Sensitivity of brown trout ( Salmo trutta L.) and Atlantic salmon ( Salmo salar L.) fry to amino acids at the start of exogenous feeding

Abstract

Unfed Atlantic salmon and brown trout fry of “start feed” age, were tested individually in an olfactometer with 5 μM concentrations of 15 different 1-amono acids. Certain amino acids elicited particularly high frequencies of behaviour patterns which could be associated with feeding behaviour in salmonid fry. Increased snapping (prey capture) was shown by the fry of both species in response to 1-proline and increased swimming and movement (food search) were shown in response to 1-alanine. Darting (prey pursuit) was rarely seen, but the Atlantic salmon fry showed comparatively high dart scores in response to 1-methionine. 1-Alanine, 1-proline, glycine, 1-methionine, 1-valine, 1-leucine, 1-glutamic acid and 1-lysine proved more potent than a control condition for the Atlantic salmon fry, but only 1-proline, 1-alanine, glycine, 1-arginine and 1-histidine proved to be potent stimuli for the brown trout fry. 1-Proline and 1-alanine were the most potent amino acids for both species. All other amino acids induced levels of activity similar to controls.