Nippon Suisan Gakkaishi 76 (4), 658-669 (2010)

Estimation of the fishing efficiency of a mid-water trawl for Pacific saury Cololabis saira using a high-frequency side-scan sonar

MIYAKO NAYA,1* YASUHIRO UENO,1 TAKASHI MOURI,1a KAZUHIRO OSHIMA,2
TOSHIHIRO WATANABE,3 KAORU FUJITA,3 KIYOSHI ITOH,4 KAZUHARU IWASAKI,4
YASUNARI MATSUO,4 YUTAKA ITOH5b AND YUICHI SHIMIZU5

1Hachinohe Station, Tohoku National Fisheries Research Institute, Fisheries Research Agency, Hachinohe, Aomori 031-0841, 2National Research Institute of Far Seas Fisheries, Fisheries Research Agency, Shimizu, Shizuoka 424-8633, 3National Research Institute of Fisheries Engineering, Fisheries Research Agency, Kamisu, Ibaraki 314-0408, 4Environmental Simulation Laboratory Co. Ltd., Kawagoe, Saitama 350-1124, 5Iwate Fisheries Technology Center, Kamaishi, Iwate 026-0001, Japan

In order to improve the accuracy of abundance estimations of Pacific saury Cololabis saira, it is important to raise the fishing efficiency precision of a mid-water trawl (type NST-99, the sampling gear used for stock assessment) for saury. Using a 500 kHz side-scan sonar (SSS), we ensonified surface waters and measured the fish number using image processing methods. Simultaneously, we tried to catch saury in the same waters with the mid-water trawl. We estimated the fishing efficiency of the mid-water trawl as 0.179 (current value used is 0.144) by comparing the number of saury caught by the trawl net per swept-area with the number of saury per swath-area estimated from analysis of SSS records.


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