Hokkaido National Fisheries Research Institute, Fisheries Research Agency, Kushiro, Hokkaido 085-0802, Japan
To clarify the impacts of fisheries on the marine ecosystem, the relationship between the ruggedness of the seafloor and the distribution of demersal fishes was estimated on the basis of observation by a deepwater video-camera system in the fishing grounds on the continental slope off the Pacific coast of Hokkaido, Japan. Some demersal fish species (cutthroat eel, rattails, kichiji rockfish, walleye pollock, eelpouts, sculpin, and flounders) were observed. Kichiji rockfish preferred a rugged seafloor to a flat area, and the density of kichiji rockfish was higher in a topographically rugged area with high bottom water temperature. Conservation of a rugged seafloor may be necessary to maintain a favorable habitat for kichiji rockfish.