Effectiveness of whitefish (Coregonus lavaretus L.) management in lakes with the highest yields of this fish in Poland

Abstract

Commercial catch statistics were used to analyse the landings, stocking rates and their effectiveness in a group of 12 lakes with the highest commercial yields of whitefish in the period 1967- 1994. Attention was paid to the type of stocking material as well as stocking rates, the latter varying from 3 to 12480 fish/ha in the case of larvae, from 4 to 3445 fish/ha in the case of summer fry, and from 4 to 1924 fish/ha in the case of autumn fry. Mean effectiveness of stocking, expressed in terms of autumn fry, ranged from 2.35 to 55.66 fish/kg of the catch.Most of the lakes were stocked with a variety of stocking material and no data were available on the intensity of whitefish exploitation. This hampered the analysis and reliable estimates of the effectiveness of whitefish production in lakes.lt was found that a rapid decrease of whitefish landings in the recent years was related not only to lower stocking rates, but also to low intensity of exploitation.