10 



9 - 



FOOD OF BIGEYE AND YELLOWFIN TUNA 

 YELLOWFIN BIGEYE 



65 



T 



T 



T 



T 



(A) 



^ :■■■■■■ -f • • -i-:- 



(B) 



"1 r 



"1 r 



(B) - 



40 



280 



320 



360 



80 120 160 200 240 40 80 120 160 200 240 



BODY WEIGHT (LBS) BODY WEIGHT (LBS) 



Figure 4. — Regressions of (A) food volume per stoniacli and (B) food volume per unit body weight on total body weight 



for 439 yellowfin and 166 bigeye captured on longlines. 



and tliere is also a decrease in average stomaeli 

 content per unit of body weight (cc./lb.) with 

 increase in size of fish. Tlie least-s(itiares trend 

 lines shown in figure 4 (tliere is no a priori reason 

 for assuming rectilinearity) indicate tlH> need for 

 covaiiance nu'thods of statistical analysis, again 

 after stiitahie liansformations. Finally we must 

 point out the great variability of the data as 

 illustrated by the wide scatter of points about tiie 

 trend lines. This gi-eat variability reduces the 

 opportunity- of denionstrMting stat ist icidly signifi- 



cant differences, particularly when the data are 

 analyzed in subgroups which contain few speci- 

 mens in each. 



Because of the difficidties outlined above, in the 

 following sections we have tabulated average 

 values and have discussed difi'crences and trends 

 without attempting to ajjpraisc their statistical 

 significance. Consequently, the inferences that 

 we make must be regarded as suggestions oidy. 

 They may form the bases for hypotheses which can 

 be tested more stringently in the futuic. 



