2023_programme: SEVEN YEARS OF SHIP NOISE MAPPING IN THE NORTHEAST ATLANTIC: 2015-2021

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  • Session: 20. Underwater noise in the EU Marine Strategy Framework Directive: monitoring and impacts on marine ecosystems
    Organiser(s): Jakob Tougaard, Aristides Prospathopoulos and Emmanuel Skarsoulis
  • Lecture: SEVEN YEARS OF SHIP NOISE MAPPING IN THE NORTHEAST ATLANTIC: 2015-2021
    Paper ID: 2003
    Author(s): Farcas Adrian, Putland Rosalyn, Merchant Nathan
    Presenter: Farcas Adrian
    Abstract: Large-scale ship noise mapping is needed to assess the risk of impact to marine fauna and to inform management measures (Erbe et al., 2014), but it remains a relatively new field of research. Few studies have yet produced multi-year maps, and techniques to validate maps with field measurements are still under development. To further develop this area, we produced seven years of shipping noise maps for a large portion of the Northeast Atlantic (including all UK Exclusive Economic Zone waters) and investigated the effects of applying different ship source models on validation with field measurements, as well as the potential effects of COVID-19 restrictions during 2020.\nUsing a computationally efficient modelling approach developed previously (Farcas et al., 2020), and an updated ship source model which allows the inclusion of the dependence of noise levels on ship speed and ship type in the modelling (MacGillivray and de Jong, 2021), we produced maps at frequencies ranging from 63 Hz to 4 kHz for the period 2015-2021 (inclusive) at monthly and annual resolutions. The model was validated with long-term field measurements taken at three locations in English and Welsh waters from 2018 onwards, and subsequently optimised at frequencies below 250 Hz to improve its agreement to the measurements, while remaining within physically realistic model parameters for this region. To avoid overfitting the model to the measurements, a unique optimised model was sought, such that the same model corrections would be applied throughout the model domain. At all three measurement locations, there was good overall agreement, with 57% of modelled frequency bands having mean average errors within ±6 dB, and 86% within ±12 dB.\nTo investigate interannual changes in noise levels and the possible effects of COVID-19 measures, the annual shipping noise maps for 2015-2021 were compared with the seven-year average. Noise levels in 2020 were consistently lower in the English Channel, reversing a pattern of generally increasing noise levels since 2015. This result is consistent with studies from other areas reporting changes in noise levels due to the response to COVID-19 (e.g., Sertlek, 2021). However, the increasing trend was resumed in 2021.
  • Corresponding author: Dr Adrian Farcas
    Affiliation: 1Centre for Environment, Fisheries and Aquaculture Science (CEFAS)
    Country: United Kingdom
    e-mail:

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