WARNER: REPRODUCTIVE BIOLOGY OF PIMELOMETOPON PULCHRUM 



Further evidence for multiple spawning is seen 

 in the ovaries from some females captured in 

 August and early September. There were a few 

 mature eggs free in the lumen and numerous 

 empty follicles in the lamellae, both indications of 

 recent spawning. At the same time, another group 

 of vitellogenic oocytes were observed developing 

 in the lamellae and these would presumably have 

 been spawned at a later time. 



As Yamamoto and Yamazaki (1961) point out, 

 the presence of multiple spawning complicates 

 any determination of the number of eggs 

 produced each year by an individual fish. Es- 

 timates can be made from an analysis over time of 

 frequencies of egg diameters, such as that done by 

 Clark (1934) for Sardinops caerula. Such analyses 

 require a large sample over the mature size range 

 and this was not available for P. pulchrum. 



Counts of the yolky oocytes in subsamples of 

 ovaries made for California sheephead females 

 captured in July (Table 5) are probably overes- 

 timates of the number of eggs spawned during the 



Table 5.-Estimates of the total number of vitellogenic oocytes 

 and density of those oocytes in the ovaries of Pimelometopon 

 pulchrum captured at Catalina Island in July 1970. 



Standard Weight of 



length Date of ovary 

 (mm) capture (g) 



Estimated Estimated 



number of number of 



yoll<y oocytes, yolky oocytes 



total per gram of ovary 



5,250 

 4,450 

 4,650 

 6,125 

 5,125 

 5,930 

 5,750 

 4,920 

 6,200 



Mean and 95% confidence limits of oocyte density, oocytes per 

 gram = 5,377 ± 499. 



season. This is because, as pointed out above, the 

 relationship between the number of these oocytes 

 and the number actually spawned depends on the 

 survival rate of the oocytes to maturity and the 

 proportion that are actually ejected from the body. 

 The smaller numbers of stage 5 oocytes relative to 

 stages 3 and 4 (Figure 12) indicates a loss during 

 development. There are certainly some eggs left in 

 the lumen of postspawning females. These 

 degenerate and are presumably absorbed during 

 the resting phase. 



For an analysis of the functional significance of 

 sequential hermaphroditism, actual egg numbers 

 are less important than data on the relative values 

 for age- or size-specific fecundities (Williams 1966; 



Warner in press). As long as the number of eggs 

 per unit weight of ovary does not vary appreciably 

 with size or age, weights of active prespawning 

 ovaries can be used to represent relative fecundi- 

 ties. The last column of Table 5 shows there is no 

 apparent effect of fish length on egg density 

 within the ovary. 



Comparison of ovary weights and standard 

 lengths for mature females captured at Catalina 

 in June and July (Figure 13) shows that fecundity 

 increases exponentially with the length. The ex- 

 ponential equation: 



W = 1.31 X 10-^ L^^^ 



{W = gonad weight, L = standard length) in- 

 dicates that the increase of gonad weight with 



20 22 24 26 28 30 32 34 36 38 

 STANDARD LENGTH (cm) 



Figure 13.— Ovary weight versus standard length for females of 

 Pimelometopon pulchrum captured in June and July at Catalina 

 Island. 



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