We investigated yearly fluctuation of the fish species composition of beam trawls off Maemuldo in the east southern sea of Korea, from March 2007 to November 2009. A total of 75 fish species were collected during the period. The number of fish species accumulated amounted to 54, 64 and 75 species in 2007, 2008 and 2009, respectively. The number of newly occurring species increased with time. The number of expected resident species in Maemuldo was estimated as 9 species including Conger myrister, Okamejei kenojei and Pholis nebulosa, each of which appeared more than 14 out of a total 27 times. Cluster analysis showed that the years 2007 and 2008 were closely clustered, while the year 2009 was distantly clustered with 2007 and 2008. This may be due to the high catch ratio of Clidoderma asperrimum in 2009 alone, when a low water temperature phenomenon was observed unlike the situation in 2007 and 2008.