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

2005 ◽  
Vol 62 (4) ◽  
pp. 779-789 ◽  
Author(s):  
Donhyug Kang ◽  
Tohru Mukai ◽  
Kohji Iida ◽  
Doojin Hwang ◽  
Jung-Goo Myoung
Keyword(s):  
Tilt Angle ◽  
Empirical Relationship ◽  
Ex Situ ◽  
Target Strength ◽  
Todarodes Pacificus ◽  
Common Squid ◽  
Acoustic Target ◽  
The Mean ◽  
Highly Correlated ◽  
Japanese Common Squid

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° (±12.7° 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 log10(ML) − 75.4 (r = 0.81) at 38 kHz or TS = 20 log10(ML) − 73.5 (r = 0.64) at 120 kHz. Based on the tethered method for the anesthetized squid, the mean standardized TS values (b20) 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 × Θ + 0.0122 × Θ2 + 0.00016 × Θ3 for 38 kHz and b20 = −72.6 + 0.53 × Θ + 0.0134 × Θ2 + 0.00014 × Θ3 for 120 kHz, where Θ 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.

scholarly journals Acoustic Target Strength of the Endangered Chinese Sturgeon (Acipenser sinensis) by Ex Situ Measurements and Theoretical Calculations

2018 ◽  
Vol 8 (12) ◽  
pp. 2554 ◽  
Author(s):  
Hui Zhang ◽  
Junyi Li ◽  
Chongrui Wang ◽  
Chengyou Wang ◽  
Jinming Wu ◽  
...  
Keyword(s):  
Theoretical Calculations ◽  
Breeding Population ◽  
Ex Situ ◽  
Target Strength ◽  
Effective Management ◽  
Chinese Sturgeon ◽  
Acipenser Sinensis ◽  
Acoustic Target ◽  
The Mean ◽  
Db Difference

The Chinese sturgeon, Acipenser sinensis, is a large anadromous and highly endangered protected species. The assessment of its breeding population in the Yangtze River is critically important for effective management and population preservation. Currently, hydroacoustic methods have been widely used to study the adult sturgeons in the river, whereas the acoustic target strength (TS) characteristics of the species have not been studied. In this study, the TS of Chinese sturgeon was carefully evaluated both by ex situ measurements and theoretical calculations. Six Chinese sturgeons (Body Length (BL): 74.0−92.6 cm) were measured by a 199 kHz split echosounder in a 10-m deep net cage. The computed tomography of a Chinese sturgeon (BL: 110.0 cm) was conducted and the Kirchhoff ray mode (KRM) method was used to estimate the theoretical TS. As a result, the mean ex situ TS range of the six specimens was from −26.9 to −31.4 dB, which was very close to the KRM estimation (~1 dB difference). Then, the KRM method was used to predict the TS of Chinese sturgeon as a function of BL in six frequencies commonly used in freshwater environments and to estimate the TS of a representative adult Chinese sturgeon (250 cm) as a function of frequency and tilt angle. This study can provide a good basis for future hydroacoustic studies on the critically endangered Chinese sturgeon.

Ex situ acoustic target strength by tilt angle and pulsation of moon jellyfish (Aurelia aurita) using frequency 70 kHz

2015 ◽  
Vol 51 (3) ◽  
pp. 295-301
Author(s):  
Eun–A YOON ◽  
Doo–Jin HWANG ◽  
HIROSE Miyuki ◽  
Kouichi SAWADA ◽  
Yoshiaki FUKUDA ◽  
...  
Keyword(s):  
Tilt Angle ◽  
Aurelia Aurita ◽  
Ex Situ ◽  
Target Strength ◽  
Moon Jellyfish ◽  
Acoustic Target

scholarly journals Acoustic Target Strength of Live Japanese Common Squid(Todarodes pacifica) for Applying Biomass Estimation

2004 ◽  
Vol 37 (4) ◽  
pp. 345-353 ◽  
Author(s):  
Donhyug KANG ◽  
Doojin HWANG ◽  
Tohru MUKAI ◽  
KohjI IIDA ◽  
Kyounghoon LEE
Keyword(s):  
Target Strength ◽  
Biomass Estimation ◽  
Common Squid ◽  
Acoustic Target ◽  
Japanese Common Squid

ACID- AND HEAT-STABLE TRYPSIN INHIBITORY PEPTIDE FROM THE VISCERA OF JAPANESE COMMON SQUID (TODARODES PACIFICUS)

2010 ◽  
Author(s):  
HIDEKI KISHIMURA ◽  
YUJIRO NAGAI ◽  
KANA FUKUMORITA ◽  
KOHSUKE ADACHI ◽  
SATORU CHIBA ◽  
...  
Keyword(s):  
Inhibitory Peptide ◽  
Heat Stable ◽  
Todarodes Pacificus ◽  
Common Squid ◽  
Japanese Common Squid

scholarly journals Spatio-Temporal Variability of the Habitat Suitability Index for the Todarodes Pacificus (Japanese Common Squid) around South Korea

2019 ◽  
Vol 11 (23) ◽  
pp. 2720 ◽  
Author(s):  
Lee ◽  
Son ◽  
Lee ◽  
Kang ◽  
Lee
Keyword(s):  
South Korea ◽  
Habitat Suitability ◽  
Sea Surface ◽  
Fishing Ground ◽  
Habitat Suitability Index ◽  
Fishery Resources ◽  
Todarodes Pacificus ◽  
Suitability Index ◽  
Common Squid ◽  
Japanese Common Squid

The climate-induced changes in marine fishery resources in South Korea have been a big concern over the last decades. The climate regime shift has led to not only a change in the dominant fishery resources, but also a decline in fishery landings in several species. The habitat suitability index (HSI) has been widely used to detect and forecast fishing ground formation. In this study, the catch data of the Todarodes pacificus (Japanese Common Squid) and satellite-derived environmental parameters were used to estimate the HSI for the T. pacificus around South Korea. More than 80% of the total catch was found in regions with a sea surface temperature (SST) of 14.91–27.26 ℃, sea surface height anomaly (SSHA) of 0.05–0.20 m, chlorophyll-a of 0.32–1.35 mg m-3, and primary production of 480.41–850.18 mg C m-2 d-1. Based on these results, the HSI model for T. pacificus was derived. A strong positive relationship (R2 = 0.9260) was found between the HSI and the fishery landings. The climatological monthly mean HSI from 2002 to 2016 showed several hotspots, coinciding with the spawning and feeding grounds of T. pacificus. This outcome implies that our estimated HSI can yield a reliable prediction of the fishing ground for T. pacificus around South Korea. Furthermore, the approach with the simple HSI model used in this study can be applied elsewhere, and will help us to understand the spatial and temporal distribution of fishery resources.

scholarly journals Continuous monitoring of catch fluctuation of Japanese common squid Todarodes pacificus using load data of squid jigging machine

2012 ◽  
Vol 78 (1) ◽  
pp. 1-7 ◽  
Author(s):  
TAKAFUMI SHIKATA ◽  
TOMOHIRO MIKI ◽  
GO TAKAYAMA ◽  
JUNICHI MOCHIHIRA ◽  
HIROSHI INADA ◽  
...  
Keyword(s):  
Continuous Monitoring ◽  
Todarodes Pacificus ◽  
Common Squid ◽  
Japanese Common Squid
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