538 



Fishery Bulletin 101(3) 



B 10 



a. 



a 90% 



15 20 25 10 



0% 90% 90% 



50 



100 



15 



20 



25 



90% 



September 



10 15 20 25 10 15 20 25 



Temperature (°C) 



90% 



50 



100 



10 

 90% 



10 



0% 



90% 



May 



25 

 90% 



15 



20 



25 



Figure 2 



Vertical occurrence frequencies of young Pacific bluefin tuna in daytime (clear barl and nighttime (shaded bar) and 

 vertical thermal profile (line with dots) by month. 



120 -> 



Time (minutes) 



100 



120 



Figure 3 



Average swimming depth of young Pacific bluefin tuna recorded by archival tags at dawn (left panel) and 

 dusk (right panel). Times marked as are the time just after the end of rapid ascent at dawn and just before 

 the onset of rapid descent at dusk. All of records in which a rapid ascent or rapid descent occurred were 

 averaged. Bar shows standard deviation. 



the East China Sea, the area considered was enclosed by 

 four points of 29°N-126°E, 29°N-128°E, 35°N-130°E, and 

 33°N-126°E, where the majority of estimated tag locations 



occurred. The temperature range in each area was derived 

 from the sea-surface temperature maps published by the 

 Japan Fisheries Information Service Center. 



