NDLI: Acoustic target strength of Japanese common squid, todarodes pacificus, and important parameters influencing its TS: swimming angle and material properties

Content Provider	IEEE Xplore Digital Library
Author	Donhyug Kang Iida, K. Mukai, T. Doojin Hwang
Copyright Year	2004
Description	Author affiliation: Grad. Sch. of Fisheries Sci., Hokkaido Univ. (Donhyug Kang; Iida, K.; Mukai, T.)
Abstract	The squids, one of the cephalopods, is important species in fisheries and ecology. If acoustic properties of squid can be well examined, especially target strength (TS), acoustic method can be provided a good tool for squid survey. The purpose of the study is to investigate the TS property of the Japanese common squid, Todarodes pacificus, and parameters influencing TS: swimming angle and material properties, density (g) and sound speed contrast (h). In the swimming angle measurement, the mostly head part of the squid stands below the horizontal axis, and averaged swimming angle was -17.7deg (s.d.:plusmn12.7deg). Based on the tethered TS measurements, the mean standardized TS values $(b_{20})$ were found to be highly correlated with the tilt angle, and the resultant fitted equations for b $_{20}$ were expressed as: $b_{20}=-73.3+0.48middotthetas+0.0122middotthetas^{2$ $}+0.00016middotthetas^{3}$ for 38 kHz and $b_{20}=-72.6+0.53middotthetas+0.0134middotthetas^{2$ $}+0.00014middotthetas^{3}$ for 120 kHz, where thetas is the negative tilt angle in degrees. The material properties, g ranged between 1.0209 and 1.0396 (mean 1.0288), and mean h for individual, multiple and tilted squid were 1.041, 1.042, and 1.039, respectively. In the model estimation, the estimated TS data from the measured h (1.04) were higher than those of previous studied h (1.007) and were close to maximum TS data that were obtained from live squid. The results suggest that further work is needed to conduct the TS measurement for various sized squid, and to decide suitable acoustical parameter for model estimation. These data can help in making acoustics a quantitative survey tool for biomass estimation of the squids
Starting Page	364
Ending Page	369
File Size	615520
Page Count	6
File Format	PDF
ISBN	0780386698
DOI	10.1109/OCEANS.2004.1402944
Language	English
Publisher	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Publisher Date	2004-11-09
Publisher Place	Japan
Access Restriction	Subscribed
Rights Holder	Institute of Electrical and Electronics Engineers, Inc. (IEEE)
Subject Keyword	SQUIDs Material properties Acoustic measurements Aquaculture Biomass Acoustic scattering Environmental factors Goniometers Equations Size measurement
Content Type	Text
Resource Type	Article

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