FISHERY BULLETIN: VOL. 73, NO. 2 



125° W 



I2(rw 



II9*W 



125° W 



I20*W 



I5°N 



y*  



IO°N 



5°N 



125' W 



5°S 



II5°W 



Figure 23.-Day standing stock of skipjack forage (ml/ 1,000 m') 

 (combined Part I and II data), cruises Jordan bl-Cromwell 51, 

 November-December 1970. 



zones about 2° of latitude wide. There is no 

 difference in the significance of coefficients 

 depending on whether forage or forage x 

 zooplankton was the variable, and no significant 

 coefficients are obtained with zooplankton alone. 



Table 13 gives the data that yielded the sig- 

 nificant correlations between large skipjack and 

 forage. The correlation coefficients are +0.947 

 with catch per line-hour and + 0.886 with number 

 of schools per hour, significant at the 0.5 and 2.0% 

 probability levels respectively. The corresponding 

 Spearman rank correlation coefficients are + 0.952 

 and +0.905, both significant at the 5% level. No 

 other grouping of 2°-latitude zones would have 



IS'N. 



■lb°N 



I0°N 



125' W 



IZO'W 



Figure 24.-Night standing stock of skipjack forage (ml/ 1,000 

 m') (combined Part I and II data), cruises Jordan bl-Cromwell 51, 

 November-December 1970. 



given so many zones with so much data in each (see 

 Figure 3). 



The significance of the four correlation 

 coefficients in Table 12 has been disputed because 

 of the much larger number of nonsignificant 

 correlations in Tables 11 and 12 combined. It has 

 also been pointed out that the two coefficients in- 

 volving forage x zooplankton are not independent 

 of the two coefficients involving forage alone. In 

 our following comments we ignore all coefficients 

 with forage x zooplankton, whether apparently 

 significant or otherwise. We then have two possi- 

 bly significant coefficients in a total of 80 for Ta- 

 bles 11 and 12, i.e., one in 40. From the previous 

 paragraph, there is a chance of about one in 50 that 



400 



