Room: 3-370
Speaker Name:
Prof. Tomonari Akamatsu
Affiliation:
Professor, Research Organization for Nano & Life Innovation, Waseda University
Abstract:
Underwater sound recordings have been collected globally in recent years using both stationary and mobile acoustic receiving systems, which are now commercially available and widely deployed in coastal and offshore waters. However, identifying sound sources remains a significant challenge, limiting the detailed analysis of ocean acoustic data. Once key sound production characteristics—such as spectral properties, phonation rates, and source level distributions—of target species are established, underwater acoustic recordings can be effectively used for environmental assessments and marine spatial planning.
Acoustic biologging has provided insights into the echolocation characteristics of dolphins and porpoises, while passive acoustic monitoring (PAM) has facilitated their detection based on their frequent production of ultrasonic signals. PAM was applied to assess the environmental impact of Japan’s first offshore wind turbine, revealing a temporary absence of porpoises around the turbine site during the construction phase, while no such impact was observed at a control site located 2 km away. Porpoise presence recovered one year after construction was completed.
Beyond porpoises, annotated recordings of fish and crustacean sounds have enabled the visualization of the daily distribution of three distinct taxa on spatial maps, revealing coexisting predator-prey distributions with implications for fisheries resource management. In another case, unsupervised classification of long-term coral reef sound recordings has revealed phenological changes in ocean soundscapes. When sound sources are systematically annotated, the seasonal and diurnal acoustic presence of whales and fish can be monitored, providing valuable data for assessing climate change impacts.
Given the dynamic nature of the underwater environment, temporal variations must be considered in marine spatial planning for effective ocean management. Passive acoustic monitoring offers a promising tool for integrating spatiotemporal dynamics into future marine conservation and resource management strategies.
Bio:
Tomonari Akamatsu is a professor at Waseda University. He was educated in theoretical physics at Tohoku University and received Ph.D. (agriculture) from Nihon University in 1996. His majors are underwater bioacoustics and passive acoustic monitoring of aquatic creatures. He was a senior researcher of National Research Institute of Fisheries Science until 2019 and temporarily studied at National Institute of Polar Research in 1997 and Thomas Hunt Morgan School of Biological Sciences, University of Kentucky as a visiting scholar during 1999-2000. He was a director at Policy Research Department of Ocean Policy Research Institute of Sasakawa Peace Foundation during 2000-2024. He is a distinguished lecturers of IEEE (OES) since 2025. He is a member of cetacean and sirenian specialist groups of IUCN, ISO/TC43/SC3. He serves for the technical committee of Animal Bioacoustics of The Acoustical Society of America, Nominations and Elections Committee of The Society for Marine Mammalogy and various academic services. He was awarded competitive research grants such as CREST, KAKENHI and BRAIN and published over 200 peer reviewed papers and book chapters.