ECOLOGICAL AND FISHERY IMPLICATIONS OF THE DISTRIBUTION OF VENDACE RESOURCES IN LAKES MONITORED WITH AN ACOUSTIC - FISHING METHOD

摘要

Studies were carried out on the distribution and density of vendace (Coregonus albula L.) in seven lakes of Masurian Lakeland, north-east Poland. Acoustic monitoring was made using an echosounder Simrad EY-M. The data were analysed using the programme HADAS. Maps were prepared of fish distribution and density in epi- and hypolimnion, and their numbers and biomass were estimated. Water temperature and oxygen content were also registered. Control catches were made with a pelagic trawl. The obtained data were used to determine the relationships between fish migration and physico-chemical conditions. Spatial, aerial and depth distribution of pelagic fish, vendace most of all, was determined. Data on periodic species and size distributions of the fish in lakes enable their rational exploitation.