Nippon Suisan Gakkaishi 79 (4), 638-648 (2013)

Comparison of measurements and model calculations of target strength of juvenile sandeel in Sendai Bay

RYUICHI MATSUKURA,1* KOUICHI SAWADA,2 KOKI ABE,2 KENJI MINAMI,3 HIROSHI NAGASHIMA,4
SHIROH YONEZAKI,5 HIROTO MURASE6 AND KAZUSHI MIYASHITA7

1Japan Sea National Fisheries Research Institute, Fisheries Research Agency, Chuo, Niigata 951-8121, 2National Research Institute of Fisheries Engineering, Fisheries Research Agency, Kamisu, Ibaraki 314-0408, 3Faculty of Fisheries Sciences, Hokkaido University, Hakodate, Hokkaido 041-8611, 4Miyagi Prefecture Fisheries Technology Institute, Freshwater Fisheries Experiment Station, Kurokawa-gun, Miyagi 981-3625, 5National Research Institute of Far Seas Fisheries, Fisheries Research Agency, Yokohama, Kanagawa 236-8648, 6The Institute of Cetacean Research, Chuo, Tokyo 104-0055, 7Laboratory of Marine Ecosystem Change Analysis, Field Science Center for Northern Biosphere, Hokkaido University, Hakodate, Hokkaido 041-8611, Japan

The target strength (TS) of juvenile sandeel (3.1-7.7 cm in standard length, SL) was measured for various tilt angles (−30° to 30°) at 120 kHz, and was compared with the theoretical TS calculated using the theoretical sound scattering model. The maximum TS measured at the tilt angle of 0° ranged from −68.8 to −60.8 dB, whereas the range of the theoretical TS was from −68.7 to −61.5 dB. The difference of the measured and theoretical values of the maximum TS was −1.6 to 0.9 dB, and the TS patterns showed good agreement, particularly in the range of the main lobes, in the tilt angle (−10° to 10°). The theoretical model was used to calculate the TS under the same conditions where the specimens were collected. The correlation between the SL and the maximum TS is given by the equation: TS=43.1 log SL−96.1.


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