Hernandez and Castro: Larval growth of Engiaults nngens 



707 



Y = 64 + 47X 



Y = 5,4 exp (1 ,5 (1 -exp (-0 07*X))) 



Y = 27 5 • (1-exp (-0 03 •{ X-(-5.4)))) 



10 20 30 40 



Age in days 



Figure 4 



Models usedd to describe larval growth of the anchoveta Engraulis ringens 

 during the 1995 winter spawning season off central Chile: linear model ( — ); 



Gompertz model I ); and von Bertalanffy model ( ). Basic statistics 



for each model are shown in Table 1. 



Larval food (dinoflagellates, copepod eggs, and nauplii) 

 occurred in relatively high concentrations throughout the 

 season (Fig. 5). No differences in dinoflagellate densities 

 (Mann-Wliitney L/=4.00; P=0.296). copepod egg densities 

 (Mann-Whitney [^=7.00; P=0.861), and copepod nauplii 

 densities ( Mann-Whitney t./=5.00; P=0.456 ), were detected 

 between the periods used to classify both groups of 

 lai-val cohorts during the season. Sea surface temperature, 

 another factor that may affect lai-val growth, was higher 

 (Mann-Whitney C/=19; P=0.025) during the second period 

 of the spawning season (maximum, sea surface tempera- 

 ture: 13.5''C), probably as a result of the intrusion of off- 

 shore warmer waters to the coastal zone (Fig. 6) During 

 the first period of the season, instead, when some of the 

 upwelling events and the river plume were stronger and 



farther offshore (Castro et al.. 2000). the sea surface tem- 

 perature reached a minimum (11.1°C) in the coastal area. 



Discussion 



The deposition of the first ring in the lar\'al otoliths has 

 been associated with events in the early life history of 

 fishes, such as the onset of feeding or eye pigmentation. 

 For northern anchovy. Engraulis mordax, for instance, 

 the deposition of the first increment takes place at the 

 initiation of exogenous larval feeding or after yolksac 

 absorption which occurs five or six days after hatching 

 (Brothers et al., 1976; Methot and Kramer, 1979). Bay 

 anchovy, A/K'/joa mitchilU, completes its first otolith ring 



