Abstract:

Background & Aim: As key indicator species of marine ecosystems, effective monitoring of cetacean population dynamics is of great significance to biodiversity conservation. Traditional ship-based visual survey methods are constrained by multiple factors such as sea conditions, weather visibility and labor costs, making it difficult to achieve spatial and temporal continuity of ecological monitoring. Passive acoustic monitoring (PAM) breaks through the traditional monitoring bottleneck by deploying hydrophones to receive cetacean acoustic signals and environmental noise in real-time, achieving all-weather, non-invasive and three-dimensional monitoring of cetaceans. We conducted a systematic review of cetacean acoustic monitoring literature published between 2004 and June 2024, categorizing findings into five thematic areas. Our analysis identifies recent research achievements and persistent challenges, and proposes strategic recommendations for advancing acoustic monitoring applications in China. 

Review Results: Our meta-analysis identified 1,089 relevant papers, revealing limited publication output between 2004 and 2013 followed by exponential growth post-2016. The analyzed literature coalesces into five research domains: (1) equipment development and technical methods (19.9%), (2) acoustic signals and communication patterns (18.7%), (3) population and spatial ecology (38.0%), (4) ecological behavioral patterns of cetaceans (15.1%), and (5) conservation and management applications (8.3%). Technological convergence such as deep learning has revolutionized high-throughput acoustic data processing. Contemporary research extends beyond acoustic signal types to population dynamics, soundscape ecology and behavioral patterns, establishing acoustic monitoring as a critical tool in cetacean conservation and management. 

Perspectives: This review synthesizes contemporary advancements in cetacean bioacoustics and outlines strategic pathways for China's nascent research initiatives. We propose five evidence-driven priorities to advance both scientific understanding and conservation applications: (1) advance technological innovation by developing next-generation autonomous recording systems and intelligent analytical tools tailored to cetacean vocalizations; (2) implement holistic monitoring systems that synergize multi-dimensional acoustic data with environmental and behavioral datasets through sensor network integration; (3) establish unified national archives featuring standardized protocols for data sharing and collaboration, incorporating blockchain technology for traceability; (4) strengthen interdisciplinary capacity through specialized training programs integrating marine acoustics, ecology, and computational modeling; (5) expand participatory science frameworks via targeted science communication campaigns and citizen science platforms for coastal communities. These strategic priorities aim to bridge existing research gaps and advance evidence-based cetacean conservation.

Key words: cetaceans, acoustic monitoring, deep learning, population dynamics, habitat use, conservation management