58 



FISHERY BULLETIN OF THE FISH AND WILDLIFE SERVICE 



tn 



5 

 < 

 or 

 o 



UJ 



3 



o 



1500 



SO 60 70 80 



FISH WEIGHT IN KILOGRAMS 



Figuke 6.— Ovary weight-fish relation for yeUowfin tuna with ovaries in stages A and F. The lower curve represents 

 fish with ovaries in the immature, or resting, stage (A), and the upper curve represents fish with ovaries in a matur- 

 ing stage (F). An x indicates an individual with ovaries in a maturing stage other than F; a circle indicates a fish 

 which has spawned during the season. 



(table 5). There was a significant difference in 

 the level of the line representing stages B and C 

 from that representing stage A (F= 13.73; 

 P<0.01), but the mean difference of the observed 

 ovary weights was only 61.7 grams. Because of 

 the significant difference in the levels of the two 

 lines and because there were only eight ovaries in 

 stage B and four in stage C, these were excluded 

 from the linear regression of ovary weight on fish 

 weight for the immature stage. The plotted data 

 for stage A, shown in figure 6, were found to be 

 best fitted by the equation 



T=6.0929X- 124.35 

 where T is ovary weight in grams and X is fish 

 weight in kilograms. The dashed lines drawn 

 parallel to the regression line represent plus and 



minus twice the standard deviation from regres- 

 sion. 



Table 5. — Tests of significance among adjusted means 

 and between the regression coefficients of ovaries in 

 stage A and in stages B and G 



Source of variation 



Total deviations from pooled linear regres- 

 sion -. 



Deviations from average regression with- 

 in samples 



Deviations from individual regressions... 



Difference between regressions 



Difference between adjusted means 



Degrees 

 of free- 

 dom 



Sum of 

 squares 



123.99SS8 



98. 85509 

 94. 74937 

 4. 10572 

 25. 14379 



Mean 

 square 



1. 83065 



1. 78772 



4. 10572 



1 25. 14379 



1 Highly significant. 



As noted previously, there is an obvious increase 

 in ovary weight as the ova develop to the maturing 



