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