Comparison of Habitat Environment and Trophic Level for Rare Chondrichthyans in Taiwan

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Project title

Code/計畫編號

MOST107-2611-M019-013

Translated Name/計畫中文名

台灣稀有大洋性軟骨魚類棲地環境及營養位階比較研究

Project Coordinator/計畫主持人

Shoou-Jeng Joung

Funding Organization/主管機關

National Science and Technology Council

Department/Unit

Department of Environmental Biology and Fisheries Science

Website

https://www.grb.gov.tw/search/planDetail?id=12670031

Year

2018

Start date/計畫起

01-08-2018

Expected Completion/計畫迄

01-07-2019

Bugetid/研究經費

640千元

ResearchField/研究領域

海洋科學

軟骨魚類由於豐富的種類及棲地多樣性，因而成為維持海洋生態系平衡的重要角色，然該類資源由於長期面臨漁獲壓力，如此將可能因資源量的變動而間接甚至直接影響生態系的穩定平衡，因此該類資源的保育及管理已刻不容緩。為提供日後保育管理措施擬定所需學理依據，本研究擬針對台灣周邊海域4種稀有大洋性軟骨魚類，進行棲地環境及營養位階比較之研究。鯨鯊（Rhincodon typus）及巨口鯊（Megachasma pelagios）為全球最具指標性三種濾食性鯊魚中的其中兩種。鯨鯊屬泛世界性的魚種，近20 年來台灣已經從過去的大量漁獲利用到如今加以管理甚至完全禁捕，這期間雖完成了部分漁業生物學及洄游移動行為的初步研究，但不同生活史階段及不同性別的攝食以及棲息環境的選擇仍存在諸多未解之謎。巨口鯊為稀有的大型鯊魚，至今全球僅120-130尾的漁獲紀錄，其中半數漁獲來自台灣花東外海，在2013-2017 年間更大量捕獲了約50尾，其原因為何仍不得而知。大白鯊（Carcharodon carcharias）、屬典型的掠食者，攝食策略與鯨鯊及巨口鯊截然不同，雙吻前口蝠鱝（Manta birostris）俗稱為鬼蝠魟，為中表層棲息的濾食性魟類，該二種類皆為被CITES 列入Appendix II的物種，其資源利用程度廣受國際關注。本研究擬從攝食生態學角度切入，利用4種軟骨魚類之肌肉、脊椎骨樣本進行穩定性同位素分析，並配合胃內容物分析、水文資料及漁獲資訊的調查，比較4種軟骨魚類的攝食生態與營養位階，進而探討該4種軟骨魚類在台灣周邊水域海洋生態系中所扮演的角色，期盼研究成果能提供管理策略擬定的學理依據。 Owing to their high species and habitat diversity, chondrichthyans play an important role in the marine ecosystem. In recent years, due to increase of fishing effort, chondrichthyans have been subjected to heavy fishing pressure. Therefore, to understand their potential regulatory effects in the marine ecosystem, it is essential to quantify and qualify the feeding ecology of these creatures. In order to provide more parameters for ecosystem-based management (EBM), this study conduct not only stomach content, but also stable isotope analysis. There are four species will be included in this study: whale shark (Rhincodon typus), megamouth shark (Megachasma pelagios), great white (Carcharodon carcharias), and giant manta ray (Manta birostris). The whale shark and megamouth shark are two of three filter-feeding shark species in the world. The whale shark is a circum-global shark species, and was captured numerously in the before. This species was managed and protected by now during recent two decades in Taiwan. Some preliminary studies including fishery biology and migration/movement behavior were investigated; however, there are mysteries which exist in feeding habits and habitat environments in different life history stages and sexes. The megamouth shark is a rare and large shark species. Only 120-130 individuals were recorded by now, and about 50% of them were caught in eastern Taiwan waters. There were about 50 specimens caught during 2013-2017 off Taiwan, and the main reason is still unknown. On the other hand, the great white, manta ray were listed at CITES Appendix II, and the sustainable management of these chondrichthyans species was considered. If we want to do some management decision-making in the future, the basic biological parameters were needed. In this study we will collect tissue, vertebrae for stable isotope analysis, combin the stable isotope with stomach content analysis, also investigate the information of fisheries of the 4 species. The results of this study could provide more detail parameters for the future environmental-based management.

Keyword(s)

營養位階
鯨鯊
巨口鯊
大白鯊
鬼蝠魟
台灣
trophic level
whale shark
megamouth shark
great white shark
manta ray
Taiwan

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Comparison of Habitat Environment and Trophic Level for Rare Chondrichthyans in Taiwan

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