FECUNDITT OF THE PACIFIC SARDINE 



431 



.MATiRiNti (Transparent Eggs) 



Stage I: Frctiucncies with the lust iiiodf lictwocn 0.84 uiid 



0.04 mm. 

 Stago J: Frequencies with tlic lust mode above 0.94 mm. 



Mature (Transparent EIggs Free in- the OviDtCT) 



Stage K: Freqiienoies with the hi.st mode above 0.!)4 mm. 

 and the ripe eggs segregated. 



Spent 



Stage L: Frequencies with ova hirger tlian 0.20, but these 

 eggs degenerating. 



The numlxT of ova ii) the most advanced group 

 was calcidated by multiplying the weight of the 

 ovaries by the number of these ova in both 

 samples and dividing by tlie total weight of 

 both samples. It was also determined from each 

 of the two samples separately as a check on the 

 sampling variation. 



All (587) of the female sardines in the 13 samples 

 were used for ovum diameter measurements. 

 Ovum counts were made for all fisli (116) that 

 contained a distinct group of developing ova. 

 The weight of both samples from a pair of ovaries 

 equalled approximately 2 percent of the weight 

 of that pair of ovaries. The deviations of the 



116 pairs of ovinn estinuites from their respective 

 combined (>stimates was 1,700 eggs at one stand- 

 ard deviation level. The right and left ovaries 

 of each pair were at the same stage of maturity 

 in every case, and neither ovary gave a consist- 

 ently higher or lower count than the other. 

 As pointed out by Clark (1934), there are no 

 apparent differences in the relative immbers of 

 ova in eacii size group in the different parts of 

 the ovary. 



RELATION BETWEEN FECUNDITY AND 

 LENGTH 



Figure 3 shows 116 fecundity observations 

 obtained from the January and February, 1946, 

 samples plotted against their respective fish 

 lengths. The regression line, fitted by the method 

 of least squares, of the form Y=a-\-bX (where 

 Y=tlie number of ova in the most advanced 

 mode in thousands, A''=the fish length in milli- 

 meters and a and b are constants) is also shown. 

 Clark's (1934) 8 observations are plotted for 

 comparison. It is apparent from figure 1 that 

 the fecundity of individual fish of the same 

 length can vary considerably. This variation 



^vr- 



_L 



_L 



_L 



_L 



_L 



_L 



_L 



J_ 



170 180 190 200 210 220 230 240 



STANDARD LENGTH IN MILLIMETERS 



250 



260 270 



Figure 3. — Rehitioii between fecundity and standard length for IIG sardines (San Pedro, Jan. -Feb., 1946). Open circles 



are Chirk's (19:54) observations. 



