Investigation method for the biomass of kichiji rockfish by hovering type AUV

We surveyed the biomass of valuable kichiji rockfish using hovering type AUV Tuna-Sand which developed for observation of the seafloor, in Kitami-Yamato bank in northern ocean of Japan at June 2013. The AUV took about 5,300 photography of the seafloor for over 24 hours. The photograph had 37 kichiji rockfishes 90 mm to 340 mm long. Kichiji rockfishes which were taken several times by the AUV stayed on the seafloor at same attitude. TS_076 dive point of 652 m depth had most number of kichiji rockfish and many brittle stars. TS_077 dive point of 305 m depth had two fishes although the AUV observed the broadest range in all dive points. In TS_079 dive, the AUV observed ten fishes although observation area was the smallest, and fish density (= number per 1 ha) was over 220 /ha. Made photomosaic shows that a kichiji rockfish stayed in oneself without troop and shortest distance between two fishes was about 4.0 m.