Analysis of whitefish (Coregonus lavaretus L.) landings and stockings in 106 lakes in 1967-1994

Abstract

Based on the fishery records, analyses were performed of the relationships between whitefish landings, stocking rates and effectiveness of stocking in 106 Polish lakes. The lakes were divided into 6 classes based on their individual area. Mean values were calculated for each lake of the level of whitefish landings and of stocking rates (quantity and kind of stocking material) from 1 ha of lake area. Effectiveness of stocking was expressed as level of stocking needed to produce 1 kg of commercial whitefish catch. Using standard prices, the three basic forms of the stocking material used were recalculated into standard autumn fry; reliability of this approach has been discussed. The results suggest that there were several reasons for the observed breakdown of whitefish production in Polish lakes. These embrace quantity and type of the stocking material used and broadly understood effectiveness of the fishery management.