Itoh et al.: Migration patterns of Thunnus orientalis determined with archival tags 



525 



130°E 



140° E 



40°N 



30°N 



Figure 7 (continued) 



10898 



Figure 8 



Track of a young Pacific bluefin tuna that traversed the Pacific Ocean, estimated with an archival tag. "Rel" and "Rec" mean release and 

 recapture, respectively. Numerals are dates in ddnimyy. 



The second question is whether the water temperature 

 at the onset or end of traveling was within the temperature 

 range of 14— 20°C, considered to be in the temperature range 

 preferred by young Pacific bluefin tuna (Itoh et al., 2003). If 

 the act of traveling was simply a reaction to the water tem- 

 perature, fish would be expected to travel from water with a 

 temperature out of that range to one within that range. How- 

 ever that was observed in only two of 12 cases (Table 3). 



The third question was whether the temperature at the 

 end of traveling was a temperature that the fish encoun- 

 tered for the first time since the onset of traveling. We 

 found, however, that there was no specific trend in water 

 temperatures during traveling phases (Fig. 11). Six of 12 

 temperatures at the ends of traveling phases were not the 

 first one that the fish had experienced during the phase 

 (Table 3). 



