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Please use this identifier to cite or link to this item: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/39408

Title: Ex situ and in situ measurements of juvenile yellowfin tuna Thunnus albacares target strength
Authors: Hsueh-Jung Lu;Myounghee Kang;Email author;Hsing-Han Huang;Chi-Chang Lai;Long-Jin Wu
Contributors: 國立臺灣海洋大學:環境生物與漁業科學學系
Keywords: Target strength;Fork length;Yellowfin tuna;FAD;Swim bladder
Date: 2011-09
Issue Date: 2016-12-09T08:15:33Z
Publisher: Fisheries Science
Abstract: Abstract:To provide target strength (TS) information for estimating the body length of yellowfin tuna Thunnus albacares and its abundance around fish aggregating devices, TS was measured ex situ and in situ. In the ex situ TS measurements, two cameras synchronized with a 200 kHz echosounder were used to obtain the precise orientation of the yellowfin tuna under free swimming conditions. The ex situ TS (dB re 1 m2)–fork length (FL, cm) regression was: TS = 27.06 log (FL) − 85.04. Ex situ TS was found to reach its maximum in the tilt angle range of −15° to −20° after excluding TS samples with insignificant correlation to the tilt angle. The angle between the vertebra and the swim bladder was approximately 25° according to X-ray images, supporting the above tilt range. The relationship between the swim bladder volume (VSB, ml) and the fork length was: VSB = 0.000213 FL3. The results from the in situ TS measurements indicated that the tilt angle was highly concentrated between −10° and 15°. The results from a calculation using the ex situ TS–FL equation with the fork length from biological sampling agreed strongly with the average in situ TS.
Relation: 77(6), pp.903-913
URI: http://ntour.ntou.edu.tw:8080/ir/handle/987654321/39408
Appears in Collections:[環境生物與漁業科學學系] 期刊論文

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