Acoustic presence of finless porpoises around the Kansai International airport

Presence of finless porpoises around Kansai International airport was monitored by a passive acoustic monitoring system. The airport is an artificial land in the ocean and was suggested to create new habitat of marine organisms. Here we showed frequent nocturnal presence of finless porpoises at the south west of the airport where quite limited visual observation data available previously. During 4 months period from December to April in 2016, biosonar sounds of finless porpoises were detected nearly every day. Accumulated number of click trains in one hour time bin were 100 or larger in the nighttime. In contrast, approximately 50 click trains were recorded in the daytime. Ocean engineering newly created an island, Kansai International airport. This structure might create new habitat even for top predators in this water.