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A Review of Passive Acoustics Monitoring Results in the CoastalWaters off Western Taiwan for the Past Decade38Marine Research of the National Academy of Marine ResearchDOI: 10.29677/MR.202406_4(1).0004 Taiwan is situated at the convergence of two tectonic plates. In its northeastern waters, the Philippine Sea plate subducts northward under the Ryukyu arc, while in the south, the Eurasian plate subducts under the Luzon arc (Sibuet & Hsu, 2004), creating intricate seafloor topography. The eastern seabed drops to depths of 1,000 meters within 10 kilometers offshore, and is characterized by troughs, forearc basins, ridges, and ocean basins. The western continental shelf, including the Taiwan Strait, generally has depths of under 70 meters, with plains, sandbars, shoals, and sand dunes prevailing. To the south, depths range up to 1,200 meters, encompassing canyons, ridges, and submarine volcanoes. This complex topography significantly influences ocean currents, with three major water masses impacting Taiwan's waters: the mainland coastal current, the Kuroshio tributary, and the South China Sea Warm Current, particularly in the western region. The area experiences diverse seasonal currents, characterized by high coastal humidity and temperatures driven by monsoon winds (Belkin & Lee, 2014). Taiwan's marine biodiversity thrives due to its varied marine topography and hydrological conditions. Early visual and photographic surveys were constrained by weather, walrus presence, water depth, and distance, impeding repeated assessments of organisms in specific habitats over time, hindering accurate marine biodiversity descriptions (Mooney et al., 2020). Nowadays, cost-effective passive acoustic instruments enable wide-band and long-term ocean observations, offering insights into spatiotemporal changes, including earthquakes, climate, biology, and anthropogenic activities in specific sea areas, as well as environmental changes like pile driving or dredging (Browning et al., 2017; Duarte et al., 2021; Gibb et al., 2019). To monitor earthquake and tsunami activities in Taiwan's eastern waters, the Central Weather Bureau launched the \Cable Hosted Observatory (MACHO)\ al., 2007). Equipped with a passive acoustic recorder and sound velocity profiler, the system allows for long-term observation of local marine mammals (Fang et al., 2012; Lin et al., 2021; Lin et al., 2015b), earthquakes (Fang, et al., 2014), and data on the physical environment, such as temperature and salinity changes, of the Kuroshio tributary (Chen et al., 2012). In the western waters of Taiwan, spurred by the government's \Saving Energy and Reducing CO2 Emissions Action Plan\sand Onshore and Offshore WP Turbines\wind turbines. Subsequently, in July 2012, the Ministry of Economic Affairs (MOEA) introduced the Offshore Wind Power Demonstration Incentive Program, with the goal of increasing the share of renewable energy in electricity generation to 20fi and offshore wind power generation to 5GW by 2025. Following the initiation of the Offshore Wind Power Demonstration Incentive Program, developers have commenced the construction of offshore wind turbines off Miaoli and Changhua in western Taiwan (Gao et al., 2021); (Liu & Ho, 2016). These endeavors necessitate comprehensive environmental impact assessments, including passive acoustic monitoring(Mooney et al., 2020) throughout the construction and operational phases of the wind turbines. Passive acoustic monitoring is employed to monitor the frequency of noise generated by working vessels (Guan et al., 2015) (Hu et al., 2022), high-intensity pile driving noise, and underwater vibrations during operation (Dahl et al., 2014; Popper, 2003; Popper & Hastings, 2009; Siddagangaiah et al., 2021). In this study, we conducted a review of passive acoustic monitoring data from 2013 to 2022 in wind farms near Miaoli and Changhua. Our analysis focused on elucidating the temporal and spatial variability of fish and cetaceans, as well as changes in the impacts on the underwater soundscape and ecosystems.1 INTRODUCTION