FISHERY BULLETIN: VOL. 84, NO. 4 



100 - 



juv. Euphausia 



(6- 10mm) 



Engraulis 

 capensis 

 (15mm) 

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Engraulis 

 capensis 

 (34mm) 



Engraulis mordax 

 (85mm) 



Scomber japonicus 

 (190mm) ^~~" 



JL 



2 6 10 14 18 22 26 30 34 38 42 46 50 



60 



70 



80 



90 



STANDARD LENGTH (mm) 



Figure 6.— Percentage of larval and juvenile anchovies escaping attacks of various predators as a function of length. 

 Data for Engraulis capensis feeding on larval E. capensis are from Brownell (1984); juvenile Euphausia fed E. mordax 

 from Theilacker and Lasker (1974); Amphiprion percula fed E. mordax from Webb (1981); and others are from this study. 

 Numbers indicate length (mm) of the various predators. 



larger), the field extends from the egg (Hunter and 

 Kimbrell 1980) to about 40 mm. The field for juvenile 

 chub mackerel is much wider than that for northern 

 anchovy extending from northern anchovy eggs to 

 adults (120 mm), whereas the predation field for 

 Euphausia is restricted to the yolk-sac period 

 (Theilacker and Lasker 1974). The limited data 

 available (Table 2) provide a crude index for the up- 

 per limit of the predator field for northern anchovy 

 larvae. When the larval length exceeds about 50% 

 of the predator length little or no predation occurs. 



CONCLUSIONS 



Much of the past research on recruitment has 

 focused on early larval stages where mortality rates 

 are the highest (May 1974). Our work supports a 

 growing contention that later larval stages and early 

 juvenile stages may be as important in determining 

 year-class strength (Smith 1985) and that such ef- 

 fects might be mediated through an interaction 

 between larval growth and size-specific vulnerability 

 to predators. Our results and those of others indicate 

 that the ability of northern anchovy larvae to escape 

 pelagic predators increases throughout the larval 

 stage. On the other hand, the susceptibility of lar- 

 vae to predation may not decrease strictly accord- 

 ing to size because large larvae may be more easily 



Table 2.— Upper limit of some predator fields for larval anchovies, 

 Engraulis mordax and E. capensis. 



'Upper limit = larval size at which all larvae escape predator. 

 2 Extrapolated values. 



detected by visual feeding planktivorous fishes than 

 smaller ones. 



ACKNOWLEDGMENTS 



We wish to thank Roderick Leong for providing 

 the northern anchovy eggs on demand, Carol Kim- 

 brell for editorial assistance, and Clelia Booman and 



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