An alternative concept to home range theory with respect to populations of cyprinids in major river systems



Homing behaviour in cyprinid species has been demonstrated by a number of research workers during the past 35 years. The British work has been principally conducted through tank experimentation with roach, gudgeon and minnows, but limited field data indicating home range behaviour have also been published. Evidence is now presented, from a fish population assessment and management programme covering 6000 km of river fisheries in the Anglian region of eastern England, to suggest that home range mechanisms do not play a significant role in the overall stock dynamics of cyprinid species in major river systems.

An alternative hypothesis which fits the range of observed circumstances more closely is described, based on a perception of cyprinid communities as totally mobile populations influenced predominantly by river flow characteristics and behavioural responses to flow and seasonal temperature factors. This concept is illustrated with a sequential series of schematic diagrams of a river catchment in which the key factor of infinitely variable movement patterns interspersed with periods of passive downstream displacement (negatively size-related) is modified by increasing degrees of interference by river structures.

The implications of the alternative concept to the management of riverine fish populations is discussed and alternative strategies to the traditional style cyprinid stockings illustrated within the paper are suggested which do not rely on home range mechanisms.