Fish sounds are important components of Azorean soundscapes. Therefore, unraveling their patterns can contribute to a better assessment of local biodiversity dynamics.

Passive Acoustic Monitoring (PAM) is a cost-effective, non-intrusive method providing long-term information regardless of weather or logistic conditions, which can be especially useful when monitoring remote areas. Using PAM, we assess temporal dynamics of fish vocal activity in a protected seamount and validate PAM as an important tool for biodiversity assessment in deep-sea fish communities. Thus, we evaluated the annual, seasonal and diel patterns of variation of putative fish sounds identified in an Azorean protected seamount, the Condor (ca.190 m depth). Here, 3 years (2008, 2010 and 2012) of acoustic data were collected and analysed for diversity and abundance of the most prevalent fish sounds. We compared abundance and diversity of fish sounds before and after the establishment of the marine protected area in 2010, to assess its initial protection effects. We also compared abundance and biodiversity measures (richness and Shannon diversity index) of acoustic data with fishing data from deep-water longline surveys, to verify if acoustic diversity and taxonomic diversity show a similar trend. Additionally, we estimated a likely distance range of fish sound sources from the acoustic data loggers for local background noise and typical fish sound levels. Estimated detection distance of different fish sounds, considering Condor background noise level and reported fish sound source levels, were typically larger than 10 m and could reach hundreds of meters in some species suggesting that this study potentially targeted sounds of the deep-sea fish fauna. Fish acoustic activity was prevalent at dusks and nights of all years, while no overall seasonal pattern was detected. However, one sound sequence (#1) was dominant in the autumns of all studied period. A decrease in abundance and richness of sounds was observed from 2008 to 2012 in line with the results of fishing surveys. Although unexpected, these consistent trends suggest that PAM provides a reliable representation of fish biodiversity dynamics. Taken together, this study shows that monitoring fish sounds with PAM is a valid and promising tool for fish biodiversity assessment in deep Azorean seamounts.

鱼的声音是亚速尔群岛声景的重要组成部分。因此，弄清它们的模式可以有助于更好地评估当地生物多样性的动态。

被动声学监测（PAM）是一种经济高效的非侵入性方法，可提供长期信息，而不受天气或后勤条件的影响，这在监视偏远地区时尤其有用。使用PAM，我们评估了受保护海山中鱼声活动的时间动态，并验证了PAM是深海鱼群落中生物多样性评估的重要工具。因此，我们评估了在亚速尔群岛受保护的海山神鹰（cador）上发现的假定鱼声音变化的年度，季节和diel模式。190 m深度）。在这里，我们收集了3年（2008年，2010年和2012年）的声学数据，并分析了最流行的鱼类声音的多样性和丰富性。我们比较了2010年建立海洋保护区之前和之后鱼声音的丰富度和多样性，以评估其初始保护效果。我们还将声学数据的丰度和生物多样性度量（丰富度和香农多样性指数）与深水延绳钓调查的捕鱼数据进行了比较，以验证声学多样性和生物分类多样性是否显示出相似的趋势。此外，我们从声学数据记录器估算了鱼声源的可能距离范围，以获取本地背景噪声和典型鱼声水平。考虑到神鹰的背景噪声水平和报告的鱼声源水平，估计不同鱼声音的检测距离，通常大于10 m，某些物种可能达到数百米，这表明该研究潜在地针对了深海鱼类动物的声音。鱼类的声活动在所有年份的黄昏和夜晚都很普遍，而没有发现总体的季节性模式。但是，在所有研究时期的秋季，一种声音序列（＃1）占主导地位。根据捕鱼调查的结果，从2008年到2012年，声音的丰度和丰富度下降了。尽管出乎意料，但这些一致的趋势表明，PAM可提供鱼类生物多样性动态的可靠表示。两者合计，这项研究表明，利用PAM监测鱼的声音是评估亚速尔群岛深海山峰鱼类生物多样性的有效和有前途的工具。