Eel, Anguilla anguilla L., stock and yield in Polish lakes

Abstract. Details of mean annual slocking rate and catch of eels in a random sample of 68 Polish lakes over a period of 36 years are presented. Multiple correlation and curvilinear regressions are used to assess the effectiveness of stocking. Maximum stocking rate of 275 elvers/ha/year and maximum catch of 5.2 kg/ha were determined. Yields per recruit were highest in the lakes in which the greatest catches of other fish were made and stocking was most effective in lakes of depth less than 5 m.
The theoretical maximum catch of 5.2kg/ha was very much less than maxima observed elsewhere. Two possible contributory factors are the Polish practice of using relatively large-meshed seines for fishing, permitting the escape of eels of less than 50cm and the relatively small number of potential competing fish species in fisheries such as that of Lough Neagh in Ireland.