Changes in exploited populations of crucian carp in 706 lakes in Northeastern Poland have been observed based on the fishing records from 1951 to 1994. The lakes, covering a total area of over 120.8 thousand hectares, were divided into five size groups. The crucian carp fishery exploitation parameters, which comprised an annual catch per area unit taking into account the number of months when the lakes were exploited and the percentage of crucian carp in the total catch, were highly varied. Trend lines in the catch of this fish species were drawn for each lake size group. The rate and tendencies in the total disappearance of crucian carp from commercial fishing catches were determined. The volume and frequency of stocking with this fish species in the lakes under study were described. High irregularity of stocking was accompanied by the decreasing number of stocked lakes and the total stocked area in each lake size category.

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