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Fishery Bulletin 105(3) 



1.0 



0.8 



0.6 



0.4 



A_^ OOP 



: /o 



O / 



0.6 



0.4 



0.2 



200 4011 600 800 I DUO 



Age (years) 



Figure 5 



The proportion of mature female Pacific cod (Gadiis macrocepha- 

 lus) by age in (A) the Gulf of Alaska, based on the January 1999 

 and 2004 (;7 = 154l collection and in (B) the Bering Sea, based 

 on the February 2003 (« = 129) collection. The mean age at 50'7f 

 maturity=4.4 (A) and 4.9 years (B), and the 95% confidence 

 intervals are represented by the parallel dotted lines. 



ost (Waiwood, 1982; Foucher and Tyler, 1990) and can 

 produce up to 5.7 million ova each year. However, it 

 appears that the metabolic costs of spawning do not 

 diminish female Pacific cod growth. 



Female Pacific cod growth does not significantly de- 

 cline upon reaching A^^ in either the Gulf of Alaska or 

 Bering Sea. Males in the Gulf of Alaska area reach a 

 smaller maximum length than females. Similarly, in 

 the eastern Sea of Okhotsk, male Pacific cod reach a 

 smaller total length than females (Rovnina et al., 1997). 

 In contrast male Pacific cod in the Bering Sea area 

 reach a maximum length similar to that of females, 

 and female Pacific cod grow significantly faster in the 

 Bering Sea than in the Gulf of Alaska. The growth 

 results support the maturity-at-length results in the 

 present study that indicate a much larger Lj, for the 

 Bering Sea females. Longevity, however, is similar for 

 Gulf of Alaska and Bering Sea Pacific cod and does 

 not differ between sexes. Pacific cod growth probably 



occurs primarily during the summer and fall, as does 

 growth in Atlantic cod (Norberg et al., 2004), and not 

 during the winter through early summer months, the 

 period used by the present study to assess length- and 

 age-at-maturity. 



With the estimates of Ag^ and Lj,^^ from this study, 

 the spawning stock biomass of female Pacific cod for 

 the Gulf of Alaska and eastern Bering Sea increased 

 from the 2005 estimate of 300x10'^ t that was based 

 on a previous study, to an 2006 estimate of 500x10^ t 

 (Thompson and Dorn, 2005; Thompson et al., 2005). 

 The spawning biomass estimates are of critical impor- 

 tance for stock management models from which are 

 determined the allowable commercial catch quotas of 

 Pacific cod in the northeast Pacific Ocean and Bering 

 Sea (Thompson and Dorn, 2005; Thompson et al., 2005). 

 The increased spawning stock biomass estimates of fe- 

 male Pacific cod resulting from this study support the 

 establishment of higher over-fishing limits for Pacific 



