Acoustic Target Strengths and Swimbladder Morphology of Chub Mackerel <i>Scomber japonicus</i> in the Northwest Pacific Ocean
The Northwest Pacific chub mackerel (<i>Scomber japonicus</i>) is one of the most productive, economically important fishery resources worldwide. Accurately assessing this species and ensuring adherence to total allowable catch limits are crucial owing to fluctuations in their abundance...
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| Main Authors: | , , , |
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| Format: | Article |
| Language: | English |
| Published: |
MDPI AG
2024-09-01
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| Series: | Journal of Marine Science and Engineering |
| Subjects: | |
| Online Access: | https://www.mdpi.com/2077-1312/12/9/1500 |
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| Summary: | The Northwest Pacific chub mackerel (<i>Scomber japonicus</i>) is one of the most productive, economically important fishery resources worldwide. Accurately assessing this species and ensuring adherence to total allowable catch limits are crucial owing to fluctuations in their abundance and distribution. Acoustic target strength measurements of <i>S. japonicus</i> were conducted at 38, 70, and 120 kHz using a split-beam echosounder of individuals from nine size groups (mean fork length, 10.8–28.3 cm) swimming freely in a net cage within a seawater tank. An underwater camera was utilized to simultaneously measure swimming angle. Least-squares regression analysis revealed that when the slope was constrained to 20, as per the generally applicable morphometric equation, the resulting values for the constant term (<i>b</i><sub>20</sub>) were −67.7, −66.6, and −67.3 dB at 38, 70, and 120 kHz, respectively. <i>S. japonicus</i> mean swimming angle across the groups was −10.5–9.6° (standard deviation [SD], 16.3–33.3°). Furthermore, the ratio of swimbladder height to swimbladder length, the ratio of swimbladder length to fork length, and the tilt angle of the swimbladder (mean ± SD) were 0.191 ± 0.060, 0.245 ± 0.055, and 9.6 ± 3.0°, respectively. These results can be used for the acoustic stock assessment of <i>S. japonicus</i> in the Northwest Pacific Ocean. |
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| ISSN: | 2077-1312 |