 250 



4:;tiUi ()_,i7_ 



