45t 



OVA DIAMETER (MM.) 



Figure 5. — Frequency distribution of egg diameters, used for defining the most advanced mode in the ovaries of a 



540- mm. skipjack tuna. 



Fork lengths and fecundities of 13 skipjack 

 tunas are shown in table 3. A straight line was 

 fitted to fork length versus fecundity by the 

 method of least squares. The equation de- 

 scribing the regression line is Y = -1333.541 

 + 3.238 X, where Y is the number of ova in 

 the most advanced mode in thousands and X 

 is the fork length of the fish in mm. The coef- 

 fient of correlation is 0.873 (P ^ 0.01, lld.f.). 

 The line and scatter diagram are shown in 

 figure 6, together with the data of Yabe (1954) 

 and Yoshida (1966), and the regression lines 

 of Raju (1964) and Joseph (1963). All data ap- 

 proximate my regression line except those 

 of Joseph, probably because of the small size 

 range of fish used in his determination. Al- 

 though I used a straight line in the figure to 

 facilitate comparison of my data with those 

 of the other workers, I obtained a slightly 

 better fit by using cube of the length versus 



fecundity (coefficient of correlation is 0.886, 

 11 d.f.)--as should be expected according to 

 MacGregor (1957). The few data do not war- 

 rant reporting a detailed analysis. 



NEMATODE INFESTATION OF 

 THE OVARIES 



The ovaries of about 90 percent of the mature 

 skipjack tuna examined in the present inves- 

 tigation were infested with nematodes, but 

 none were found in immature fish. The lumina 

 of a pair of ovaries had contained up to about 

 75 nematodes, but they did not cause noticeable 

 damage to the eggs. 



Yuen and June (1957) found nematodes in 

 the ovaries of yellowfin tuna from the Pacific, 

 but the parasites were too poorly preserved to 

 identify. 



14 



