Acoustic evaluating the Baltic fish behaviour

Acoustic methods could play an important role in studies of fish group behaviour in relation to environmental factors, being one of the most promising tools of research of ecosystems. The paper presents new conceptions of treatment acoustic, biological and hydrological data collected during surveys of pelagic fish resources. A method of macrosounding was enriched by complex imaging of environmental factors for single transects. More developed version, called "matrix macrosounding", deslinied for description of selected cross-sections, characteristic for the Baltic ecosystem, was introduced and examples of its application for short-term or long-term ecological studies were given. Basic diel fish environmental preferences were estimated owing to correlating acoustic and hydrological data collected over the period 1981-1996 in the southern Baltic. In a consequence, preliminary models of day life-eycle of fish in relation to main environmental factors were formulated and applied for fish behavioural studies. Examples of fish behaviour models, determined for the autumn are shown.