Ex situ and in situ measurements of juvenile yellowfin tuna Thunnus albacares target strength

Lu, Hang; Kang, Myounghee; Huang, Hsing-Han; Lai, Chi-Chang; Wu, Long-Jin

doi:10.1007/s12562-011-0401-4

Cited by 8 publications

(2 citation statements)

References 25 publications

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“…Target strength (TS) is a key parameter used to identify species in the echogram and convert the echo signal into biomass. TS varies between species and is affected by many factors including swim bladder characteristics (Foote, 1980), body size (Lu et al, 2011), swimming pitch angle (Horne, 2003), water depth (Mukai and Iida, 1996), and incident sound wave frequency (Foote, 1982). Therefore, it is very important to correctly identify target species, estimate their TS, and understand the factors that affect TS variation to accurately assess stocks of marine fish.…”

Section: Introductionmentioning

confidence: 99%

Impacts of Morphological Characteristics on Target Strength of Chub Mackerel (Scomber japonicus) in the Northwest Pacific Ocean

et al. 2022

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Chub mackerel (Scomber japonicus) is an important commercial fish in the Northwest Pacific Ocean. Accurate target strength (TS) underpins acoustic stock assessment but the TS of S. japonicus is still poorly understood. In this study, the Kirchhoff-ray mode (KRM) model was used to estimate the TS of S. japonicus and its relationship with sound wave frequency and fish morphology. The results revealed that TS values varied with pitch angle shifts, with the impact on fish scattering strength being greater at higher frequency. This is less important because 38 kHz has been used for the biomass assessment of these fish resources. At frequencies of 38 kHz, 70 kHz, 120 kHz and 200 kHz, TS was greatest at a pitch angle range of -10° to 0°, which was related to the angle of the swim bladder tilt. There were almost no differences between TS estimated using the measured pitch angle distributions and using the universal distribution. When the measured pitch angle was N[-3°,4°], the average TS of S. japonicus with body length of 12.04–22.17 cm at four frequencies was -48.88 dB, -49.14 dB, -49.75 dB and -48.55 dB, respectively. The regression intercept (b20) in TS–body length equation was -73.27 dB, -73.56 dB, -74.18 dB and -73.46 dB, respectively. Variation in TS range at 0–300 m depth was about 10 dB. The simulated broadband target strength spectrum shows the scattering characteristics of individuals with different swim bladder length between 0–250 kHz. These results could be used for identification of S. japonicus in echograms and provide reference for acoustic stock assessment of S. japonicus in the Northwest Pacific Ocean.

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Section: Introductionmentioning

confidence: 99%

Impacts of Morphological Characteristics on Target Strength of Chub Mackerel (Scomber japonicus) in the Northwest Pacific Ocean

et al. 2022

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“…A common approach to overcome the limitations of optical sensors is to combine them with other kinds of sensors such as a camera with a laser [22,23], a camera with LiDAR [24], or a camera with an acoustic sensor [1,6]. In the particular application of fish biomass estimation, cameras have been previously combined with acoustic sensors in [25][26][27][28][29][30]. Electronic devices need power to function, and even more so if the scene needs to be illuminated by some source of light.…”

Section: Introductionmentioning

confidence: 99%

Automatic Bluefin Tuna Sizing with a Combined Acoustic and Optical Sensor

Muñoz-Benavent

Puig-Pons

Andreu-Garcı́a

et al. 2020

Sensors

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A proposal is described for an underwater sensor combining an acoustic device with an optical one to automatically size juvenile bluefin tuna from a ventral perspective. Acoustic and optical information is acquired when the tuna are swimming freely and the fish cross our combined sensor’s field of view. Image processing techniques are used to identify and classify fish traces in acoustic data (echogram), while the video frames are processed by fitting a deformable model of the fishes’ ventral silhouette. Finally, the fish are sized combining the processed acoustic and optical data, once the correspondence between the two kinds of data is verified. The proposed system is able to automatically give accurate measurements of the tuna’s Snout-Fork Length (SFL) and width. In comparison with our previously validated automatic sizing procedure with stereoscopic vision, this proposal improves the samples per hour of computing time by 7.2 times in a tank with 77 juveniles of Atlantic bluefin tuna (Thunnus thynnus), without compromising the accuracy of the measurements. This work validates the procedure for combining acoustic and optical data for fish sizing and is the first step towards an embedded sensor, whose electronics and processing capabilities should be optimized to be autonomous in terms of the power supply and to enable real-time processing.

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Estimation of Bluefin Tuna (Thunnus thynnus) mean length in sea cages by acoustical means

et al. 2022

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Ex situ and in situ measurements of juvenile yellowfin tuna Thunnus albacares target strength

Cited by 8 publications

References 25 publications

Impacts of Morphological Characteristics on Target Strength of Chub Mackerel (Scomber japonicus) in the Northwest Pacific Ocean

Impacts of Morphological Characteristics on Target Strength of Chub Mackerel (Scomber japonicus) in the Northwest Pacific Ocean

Automatic Bluefin Tuna Sizing with a Combined Acoustic and Optical Sensor

Estimation of Bluefin Tuna (Thunnus thynnus) mean length in sea cages by acoustical means

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