FISHERY BULLETIN: VOL. 82, NO. 1 



1980B 



1980C 



1981B 



40 60 20 



AGE (DAYS) 



Fic.i'RE 1.— Mean (± 1 SD) live standard length at age posthatch for 

 seven groups of Pacific herring larvae. See Table 2 for the regres- 

 sion equations. 



from yolk-sac larvae was a single sample from 1980D 

 that had a mean (± 1 SD) ring count of 5.2 ± 0.8 (n = 

 9) on day 1 posthatch. The rings were not observed in 

 older, larger larvae; they may have been present but 

 obscured by overburden over the nucleus. This 

 phenomenon has been observed in the otoliths of lar- 

 val largemouth bass, Micropterus salmoides, (Miller 

 and Storck 1982). A group of 7-8 "prolarval rings" 

 that were clustered about the nucleus at swim-up 

 were visible for only 10-15 d afterward, because the 

 nucleus became more opaque with age. 



The first normal ring was deposited in all groups 

 including 1980C by day 6 posthatch, the day after 

 complete yolk absorption. This agrees well with the 

 age at first increment of 4.5 (range = 0-9 d) found for 

 Atlantic herring by Lough et al. (1982) and with the 

 age of 6 d found for the same species by Geffen 

 (1982). This indicates that herring larvae of both 

 species do have a fixed age at first increment deposi- 

 tion and that it coincides with the age at complete 

 yolk absorption. 



Rates of subsequent ring deposition for the four fed 



40 60 



AGE (DAYS) 



FIGURE 2.— Mean (±1 SD) ring count at age posthatch for seven 

 groups of Pacific herring larvae. Open circles are total rings and 

 closed circles are normal rings only. See Table 3 for the regres- 

 sion equations. 



groups were not all daily, and they ranged from 0.12 

 to 0.96 rings/d (Table 3); only two groups, 1980A and 

 198 IB, had rates that were not significantly different 

 from 1 ring/d (t = 0.5772, df = 3, 0.5 > P> 0.9 andt = 

 2.0142, df = 4, 0.10 > P > 0.20, respectively). The 

 1981A group had a rate that was significantly <1 

 ring/d (t = 6.3465, df=5, 0.01 >P> 0.001) butalso 

 significantly > (t = 10.8062, df = 5,P< 0.001) and 

 the 1982 A group had a rate that was significantly < 1 

 ring/d {t = 10.0228, df = 2, 0.01 > P> 0.001) andnot 

 significantly >0 (t = 1.3667, df = 2, 0.20 > P > 

 0.40). 

 The rate of ring deposition in 1980C, the group that 

 was starved from hatch, was —0.05 ring/d, which was 



Table 3. — Linear regressions of mean normal ring number on age in 

 7 groups of Pacific herring larvae. 



116 



