IMAI, TOSHITAME (Kanagawa Pref. Fish. Exp. Stn.), MICHIMASA CHIKAYAMA (Dept. Fish. Kanagawa Pref.), SAICHI KANASUGI (Kanagawa Pref. Fish. Exp. Stn.), KAZUNARI OGAWA, RYUICHI MITOMI and AKIHIKO MAKI (Chiyoda Dames & Moore Co. Ltd.). 1988. The structure of rock components of artificial reef and the spatial disbribution of abalones. Benthos Research (Bull. Jap. Assoc. Benthology), 33/34; 43-51. An underwater investigation was made by SCUBA diving at Matsuwa, Miura Peninsula, Kanagawa Prefecture, in order to clarify the favorable habitat structure for abalones on the artificial reef. The reef was constructed by a pile of rocks encircled by a concrete frame, considerable number of three abalone species, Haliotis sieboldii, H. gigantea and H, discus had been introduced previously. Firstly, all abalones attached on rocks of the reef were fished, and topographic features of the whole reef were surveyed. Then, all rocks were heaved up on board the boat for measuring their shape and size. All abalones caught with the location data, and identified to the species. The data were analyzed using computer graphics, on the raletionships between the structure of rock components and the spatial distribution of each abalone species. The reuslts were summarized as follows: (1) most of abalones were found close to the bottom less than 25cm in height, (2) most of abalones attached on shaded faces of piled rocks, (3) concerning the habitat preference by species, Haliotis discus outnumbered on the effectively sheltered faces of rocks not accessible by divers. This habit makes the species most difficult to retrieve in fishing among three abalone species. (4) Light condition was very important for abalone distribution. As for favorable condition of resting site, effectively sheltered and appropriately shaded condition seems to be more important than the shape and capacity of the room created by rock components.
