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Monthly samples totalling 1,945 yellow eels were caught by fyke net in a small bay, area 100 hectares, of a large lake in 1981 and 1982. Catch per unit effort figures showed that population density varied between months and between specific areas of the bay. Most of the eels sampled (80%) measured between 34 cm and 54 cm. Ages of a sample of 168 specimens taken in 1979 ranged from 7 to 17 years, 80 % from 8 to 13 years. Length frequencies were constant throughout the bay within months but showed changes between months. Recapture rate of 1,660 eels tagged was extremely low at 1.14%. The results showed that (1) when eel population density Is being compared between years, it is necessary to define exactly the positions where sampling takes place and (2) the eel population in this bay was not resident but appeared to be undergoing constant change throughout the warm months of the year