FISHERY BULLETIN: VOL. 84, NO. 3 



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NO. ANNULI BACK-CALCULATED 



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Figure 2.— Relationship between extent of back-calculation from scales and the body length estimated 

 at 1 and 2 yr in Pacific herring from Auke Bay, AK. Points indicate the deviation of size estimates for 

 age-1 and age-2 Pacific herring from the average for all annuli (the second annulus was taken as the first 

 year's mark). 



(1979) data from the eastern Bering Sea had only 

 one stanza. Regardless of the data source, linear 

 regressions (Walford regressions) closely fit the data 

 in the growth stanzas (Tables 1, 2). 



The method of aging Pacific herring can influence 

 estimates of growth. In the data that I examined 

 for this study, adult stanzas based on back-calculated 

 lengths usually had lower slopes than adult stanzas 

 based on terminal-lengths-at age (Table 1). Further- 

 more, the plots of back-calculated data inflected 

 either at 2 yr or not at all, in contrast to plots of 

 lengths-at-terminal-age, which inflected at 3 yr in 

 three of six examples (Table 1). Important factors, 

 however, remain uncontrolled in this comparison. 

 For instance, the lengths-at-terminal-age from the 

 literature were based on summer sampling; hence, 

 they include additional growth after annulus 

 formation. The lengths-at-terminal-age were from 



populations near or on the open coast, which may 

 grow faster than populations from protected and 

 possibly less productive waters within the Alex- 

 ander Archipelago. Furthermore, it is not clear 

 that the Alaskan data for lengths-at-terminal-age 

 used the second scale annulus as the first year's 

 mark. 



Walford graphs for Pacific herring from Tomales 

 Bay, CA (data from Spratt 1981), and the eastern 

 Bering Sea (this study) indicated that juvenile 

 growth success and age at inflection (intersection 

 of juvenile and adult stanzas) are more important 

 determinants of adult size at age than either length 

 at year 1 or the slope of the adult stanza, the adult 

 growth proportion (Table 1; Fig. 3). The data in- 

 dicate that herring from the Bering Sea quickly 

 outgrow those from Tomales Bay although the BL's 

 of the two groups were almost identical at ages 1 



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