As a part of our general effects to develop a technique to eliminate outside fish invading a dam reservoir, we examined for the appearance of fish in an artificial grass bed made of carbon fibre in the Nomura Dam reservoir of the Hiji River, Ehime Prefecture between April and November, 2005. During the experimental period, the water depth of the artificial grass bed site changed with movement by the wind of the driftwood fence attached and the dam operation in 3.2 m-11.9 m (an average of 7.9 m). Since no significant correlation was found between the movement of the artificial glass bed and the number of captured individual fishes, was little found, it was considered that there possibility that the movement of this artificial grass bed affected the amount of captured fish. A total of 10 species of 3 families in 2 orders of fishes representing 46,516 individual fish was caught during the experimental period, and most of the samples exhibited larva and juvenile stages (99.8 % of which were offspring and young fish). The number of individuals was high in early summer (7,361 fish at maximum), and no individuals appeared in the autumn to winter season. The number of collected specimens consisted of 59.9 % bluegill, Lepomis macrochirus, 34.1 % of lacustrine goby, Rhinogobius sp. OR, 5.5 % chub, Zacco platypus, 0.4 % of largemouth bass, Micropterus salmoides, and 0.1 % of other types of fish. The artificial grass bed in this study was considered to be an effective nursery ground of the early development stage of some fishes in the reservoir where a natural emergent plant belt and a natural submerged plant belt hardly developed. The artificial grass bed proved effective as a means to rid the waters of bluegill, Lepomis macrochirus. However, the issue remains regarding preventing the capture other of fishes together with them.
