FISHERY BULLETIN: VOL. 69, NO. 2 



Starved larvae exhibited a slow decline in 

 dry weight after yolk absorption, with little 

 variability between larvae (Table 2). Although 

 rudiments of the hypural elements were just 

 discernible in starved larvae on day 7, their 

 notochords never showed evidence of upward 

 flexion, even as late as day 16. On day 16, ossi- 

 fication in starved larvae was comparable to 

 that in fed larvae from day 4 or day 7, with 

 only the cleithrum and a few elements of the 

 cranium and visceral skeleton taking up alizarin. 



The lengths and weights of 20-day-old larvae 

 from the delayed feeding series (containers 

 #1-6) are listed in Table 3, and in Figure 2 the 



Table 3. — Length and weight of 20-day-old larvae with 

 different times of initial feeding, x = mean, SD =: 

 standard deviation, n = number of larvae measured. 



10 

 AGE (days) 



Figure 2. — Dry weights of 20-day-old larvae with dif- 

 ferent times of initial feeding. Means and ranges are 

 plotted, and the number of 20-day-old larvae measured 

 in each group is given in parentheses. Dashed lines con- 

 nect mean weights at day 20 with the mean weights of 

 unfed larvae on the days when feeding was initiated. 



weights are plotted and connected by dotted lines 

 to the weights of starved larvae on the days 



when food was first off"ered. As expected, the 

 later the initial feeding, the lower the mean 

 weight on day 20, although the range of weights 

 of larvae fed from day 4 falls within that of lar- 

 vae fed from day 1, and larvae fed from days 

 13 and 16 likewise overlap (Figure 2) . The rate 

 of gain in weight decreases with delay of initial 

 feeding, as indicated by the decreasing slopes 

 of the dotted lines in Figure 2, but these rates 

 are similar to those of larvae feeding for com- 

 parable lengths of time from day 1 (e.g., the 

 weight gain of fed larvae between days 1 and 10 

 is about the same as that of larvae fed initially 

 on day 10 and sampled on day 20) . Larvae fed 

 from days 1, 4, and 7 had completed notochordal 

 flexion by day 20, and those fed from day 10 

 were at an intermediate stage of flexion at this 

 time; in those fed from days 13 and 16, the 

 process of flexion had not yet begun by day 20. 

 Larvae from both the fed series and the delayed- 

 feeding series indicated that notochordal flexion 

 did not begin until a length of about 11 mm and 

 a dry weight of about 1 mg had been reached. 

 Condition factors have been used in the past 

 to assess the nutritional state of fish larvae 

 (Hempel and Blaxter, 1963; Blaxter, 1965) and 

 were calculated for each sample in the present 

 experiment as 



(mean dry weight, mg) 

 (mean standard length, mm) 



X I0> 



Figure 3 A shows that after day 4, the condition 

 factors for fed larvae increased until the end 

 of the experiment on day 25, while those for 

 starved larvae, after showing a slight rise on 

 day 7, decreased until the final sampling on day 

 16. As shown in Figure 4A, the condition 

 factors of 20-day-old larvae decreased in groups 

 for which initial feeding had been delayed 7 days 

 or more, with larvae fed from day 16 showing a 

 condition factor between those of starved larvae 

 10 and 13 days old. 



FEEDING INCIDENCE 



On day 4, larvae which had been oflfered food 

 since day 1 showed a higher feeding incidence 

 (88 ^fc) than those which were given food for 



418 



