IN SITU AND EX SITU TARGET STRENGTH MEASUREMENT OF MESOPELAGIC LANTERNFISH, DIAPHUS THETA (FAMILY MYCTOPHIDAE)

Authors

Kouichi Sawada, National Research Institute of Fisheries Engineering, Fisheries Research Agency, 7620-7 Hasaki, Kamisu, Ibaraki, 314-0408, Japan.Follow
Kazuhisa Uchikawa, Japan Sea National Research Institute, Fisheries Research Agency, 1-5939- 22 Suido-cho, Chuo-ku, Niigata, 951-8121, Japan.
Tomohiko Matsuura, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minatoku, Tokyo, 108-8477, Japan.
Hiroya Sugisaki, National Research Institute of Fisheries Science, Fisheries Research Agency, 2-12-4 Fukuura, Kanazawa-ku, Yokohama, 236-8648, Japan.
Kazuo Amakasu, Tokyo University of Marine Science and Technology, 4-5-7 Konan, Minatoku, Tokyo, 108-8477, Japan.
Koki Abe, National Research Institute of Fisheries Engineering, Fisheries Research Agency, 7620-7 Hasaki, Kamisu, Ibaraki, 314-0408, Japan.

Abstract

Acoustic target strengths (TS) of myctophid fish Diaphus theta were measured in situ at 70 kHz off the east coast of Hokkaido by tethering an acoustic-optical system (the Japanese Quantitative Echosounder and Stereo-video Camera System or J-QUESTχ) at a depth of 150 m from a research vessel. Fish length distributions were obtained from daytime hauls taken with a frame trawl after the TS measurement. Measured average TS () and a standard length (SL) in cm gave the empirical length - average TS relationship, = 20logSL70.6, assuming that the linear TS is proportional to the square of the SL. A laboratory TS measurement and theoretical modeling of D. theta support the estimated length - average TS relationship.

Recommended Citation

Sawada, Kouichi; Uchikawa, Kazuhisa; Matsuura, Tomohiko; Sugisaki, Hiroya; Amakasu, Kazuo; and Abe, Koki (2011) "IN SITU AND EX SITU TARGET STRENGTH MEASUREMENT OF MESOPELAGIC LANTERNFISH, DIAPHUS THETA (FAMILY MYCTOPHIDAE)," Journal of Marine Science and Technology: Vol. 19: Iss. 3, Article 10.
DOI: 10.51400/2709-6998.2196
Available at: https://jmstt.ntou.edu.tw/journal/vol19/iss3/10