in good correspondence with the average sizes 

 of the fish (fig. 5) taken in these fisheries and 

 therefore suggests that, as outlined in figure 

 18, the North American to pole-and-line to long- 

 line route is more likely than the North Ameri- 

 ca to longline to pole-and-line route. 



Correlation Between Apparent Abmidances for 

 the Pole-and-line Fishery and for the Longline 

 Fishery 



A third line of evidence that bears on the 

 route of the albacore is that presented by Suda 

 (1958 and 1963b). First, he computed the cor- 

 relation between the apparent abundance for 

 each pole-and-line fishing season and the ap- 

 parent abundance for each subsequent longline 

 fishing season. Second, he computed the corre- 

 lation between the apparent abundance for each 

 pole-and-line fishing season and the apparent 

 abundance for each preceding longline fishing 

 season. He found a much higher correlation 

 coefficient between pole-and-line apparent 

 abundance and apparent abundance in the sub- 

 sequent longline season than that between the 

 pole-and-line apparent abundance and that of 

 the preceding longline season. This result 

 implies that the fish tend to move from the 

 pole-and-line fishery to the longline fishery, 

 rather than from the longline fishery to the 

 pole-and-line fishery. A few points of caution 

 should be mentioned, however, in considering 

 these correlations. First, rather few degrees 

 of freedom were available for computation of 

 the correlation coefficients. Secondly, an ex- 

 amination of the scatter diagrams (Suda, 1963b) 

 from which these correlations were computed 

 shows that the poor correlation between appar- 



ent abundance for the pole-and-line season and 

 the preceding longline season is generated, to a 

 large extent, by a single datum. We note, also, 

 that on the basis of the temporal occurrence of 

 the pole-and-line and longline fisheries that we 

 should a priori expect a higher correlation be- 

 tween the pole-and-line fishery and the preced- 

 ing longline fishery than between the pole-and- 

 line and subsequent longline fishery. This is 

 because the midpoint of the pole-and-line fish- 

 ery occurs only about 4 months after the mid- 

 point of the longline fishery, whereas the mid- 

 date of the longline fishery comes about 8 

 months after the middate of the pole-and-line 

 fishery. Our a priori expectations are, how- 

 ever, not borne out, and thus we give greater 

 weight to the interpretation that the predomi- 

 nant flow of albacore is from the pole-and-line 

 fishery to the longline fishery. 



Tagging Data 



The last line of evidence is based on the tag- 

 ging data presented in figure 16. We note from 

 figure 16 that of the 11 fish tagged in the North 

 American fishery 5 were recovered in the 

 longline fishery and 6 were recovered in the 

 pole-and-line fishery. Furthermore, we could 

 interpret the data on the tagged fish that was at 

 liberty 1,214 days to indicate that the fish 

 passed through the pole-and-line fishery before 

 entering the longline fishery. This assumption 

 would imply that the pole-and-line fishery 

 takes most fish that cross the Pacific at the 

 time of the tagging experiment. Of the four 

 fish tagged in midocean and recaptured, three 

 were recovered in the longline fishery and one 

 in the pole-and-line fishery. These recoveries 



• MIGRATION ROUTE FROM NORTH AMERICAN TO LONGLINE TO POLE AND LINE 



• MIGRATION ROUTE FROM NORTH AMERICAN TO POLE AND LINE TO LONGLINE 



65 CM, 



L NO 



NORTH 



74 CM. 



78 CM. 



ABOUT 

 5 MONTHS 



I 



ABOUT 

 4 MONTHS 



ABOUT 

 2 5 MONTHS 



iiliifc 



JAPAN 

 LONGLINE 



"T 



~T 



T 



JAPAN I NORTH 



I POLE AND line! AMERICAN 



ABOUT 

 8 MONTHS 



T 



85 CM. 



JAPAN 

 LONGLINE 



mwixmrnmism 



JUNE ' JULY ■ AUG. ' SEPT. OCT NOV. DEC. JAN. FEB. MAR. APR. MAY JUNE JULY AUG. SEPT OCT NOV. DEC. JAN. 



Figure 18. --Expected lengths of albacore taking two different migration routes. 



26 



