INFECTION OF EEL ANGUILLA-ANGUILLA FROM THE RIVER ELBE ESTUARY WITH 2 NEMATODES, ANGUILLICOLA-CRASSUS AND PSEUDOTERRANOVA-DECIPIENS

From October 1987 to September 1988, 1778 eels were sampled at monthly intervals in the Elbe estuary, Germany, and examined for parasites in the swimbladder and muscle. Juveniles and adults of the nematode Anguillicola crassus were the only parasites found in the swimbladder and L-III stages of the nematode Pseudoterranova decipiens were the only parasites found in the muscle. Averaged over all samples, 57.7% of the eel were infected with A. crassus and 3.7% with P. decipiens. Prevalence decreased for A. crassus with increasing fish length, but increased for P. decipiens. No clear seasonal fluctuations in parasite frequency were detected. Infection with A. crassus could not be related to any change in condition factor or liversomatic index. Some P. decipiens from the muscle of smelt after experimental oral transfer settled in the body cavity and muscle of eel. The majority of these nematodes, however, penetrated through the stomach wall, muscle and skin and left the eel.