FISHERY BULLETIN: VOL. 85, NO. 3 



cept Station 12, were not statistically different 

 from growth measured within the dense patch 

 (Station 37). Larvae collected at adjacent Stations 

 6 and 12, located to the northeast of the densest 

 area (Fig. 2), exhibited the lowest growth rates 

 and were not statistically different from each 

 other. 



Estimated age-at-length data from all stations 

 were combined to describe early growth in 

 walleye pollock from the Shelikof Strait region as 

 follows: 



SL = 4.29 + 0.21 (age, d) n = 109, r^ = 0.75 



where SL = standard length (Fig. 13). This rela- 

 tionship suggests a mean growth rate of 0.21 mm/ 

 day and an intercept of 4.29 mm, which corre- 

 sponds with the known size of newly hatched 

 larvae (Walline 1983; Nishimura and Yamada 

 1984). 



The distribution of dates of hatching was esti- 

 mated by back-calculating from the ages deter- 

 mined for larval walleye pollock in the Shelikof 

 Strait. The median birthdates from all stations 

 were similar and thus all 109 samples were com- 

 bined (Fig. 14). The hatching period ranged from 

 early April to mid-May with a mode in the last 



15 r 



10 



T3 

 C 



10 



20 



30 



40 



50 



Age (days) 



Figure 13. — Estimated age at length, fitted with hnear regression, for all 

 walleye pollock larvae analyzed from the northern Gulf of Alaska, May 1983. 



lOr 



o 



n 



10 



15 20 

 April 



25 



30 



10 

  May 



15 



20 



Hatching date 



Figure 14. — Distribution of hatching dates for walleye pollock determined by back- 

 calculation using age and date of collection. 



516 



