Fang et al.: Age, growth, and population structure of Ommastrephes bartramn in the North Pacific Ocean 
39 
Figure 4 
Variation of instantaneous growth rate (G) and absolute daily growth rate (DGR) measured in (A) mantle 
length (ML) and (B) body weight (BW) for male (M) and female (F) red flying squid (Ommastrephes bar- 
tramii), and growth curves in relation to (C) ML and age, (D) BW and age, and (E) upper rostral length 
and age of red flying squid in this study. 
ranged from 150 to 250 g. The BW of males ranged 
from 210 to 1440 g (average=462 g [SD 225]); 92.7% of 
males ranged from 150 to 250 g (Fig. 3B). 
The estimated age, which was based on the micro- 
structure of upper beak RSS, ranged from 107 to 322 
d (mean age=203 d [SD 55]) for females. The dominant 
age for females ranged from 150 to 300 d — a range that 
accounted for 75.4% of the female samples. Estimated 
age ranged from 110 to 320 d ( mean age=180 d [SD 
45]) for males, and the dominant age, from 110 to 250 
d, which accounted for 92.2% of male samples (Fig. 3C). 
The back-calculated hatching time in this study ranged 
from October 2010 through June 2011. The peak hatch- 
ing time occurred from January through April for fe- 
males, accounting for 72.7% of female samples, and 
from February through April for males, accounting for 
74.7% of male samples (Fig. 3D). Most of the squid in 
this study hatched in late winter and early spring. 
Growth rate patterns 
Growth rate patterns were similar between ML and 
BW despite squid age (Table 1; Fig. 4, A and B). For 
female squids, the maximum DGR was 1.07 mm/d for 
