FISHERY BULLETIN: VOL. 85, NO. 2 



Table 7. — Width frequency of prey eaten by northern anchovy (n) related to their diets and 



to their age and size. 



'Apparent density of prey <150 ^jm = 2/mL. 

 ^Apparent density of prey <150 nm = 0.1/mL. 

 ^Apparent density of prey <150 ^im = 1/mL. 



fers <150 ^m was equivalent to about 2 and 0.1/mL. 

 In sum, the larvae switched to eating prey >150 yim 

 on day 6 in the high-density rotifer treatment, day 

 7 in the low-density treatment, and day 8 in the 

 copepod treatment (Table 7). If the analysis is based 

 on larval size instead of larval age, selection for prey 

 >150 /um occurs at 4.6-5.0 mm for northern anchovy 

 fed the rotifer diets and at 5.6-6.0 mm for those fed 

 the copepod diet (Table 7; Fig. 1). 



Feeding intensity was highly variable on all diets. 

 The observed stomach contents can differ by as 

 much as a factor of three (Fig. 2) from the pre- 

 dicted stomach contents (C^ax) used in the feeding 

 models. 



At high rotifer densities, northern anchovy filled 

 their guts at a faster rate and consumed more. On 

 average, fish eating the high-density rotifer diet 

 were full within 2 hours, while those eating a low- 

 density diet were full in about 3 hours. Comparing 

 the average observed stomach contents, and ex- 

 cluding empty stomachs, for fish of equal age shows 

 that all larvae eating at the high prey density ate 

 more than their counterparts eating at lower prey 

 densities (Table 8). 



Growth 



Hunter (1976) showed that the length-weight rela- 



100 



u 



o. 



a. 



S 

 ID 

 (/) 



Z 



o 

 o 



>• 

 m 

 a. 

 a 



4.0 5.0 6.0 7.0 8.0 9.0 



ANCHOVY STANDARD LENGTH (mm) 



10.0 



Figure L— Size of copepod prey eaten by northern anchovy related to fish size. 

 See Table 1 for copepod width classes. 



218 



