Changes in the Ratio of Rheoreaction Types during Fish Starvation

Abstract

Changes in the motivational component of rheoreaction (the ratio of rheoreaction types) during starvation in some fish species has been analyzed. The presence of fish motivation to migrate (before starvation) is the major pattern of the future changes in the motivational component of rheoreaction resulting from starvation. All fish of the families Cyprinidae and Salmonidae studied with initially behavior as resident individuals show the same type of response to starvation. Their preference for currentwise movement increases on the 2nd–5th days of starvation, then the preference for movement against the current increases on the 7th–12th days, and the ratio of rheoreaction types approaches the initial one. Juveniles of the Black Sea salmon (Salmo trutta labrax) with a motivation to downstream migration, represent a different response to starvation: the downstream movement of individuals monotonically increased from two days after starvation.