Van Horn Cameron J, Candelmo Alli C, Heppell Scott A, McCoy Croy R M, Pattengill-Semmens Christy V, Waterhouse Lynn, Cherubin Laurent M, Taylor J Christopher, Michaels William, Locascio James, Ibrahim Ali K, Semmens Brice X
Scripps Institution of Oceanography, University of California, San Diego, La Jolla, California, USA.
Reef Environmental Education Foundation (REEF), Key Largo, Florida, USA.
Ecol Appl. 2025 Jul;35(5):e70081. doi: 10.1002/eap.70081.
Passive acoustic monitoring is a cost-effective, minimally invasive technology commonly used to study behavior and population dynamics of soniferous fish species. To understand the strengths and limitations of acoustic monitoring for this purpose at fish spawning aggregations (FSA) requires an assessment of the variability in aggregation-associated sounds (AAS) as a function of time, space, and proximity for spawning fishes of interest. Here, we evaluate temporal and spatial trends in the detection of AAS by Nassau Grouper (Epinephelus striatus) using an array of six hydrophones deployed across a large Nassau Grouper FSA at Little Cayman, Cayman Islands. We collected continuous data for nine days during a winter spawning season and subsequently used an automatic classifier to extract the embedded Nassau Grouper AAS. Using these data, we analyzed variability in spatiotemporal AAS detection rates across the array with a Bayesian mixed effects model. We found high variability in the detection of AAS across the spawning site, with positive correlations among neighboring hydrophone pairs trending toward negative correlations with distances exceeding 350 m. Indeed, temporal trends in AAS rates at the spawning site were approximately inverted at the two most distant hydrophones (~600 m). Across the hydrophone network, our model predicted strong positive effects of fish proximity, spawning behavior, and crepuscular periods on detected AAS. Our findings suggest hydrophone placement can strongly influence AAS detection rates and even basic temporal patterns in AAS across the spawning season. Given both the vagaries of movement and behavior of aggregating fish at spawning sites and the limits of AAS detection using standard monitoring tools, we suggest spawning site acoustic monitoring programs deploy hydrophone arrays of sufficient size to capture the site-wide trends in AAS rates if possible; this is particularly true if researchers hope to compare/contrast AAS rates between spawning sites or across seasons for the purpose of population assessment.
被动声学监测是一种经济高效、微创的技术，常用于研究发声鱼类的行为和种群动态。要了解在鱼类产卵聚集区（FSA）进行声学监测的优势和局限性，需要评估与聚集相关声音（AAS）的变异性，该变异性是感兴趣的产卵鱼类的时间、空间和接近程度的函数。在这里，我们使用部署在开曼群岛小开曼岛一个大型拿骚石斑鱼产卵聚集区的六个水听器阵列，评估了拿骚石斑鱼（Epinephelus striatus）对AAS的检测的时间和空间趋势。我们在一个冬季产卵季节连续九天收集数据，随后使用自动分类器提取嵌入的拿骚石斑鱼AAS。利用这些数据，我们用贝叶斯混合效应模型分析了整个阵列时空AAS检测率的变异性。我们发现整个产卵场对AAS的检测存在高度变异性，相邻水听器对之间的正相关在距离超过350米时趋向于负相关。实际上，在两个最远的水听器（约600米）处，产卵场AAS率的时间趋势大致相反。在整个水听器网络中，我们的模型预测鱼类接近程度、产卵行为和黄昏时段对检测到的AAS有强烈的正向影响。我们的研究结果表明，水听器的放置会强烈影响AAS检测率，甚至影响整个产卵季节AAS的基本时间模式。鉴于产卵场聚集鱼类的运动和行为变幻莫测，以及使用标准监测工具检测AAS的局限性，我们建议产卵场声学监测项目尽可能部署足够大的水听器阵列，以捕捉整个场地的AAS率趋势；如果研究人员希望为了种群评估的目的比较/对比不同产卵场或不同季节的AAS率，情况尤其如此。
