2025_programme: Seasonal and geographical differences of underwater ambient noise around Japan

• Day: June 17, Tuesday
    Location / Time: C. THALIA at 11:00-11:20
• Last minutes changes: -
• Session: 22. Underwater noise in the EU Marine Strategy Framework Directive: implementation, monitoring, assessment and measures
  Organiser(s): Peter Sigray, Aristides Prospathopoulos, Emmanuel Skarsoulis
  Chairperson(s): Aristides Prospathopoulos, Emmanuel Skarsoulis
• Lecture: Seasonal and geographical differences of underwater ambient noise around Japan [Invited]
  Paper ID: 2267
  Author(s): Tomonari Akamatsu, Tetsuro Yabuuchi, Kensuke Kojima, Yoshiaki Aida
  Presenter: Tomonari Akamatsu
  Abstract: The coastal waters around Japan are incredibly diverse, supporting a range of tropical, warm, and cold-water species. During the winter, strong monsoons sweep across Japan from west to east, creating a stark contrast between the sea conditions on the Japan Sea side and the Pacific Ocean side. Changes in meteorological and oceanographic conditions lead to beautiful transformations in the forest landscapes and affect seafood in the coastal waters. We studied the underwater soundscapes at 10 coastal sites around Japan to collect baseline data for offshore wind farm projects and to highlight regional and seasonal differences. We deployed a standalone underwater recorder at various locations off the coast of different Japanese during summer and winter and found the clear differences between winter and summer. During most of the summer, we detected fish choruses in the evenings. In contrast, high-intensity, low-frequency broadband noise was recorded in the Japan Sea area, likely caused by the strong monsoon. This suggests that the natural background noise level is highly variable, which could mask anthropogenic sounds, such as those from offshore wind farms. For assessing the impact of noise on aquatic animals, it’s crucial to consider not only the exposure levels but also the background noise, as it affects the range and clarity of underwater communication.
• Corresponding author: Prof TOMONARI AKAMATSU
  Affiliation: Waseda University
  Country: Japan