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a fish at distances of 20–300 cm did not affect the swimming speed or turning of the euphausiids, suggesting that they did not respond to the presence of a potential predator at these distances. Euphausiids moved primarily obliquely in the vertical plane, with few individuals moving directly up or down, even during periods of vertical migration at dusk. Lampert, 1989). Although ity to alter predation risk activity comes at a cost: d increases steeply with Childress, 1983; Buskey, predator–prey processes characterize their swim-imming behavior of zoo-ronment remains poorly can be attributed to the d the lack of instrumenta-behavior remotely. The and echosounders) com-ies integrate information ifficult to infer the behav-). Interest in zooplankto