臺灣東部海域中層人工聚魚器黃鰭鮪幼魚食性研究

翁進興、何珈欣、許明樹、李明安、劉光明、吳龍靜 (2016) 。臺灣東部海域中層人工聚魚器黃鰭鮪幼魚食性研究。水產研究，頁13-24。

       黃鰭鮪 (Thunnus albacares) 為臺灣東部海域中層人工聚魚器 (subsurface fish aggregating devices, SFADs) 主要漁獲魚種，但對於其生物學，特別是食性生態研究極為缺乏，因此，本研究以胃內容物分析法進行黃鰭鮪幼魚食性研究。505尾標本是延繩釣作業船所捕獲，尾叉長 (fork length, FL) 分布為36.5 ~ 97.0 cm。主要攝食餌料數量百分比 (%N) 依序為端腳類 (Amphipoda) (20.73%)、南魷 (Sthenoteuthis oualaniens) (12.30%)、鼠鱚 (Gonorynchus abbreviatus) 幼魚 (8.94%)、仿蝦蛄(Faughnia spp.) (8.57%)、頷圓鰺 (Decapterus macarellus) (5.96%) 與花鰹 (Auxis rochei) (1.12%)；攝食重量百分比 (%W) 則依序為頷圓鰺 (23.17%)、花鰹 (21.91%)、南魷 (8.29%)、仿蝦蛄 (5.17%)、鼠鱚幼魚 (3.38%) 及端腳類 (1.1%)。在餌料相對重要指數 (%IRI) 方面，魚類佔了相當重要比例，其中無法辨識的魚類佔了30.83%、頷圓鰺 14.97%，端腳類及仿蝦蛄則分別為20.12% 與10.2%。在不同尾叉長攝食餌料變化上，根據胃內容物分析顯示，當其尾叉長到達50 cm 左右時，開始進入餌料轉變期，FL < 50 cm的幼魚以端腳類與仿蝦蛄為主要餌料，FL > 50 cm 者則逐漸改變成攝食鼠鱚幼魚、花鰹及南魷。

       The yellowfin tuna (Thunnus albacares) is one of the major species caught around subsurface fish aggregation devices (SFADs) in the waters east of Taiwan. However, its biology, particularly its feeding ecology, is poorly understood. In this study, stomach content analyses were used to examine the diet and feeding habits of 505 specimens of juvenile yellowfin tuna with fork lengths (FL) ranging from 36.5 to 97 cm collected via longline around SFADs in the waters east of Taiwan. These stomach content analyses indicated that the important prey species (in terms of %N) of juvenile yellowfin tuna were Amphipoda (20.73%), Sthenoteuthis oualaniens (12.30%), larval Gonorynchus abbreviates (8.94%), Faughnia spp. (8.57%), Decapterus macarellus (5.96%), and Auxis rochei (1.12%). In terms of %W, the important prey species were Decapterus macarellus (23.17%), Auxis rochei (21.91%), Sthenoteuthis oualaniens (8.29%),Faughnia spp. (5.17%), larval Gonorynchus abbreviates (3.38%), and Amphipoda (1.10%). In terms of the percentage of index of relative abundance (%IRI), the high values were for unidentified fishes (30.83%), Decapterus macarellus (14.97%), and Amphipoda (20.12%), followed by Faughnia spp. (10.20%). The diets of juvenile yellowfin tuna with FL of <50 cm consisted primarily of Amphipoda and Faughnia spp., while the diets of tuna with FL > 50 cm were shifted toward feeding of teleost fishes such as Gonorynchus abbreviates, Auxis rochei, and Sthenoteuthis oualaniens. Based on the stomach content analyses, the yellowfin tuna changed their diets at FL of approximately 50 cm.