Wespestad and Moksness: Growth and survival of Clupea pallasii 



195 



The length of newly hatched herring was normally 

 distributed with length ranging from 6 to 9 mm (Fig. 

 5a). The distribution of weight was skewed slightly, and 

 dry weight ranged from 91 to 300 ^g (Fig. 5b). 



The length at hatching of these larvae is similar to 

 that reported from other Pacific herring stocks: British 

 Columbia 4-8 mm (Stevenson 1962), 8.5-9 (Alderdice 

 and Hourston 1985); California 8 mm (Talbot and John- 

 son 1972.) 



The growth rate from hatching to experiment termi- 

 nation 63 days later averaged 0.66 mm/day and ranged 

 from 0.31 mm/day for the smallest to 1.48 mm/day for 

 the largest. Daily growth increased from 0.1 mm/day 

 on day-3 to 0.64 on day-21 and then decreased (Fig. 6a). 



A Gompertz growth curve 



L, 



,-k 



was fitted to the length-at-age data, where 



L^ = Length infinity 



k = Brody growth coefficient 



b = regression constant 



t = age in days. 



The resulting parameters were L^ = 202.3 mm (SD 

 86.34), k = 3.299 (SD 0.389), and 6 = 0.013 (SD 0.03). 

 The fit of observed length to the model is shown in 

 Figure 6b. The poor fit is due to the lack of observa- 



Length in mm 



0- -^ 



091 



Weight in milligrams 



Figure 5 



(A) Length-frequency and (B) weight frequency distribution at hatch- 

 ing of Pacific herring larvae from Bristol Bay, Alaska. 



tions beyond the inflection point. Based on the length 

 of age-0 herring captured in the Bering Sea in Sep- 

 tember, L^ should be between 80 and 90 mm and A- 

 proportionately lower. 



Weight-at-age was more variable than length-at-age 

 (Fig. 6c). Average weight increased in weight from 0.19 

 mg at hatching to 182 mg on day-63, or an average 

 daily growth rate of 2.89 mg/day. The specific growth 

 rate, 



In(wt), - ln(wt),|/^ -to 



where In(wt) = log,, weight, 

 t, = day i. 

 U) = day 0, 



exhibited a decrease as yolk was depleted and then in- 

 creased to a peak on day-21, which was followed by a 

 decline similar to daily growth in length (Fig. 6a). 



