The influence of tilt angle on the acoustic target strength of the Japanese common squid (Todarodes pacificus) SCIE SCOPUS

Cited 25 time in WEB OF SCIENCE Cited 28 time in Scopus
Title
The influence of tilt angle on the acoustic target strength of the Japanese common squid (Todarodes pacificus)
Author(s)
Kang, DY; Mukai, T; Iida, K; Hwang, DJ; Myoung, JG
KIOST Author(s)
Kang, Don Hyug(강돈혁)
Publication Year
2005-06
Abstract
To measure the influence of changes in tilt angle on the acoustic target strength (TS) of the Japanese common squid (Todarodes pacificus), we conducted a series of experiments to estimate TS in relation to tilt angle and swimming angle. Swimming angle was measured in a seawater tank using two infrared, underwater cameras under dark conditions. Ex situ measurements of TS in relation to tilt angle on live specimens using a fishhook and cage method were then conducted at 38 and 120 kHz; mantle length (ML) ranged from 21 to 27 cm (mean 24.75 cm). For the more precise TS measurement with tilt angle, another set of ex situ TS measurements relative to tilt angle was made at 38 and 120 kHz on tethered, anesthetized specimens in seawater. The mean swimming angle was - 17.7 degrees (+/- 12.7 degrees s.d.). The mean TS varied from -48.6 to -44.6 dB and was relatively higher at 120 kHz than at 38 kHz, in the order of 0.7 and 2.5 dB. The empirical relationship between TS (dB) and ML (cm) is given by TS = 20 log(10)(ML) - 75.4 (r = 0.81) at 38 kHz or TS = 20 log(10)(ML) - 73.5 (r = 0.64) at 120 kHz. Based on the tethered method for the anesthetized squid, the mean standardized TS values (b(20)) were found to be highly correlated with the tilt angle, and the resultant fitted equations for b20 were expressed as: b20 = -73.3 + 0.48 X theta + 0.0122 X theta(2) + 0.00016 X theta(3) for 38 kHz and b(20) = -72.6 + 0.53 X theta + 0.0134 X theta(2) + 0.00014 X theta(3) for 120 kHz, where theta is the negative tilt angle in degrees. The mean TS based on the measurements using live squid was higher than that of tethered measurements, i.e., 2.6 dB at 38 kHz and 4.0 dB at 120 kHz. The higher mean TS in the ex situ measurements for the live squid can be explained by the influence of the low tilt angle on the overall TS data. The results can be used to understand the influence of tilt angle on the TS of Todarodes pacificus and thus improve the accuracy of biomass estimates. (c) 2005 International Council for the Exploration of the Sea. Published by Elsevier Ltd. All rights reserved.
ISSN
1054-3139
URI
https://sciwatch.kiost.ac.kr/handle/2020.kiost/5069
DOI
10.1016/j.icesjms.2005.02.002
Bibliographic Citation
ICES JOURNAL OF MARINE SCIENCE, v.62, no.4, pp.779 - 789, 2005
Publisher
ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD
Subject
COD GADUS-MORHUA; SOUND-SCATTERING; FISH; TRACKING; MODELS
Keywords
Japanese common squid (Todarodes pacificus); swimming angle; target strength; tilt angle
Type
Article
Language
English
Document Type
Article
Publisher
ACADEMIC PRESS LTD ELSEVIER SCIENCE LTD
Related Researcher
Research Interests

Marine security,Underwater Acoustics,해양방위,수중음향

Files in This Item:
There are no files associated with this item.

qrcode

Items in ScienceWatch@KIOST are protected by copyright, with all rights reserved, unless otherwise indicated.

Browse