708 



Fishery Bulletin 98(4) 



at the end of the second day after hatching — a time which 

 corresponds to the time of yolksac depletion ( Leak and 

 Houde, 1987). Mediterranean anchovy, EngrauUs encrasi- 

 colus, deposits its first increment during the second day 

 after hatching with completion of yolk absorption (Palom- 

 era et al.. 1988). In our rearing experiments larval ancho- 

 veta finished forming their first otolith increment at the 

 end of the third day after hatching, which coincides with 

 the end of the eye pigmentation. 



Total dmoflagellates 



n 



Copepod eggs 



□ . 



Nauplii 



U,D 



. n_ 



Date 



Figure 5 



Moan density of potential larval food items in field during the 

 winter spawning season of the anchoveta EngrauUs ringens off 

 Talcahuano. central Chile, in 199.5: dinofiagellates, copepod eggs, 

 and cnpeijnd nauplii. The vertical dashed line indicates the sepa- 

 ration ol periods considered in the groups of larval cohorts. 



Larval anchoveta finished forming their first otolith 

 increment at a larval length of 5.6 mm (estimated from the 

 rings and otolith diameter and from the otolith diameter 

 and larval length relationships). Observations of labora- 

 tory-reared anchoveta {E. ringens) larvae off Peru indi- 

 cated that the mouth and eyes become functional at 64 h 

 after hatching at a larval length of 4.03 mm (Ware et al., 

 1981). Initiation of larval feeding, however, varied from 

 3.5 to 6.8 days after hatching (mean 4.4 d), which corre- 

 sponded to estimated larval lengths between 4.10 and 

 4.16 mm. If the deposition of the first ring in lai-val 

 anchoveta coincided with the onset of feeding, then 

 our estimations of 5.6 mm at the end of the third day 

 after hatching were slightly higher than those esti- 

 mated by Ware et al., ( 1981 ). 



The three models used to fit the age and larval 

 length data of anchoveta larvae collected during the 

 winter spawning season in 1995 fitted the age and 

 larval anchovy length data appropriately for the 

 winter spawning season of 1995. A visual inspection, 

 however, revealed a slight decrease in growth rate 

 as the larvae increased in age, which suggests that 

 the nonlinear models (von Bertalanffy and Gompertz) 

 would describe larval growth better beyond the ages 

 determined in our study. 



Growth rates calculated with the three gi'owth 

 models (linear=0.47 mm/d; Gompertz=0.50 mm/d; and 

 von Bertalanffy=0.48 mm/d) were very similar to esti- 

 mations for anchoveta in other seasons (larval size 

 range 5.0-20mm=0.45 mm/d, 12.5°C, Herrera et al., 

 1985) and within ranges reported for other engrau- 

 lids. Methot and Ki-amer (1979) estimated northern 

 anchovy larval gi'owth rates between 0.34 and 0.55 

 mm/d between 13.0° and 16.2°C; for bay anchovy, 

 Anchoci mitchilU, larval growth rates between 22° and 

 30°C ranged from 0.25 to 0.58 mm/d (Fives et al., 1986; 

 Leak and Houde, 1987; Castro and Cowen, 1991); 

 and for Mediterranean anchovy, EngrauUs encrasico- 

 hts, growth rates ranged between 0.9 and 0.96 mm/d 

 for 8-mm larvae at 20°C (Palomera et al., 1988). If 

 only the larval anchovies from the upwelling areas 

 of California and central Chile are compared, then 

 the growth rates determined for the anchoveta in our 

 study (0.40-0.57 mm/d at sea temperatures between 

 11.1° and 13.5°C), are slightly higher than those esti- 

 mated for the northern anchovy at similar temper- 

 atures (0.39-0.47 mm/d at 13.0-13.2°C; Methot and 

 Kramer 1979). 



Some intraseasonal variability in growth rates of 

 the anchoveta was observed between groups of cohorts 

 during the winter spawning season, when rates from 

 linear growth models were compared. Larval growth 

 rates determined with the linear model (0.40 vs. 0. 

 57 mm/d) were within the same range reported for 

 cohorts of other clupeiforms spawning at different 

 times during the year or under different environ- 

 mental conditions within the same spawning season 

 (Methot and Kramer, 1979, Leak and Houde, 1987). 

 Larval food, as a potential factor affecting larval 

 growth rates, did not seem to be limited throughout the 



