ANGUILLICOLA-CRASSUS LARVAE IN CORMORANTS PREY FISH IN VISTULA LAGOON, POLAND

The presence of A. crassus larvae in herring, stickleback, perch, ruff e, pike-perch, bream and roach regurgitated by cormorants from a large breeding colony at Katy Rybackie in Vistula Lagoon, Poland, was inves tigated. Larvae of nematode were detected only in ruffe, the dominant species in the diet of the cormorant (58% of the weight of fish consum ed). Mean intensity of infection was 1.57 larva per infected host (max . 5.0) and mean abundance was 0.52 larva per examined ruffe. On the ba sis of the infection rate (33.3%), it was estimated that cormorants el iminated 150 tons of infected ruffe yearly.