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研究報告

更新日期: 2015-02-09
點閱數: 1,319

南方黑鮪及太平洋黑鮪之年齡成長與其生態研究

年度 2013
計劃名稱 南方黑鮪及太平洋黑鮪之年齡成長與其生態研究
中文摘要 本研究計畫訓練科學觀察員於台灣延繩釣漁船上採集南方黑鮪(Thunnus maccoyii)的耳石,並且判讀南方黑鮪耳石年齡與太平洋黑鮪(Thunnus orientalis)耳石年輪。觀察員在2012年於中印度洋採集33顆南方黑鮪魚頭,經由年齡查定後,其年齡範圍為1-4歲,平均年齡1.9 ± 0.7歲,另外有一批於2007年採集於中印度洋的南方黑鮪耳石,經年齡查定,其年齡範圍為2-5歲,平均年齡3.4 ± 0.9歲。2012年觀察員於國內港口採集到168尾太平洋黑鮪耳石,其平均年齡為15.5 ± 3.9歲(6-26歲)。比較歷年(2002-2013年)觀察員所量測的太平洋黑鮪尾叉長,發現魚體的平均長度由210 cm逐年遞增到230 cm,所估算的平均年齡也由11歲逐漸遞增到17歲,造成此現象的可能的原因於內文有詳細討論,由未成熟的幼魚入添減少可能是最主要原因。
英文摘要 In this project, we trained scientific observers to collect otoliths of southern bluefin tuna (SBT, Thunnus maccoyii) on Taiwanese longline vessels in the Indian Ocean. The otoliths collected from SBT and Pacific bluefin tuna (PBT, Thunnus orientalis) were used for age estimation. In 2012, 33 SBT heads were collected in the central Indian Ocean and otoliths were removed in the lab. The estimated mean ages were 1.9 ± 0.7 years (range: 1-4 year). Another batch of SBT otolith were collected in the central Indian Ocean 2007 and these samples were aged this year. The mean age of year 2007 samples was 3.4 ± 0.9 years with a range from 2-5 years. The observers also collected otoliths from 168 PBT landed in domestic harbors. The estimated mean age for these PBT was 15.5 ± 3.9 years (rang: 6-26 years). The historical length data of the landed PBT measured by the observers showed gradually increasing from approximately 210 cm at year 2002 to 230 cm in recent years (2010-2013). The estimated mean age of the landed PBT also gradually increase from approximately 11 to 17 years. The decreasing recruitment of the immature PBT might be the main reason that cause the increasing trend of mean size and age of PBT landed in Taiwan although other possibilities were carefully discussed in this report.
計畫編號 102農科-11.1.1-漁-F3(3)
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