2007-08-012024-05-18https://scholars.lib.ntu.edu.tw/handle/123456789/712215摘要：鮪魚為高經濟性魚類，長久以來承受過渡捕撈的壓力而面臨族群量減少的問題。鮪魚具有高度大洋洄游能力，使得許多科學性研究工作不易進行並且十分昂貴，因此現今對鮪魚洄游生活史的瞭解仍相當有限，尤其是初期生活史與生殖行為方面。本計畫的目的在於使用耳石的定齡學與穩定性碳氧同位素分析技術，解讀鮪魚的洄游生活史，耳石粉末將從耳石的核心到邊緣刮取下來，以進行鮪魚全生活史的穩定性碳氧同位素組成分析。研究對象包括長鰭鮪(Thunnus alalunga)、大目鮪(T. obesus)、黃鰭鮪(T. albacares)、太平洋黑鮪(T. thynnus orientalis)與印度洋的南方黑鮪(T. maccoyii)。從耳石的日輪與年輪微細結構可以判讀該魚的日(年)齡，而耳石的18O值可用於估算該魚所棲息的大洋環境水溫，藉由溫度資料可以提供鮪魚的棲息緯度或是深度，以及該魚在大洋中的遷徙過程，而耳石的13C值則可以反映魚類的發育、食階、生理代謝等狀態，結合年齡與穩定性同位素組成分析，本研究的結果將能提供給研究鮪魚生理生態以及漁業管理方面非常重要的資訊，並且補充以往的研究方法所無法涵蓋的全生活史解析能力。<br> Abstract: The tuna is economically highly-valued species. Due to the long-term overfishing, the populations of many tuna species have been significantly decreased. The highly migratory behaviors of tuna make the scientific researches very difficult and expensive. Therefore, the present understanding of the migratory life history of tuna is still very limited, especially for the early life history and spawning behaviors. This project aims to reconstruct the migratory life history of the tuna by otolith direct aging and analysis of otolith stable isotope composition, sequentially collected from core to edge of the otolith. The target species include albacore (Thunnus alalunga), bigeye tuna (T. obesus), yellowfin tuna (T. albacares), Pacific bluefin tuna (T. thynnus orientalis) and southern bluefin tuna (T. maccoyii). The daily and yearly age of tuna can be estimated from otolith daily growth increment and annuli, respectively. In addition, otolith 18O can be used as a proxy of ambient water temperature, which provides information of the latitude or depth where the tuna is found. The changes of ambient water temperature of developmental stage can reveal the migration of the tuna in the open ocean. Otolith 13C can reflect the progressive transitions of ontogeny, metabolism and trophic levels of the tuna. By combining the age and stable isotope composition, this study will provide critical and continuing information throughout the whole migratory life history and contribute to the presently limited understanding of the tuna.鮪魚洄游生活史耳石穩定性同位素TunaMigratory life historyOtolithStable isotope