To determine diel and seasonal variations in abundance and species composition of fishery resources, day and night samples were collected by a bag net from April through November 1997 off Kogunsan-gundo. A total of 75 species was collected. The total catch was consisted of 71% fish, 18% shrimps, 7% cephalopods and 4% crabs. Pholis fangi and Engraulis japonicus predominated, and accounted for 87% of the total number of fish collected. Most of them were larvae and juvniles. P. fangi and Ammodyres personatus occurred from April to June, and E. japonicus occurred from July to November, suggesting that they used the coastal areas as nursery ground at the different season to avoid competition. Dominant fish larvae and juveniles showed the significant diel difference in catch.