COMPARISON OF YELLOWFIN TUNA OF HAWAIIAN WATERS AND THE AMERICAN WEST COAST 357 



Table 1. — Morphometric measurements and counts for Yellowfin tuna (Xeothunnus macropterus) from the Hawaiian 



Islands Feb. 21-Sepl. 38, 1949— Continued 



1,611 mm. 

 1,614 mm. 

 1,621 mm. 

 1, '129 mm. 

 1,629 mm. 

 l,rai mm. 

 1,635 mm. 

 1 ,6;i6 mm . 



1.638 mm. 



1.639 mm. 



1.640 mm. 



1.641 mm. 



1.642 mm. 



1.643 mm. 

 l,i'48mm. 

 1,654 mm, 



1.659 mm. 



1.660 mm. 

 1,662 mm. 

 1,665 mm. 

 1,665 mm. 

 1,670 mm. 

 1,670 mm. 



1.673 mm., 



1.674 mm. 

 1,674 mm. 



1.676 mm. 



1.677 mm. 

 1,682 mm. 

 1,696 mm. 

 1,700 mm. 

 1,700 mm. 

 1,700 mm. 

 1,7113 mm. 

 1,703 mm. 

 1.705 mm. 

 1,714 mm. 



1.716 mm. 



1.717 mm. 



1.718 mm. 

 1,721 mm. 



1.723 mm. 



1.724 mm. 

 1,734 mm. 

 1,748 mm. 

 1,778 mm. 

 1,780 mm. 

 1,785 mm. 



Mm. 

 796 

 811 

 785 

 822 

 829 

 810 

 811 

 813 

 810 

 812 

 813 

 809 

 797 

 822 

 808 

 820 

 818 

 827 

 814 

 826 

 835 

 822 

 803 

 829 

 850 

 827 

 817 

 829 

 845 

 844 

 841 

 839 

 849 

 847 

 848 

 836 

 838 

 846 

 846 

 830 

 861 

 832 

 850 

 847 

 847 

 866 

 835 

 889 



M 

 M 



M 

 M 



M 

 M 

 M 



M 

 M 



M 



13 7+2 



8+1 

 8+2 

 8+1 

 8+2 

 8+2 

 8+1 

 8+1 



M 



M 



M 

 M 



M 



M 



M 



M 



M 

 M 

 M 

 M 



M 



m' 



M 

 M 

 M 



M 



M 



M  

 M 



M 



Godsil (1948), whose work will be discussed sub- 

 sequently, has fovmd that a curvilinear equation 

 fits the regressions on bodj^ length of the distances 

 from the tip of the snout to various fin insertions 

 and head length rather better than a linear one. 

 He also discovered that when he fitted regression 

 equations of the selected tj^pe to each of several 

 samples from the same region, and also fitted an 

 equation of this same type to the pooled data of all 

 such samples, the individual regressions differed 

 from the regression for the pooled data to a gi-eater 

 extent than might be expected from purely random 

 variation. This he attributed to a lack of "bio- 

 logical homogeneitj'" (which he contrasts to "sta- 

 tistical homogeneity") within the stock of fish 

 sampled, arising from incomplete mixing of fish 

 from different spa\vning gromids. This may in- 



deed be true. A rather simpler explanation is that 

 the small differences he found between regressions 

 among the samples from the same region are due to 

 rather great differences in size composition of the 

 several samples and the necessarilv approximate 

 nature of the regression equations employed. 

 "Whatever the cause, it is necessary to recognize 

 that such differences can and do arise and to take 

 suitable account of them where required, both in 

 the sampling and in the subsequent analysis. By 

 drawmg samples widely from many diff'erent 

 schools within the region to be studied, one muii- 

 mizes for purpose of comparison the effects, if any, 

 of lack of "biological homogeneity" by including in 

 the variance of the sample any differences between 

 subdivisions of the population with different 

 genetic histories. By comparing only samples of 



