FISHERY BULLETIN: VOL. 79. NO. 1 



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Figure 3 . — Relationships between swimming speed and time during a burst for. 11 groups of northern anchovy larvae ranging in mean 

 total length from 0.23 to 1.33 cm. Panel A shows mean curves, separated into two groups for clarity. Panel B indicates the nature of the 

 data from which the curves were constructed. Curves were fitted by eye. Vertical bars show ± 2 SE. 



DISCUSSION 



Northern anchovy larvae are important 

 planktonic predators as well as being prey items 

 for other organisms. Burst swimming speeds and 

 burst swimming response ability will be impor- 

 tant in this predator-prey role because the ability 

 to rapidly strike prey and to escape strikes by 

 predators will make major contributions to survi- 

 val. 



Response ability was assayed following an elec- 

 tric shock stimulus. While this is not a normal 

 stimulus, observations on adult fish suggest re- 

 sponses to electric shock and more typical stimuli 

 are comparable (Eaton et al. 1977; Webb 1978, 

 1979). For the larval northern anchovy, response 



146 



patterns to electric shock correlated vdth expecta- 

 tions based on the onset of intermittent swimming 

 and feeding (Figure 1). Similar patterns of mat- 

 uration of the nervous system, especially the eyes 

 (O'Connell in press), and reduced vulnerability to 

 predators (Lillelund and Lasker 1971) suggest the 

 stimulus is a suitable assay for maturation of 

 locomotor coordination systems. 



Following maturation of response capabilities, 

 the effectiveness of a larva as a predator and in 

 avoiding predation will depend to a large extent on 

 locomotor performance (Lillelund and Lasker 

 1971). A model by Rowland (1974) showed speed 

 and maneuver were major factors in catch and 

 avoidance behavior that contribute to success in 

 predator- prey encounters. Larvae may be pursued 



