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Fishery Bulletin 104(3) 



a strong coastal branch of the Oyashio Current in the 

 Tohoku area. 



Early growth of walleye pollock 



There was no difference in SGR between Funka Bay and 

 northern Tohoku in 1999 ([/-test, P=0.111, Fig. 4). Also, 

 no regional differences were found among all regions in 

 2001 (ANOVA. P= 0.5261. For 2000, however, there were 

 significant differences in SGR among all four regions 

 (ANOVA, P<0.0001) and even between all pairs (Schef- 

 fe's test, P<0.0001). 



In 2000, the SOR 30 values ranged from 30-58 fjm 

 for the juveniles collected in Funka Bay and east of 

 Tsugaru Strait (Fig, 5). However, two different SOR 

 30 groups were found for the samples from northern 

 and southern Tohoku ([/-test, P<0.0001): one with SOR 

 30 values ranging from 30-60 ^tm and the other with 

 values greater than 68 fim. Fish of the former group 

 (low-growth group) had the same SOR 30 range as those 

 from Funka Bay and east of Tsugaru Strait. The latter 

 group (high-growth group) was observed only in the 

 Tohoku area. Positive linear regressions were found in 

 size-at-age relationships for low- and high-growth groups 

 (P<0.0001, Fig. 6) and the difference of the SGR was sig- 

 nificant between these two groups ([/-test, P<0.0001). 



These results indicate that the surveys of juvenile 

 walleye pollock in May 2000 caught two growth groups: 



