VISUAL AND CHEMICAL-RELEASE OF FEEDING-BEHAVIOR IN ADULT RAINBOW-TROUT

Feeding behavior of adult rainbow trout (Oncorhynchus mykiss) is relea sed by visual and/or chemical stimuli. Detection of either a condition ed Visual or a conditioned chemical stimulus creates an excitatory fee ding state within the central nervous system which turns on feeding be havior composed of swimming, turning and biting/snapping actions. Part icular amino acids that are highly effective physiological taste stimu li that are also detected through olfaction (e.g. L-proline, L-alanine , L-leucine) release the initial sequence of food searching and biting /snapping behaviors; however, an effective olfactory, but poor gustato ry, stimulus (e.g. L-arginine) is rarely effective behaviorally. After bilateral removal of the paired olfactory organs, visual stimuli alon e release the entire set of feeding behavior patterns. Since amino aci ds that are highly potent physiological taste stimuli do not release e ither feeding behavior or reflex biting/snapping actions in adult anos mic rainbow trout, it is postulated that the olfactory system detects potent taste stimuli and provides the afferent input for arousal and t he release of all feeding activity patterns.