臺灣西部中華白海豚聲紋特徵與簽名哨聲鑑定研究

Abstract

本研究針對臺灣西部沿海的中華白海豚（Sousa chinensis）進行調查，選定臺中港外海及雲林新虎尾溪口兩大目擊熱區，整合船隻目視調查、拖曳式聲學陣列及底碇式聲學監測技術 。研究旨在分析海豚的喀嗒聲（clicks-train）與哨叫聲（whistles），並嘗試利用「孤立個體判別法」與「SIGID（Signature Identification）」方法，辨識潛在的簽名哨聲並探討聲紋與行為之關聯，期能為白海豚保育對策提供科學依據 。 研究結果顯示，在2024年臺中港的調查中，於6月10日記錄到編號 OAC040 個體在孤立游走狀態下，連續發出具高度一致性的Downsweep型態哨叫聲，判定為 OAC040 的潛在簽名哨聲 。應用 SIGID 標準在雲林新虎尾溪口鑑定出兩組潛在簽名哨聲：分別是2021年5月7日時含母子對群體記錄到的平直型（Flat）哨叫和2024 年 8 月 13 日在含母子對群體中發現的正弦型（Sine）哨叫 。 本研究成功偵測到特定個體的潛在簽名哨聲，為台灣首次對中華白海豚個體的簽名哨聲建立，證實了聲學個體辨識的可行性。鑑於目前國內相關調查多由不同單位獨立執行，建議後續應加強跨單位資源整合，持續累積聲紋資料以建立專屬資料庫，並針對中華白海豚哨叫聲特性修正 SIGID 判別條件。簽名哨聲有助於突破目視調查之限制，即使在無法辨識視覺特徵或夜間監測的情況下，仍能有效追蹤個體身分與棲地利用模式。

This study investigated the Indo-Pacific humpback dolphin (Sousa chinensis) along the western coast of Taiwan, focusing on two major sighting hotspots: the offshore waters of Taichung Harbor and the Xinhuwei River estuary in Yunlin. An integrated approach combining vessel-based visual surveys, towed acoustic arrays, and bottom-mounted acoustic monitoring was employed. The objective of this study was to analyze dolphin click trains and whistles, and to apply the isolation-based identification method and the Signature Identification (SIGID) method to identify potential signature whistles and to explore the relationship between acoustic signatures and behavior, thereby providing a scientific basis for conservation strategies for humpback dolphins. The results showed that during surveys conducted at Taichung Harbor in 2024, an individual identified as OAC040 was recorded on June 10 while traveling alone and repeatedly producing highly stereotyped downsweep-type whistles. These whistles were identified as the potential signature whistle of individual OAC040. Using the SIGID criteria, two sets of potential signature whistles were identified at the Xinhuwei River estuary in Yunlin: a flat-type whistle recorded on May 7, 2021 within a group containing a mother–calf pair, and a sine-type whistle recorded on August 13, 2024 within a group containing a mother–calf pair. This study successfully detected potential signature whistles from specific individuals, representing the first establishment of individual-level signature whistles for Indo-Pacific humpback dolphins in Taiwan, and demonstrating the feasibility of acoustic-based individual identification. Given that related studies in Taiwan are currently conducted independently by different organizations, future efforts should strengthen inter-agency collaboration and data integration, continue accumulating acoustic signature data to establish a dedicated database, and refine SIGID classification criteria to better accommodate the whistle characteristics of Indo-Pacific humpback dolphins. Signature whistles have the potential to overcome the limitations of visual surveys, enabling effective tracking of individual identity and habitat use patterns even when visual identification is not possible or during nighttime monitoring.