Green turtle and fish identification based on acoustic target strength

(1) Sunardi Sunardi Mail (Universitas Ahmad Dahlan, Indonesia)
(2) Azrul Mahfurdz Mail (Sultan Ahmad Shah Polytechnic, Malaysia)
(3) * Shoffan Saifullah Mail (Universitas Ahmad Dahlan, Indonesia)
*corresponding author


Fisherman accidently caught sea turtles in their fishnet. It could be dangerous for its population. This study measures the turtle target strength (TS) using modified echosounder. The result could be used to improve the efficiency of turtle repellent device. The experiment conducted in a hatchery fiber tank contained saline water. The Green were 1, 3, 12 and 18 years old. The study used three species of fish to ensure there are no overlapped value between fish and sea turtle. TS of the animals were calculated incorporating reference targets (sphere). The echo power of the turtle was compared with the solid steel sphere which is confirmed good agreements with the theoretical values. The echo power reference by applying Fast Fourier Transform (FFT) analysis has been used in calculating TS of the animal. From the echo evaluation in time domain at different angles, it is obviously shown that echo signal structure is different between the parts of turtle body. This study reveals that high echo strength is acquired from the carapace and the plastron parts the finding also showed that there are significant differences between 3, 12, 18 years old turtles and fish in every angle measurement.


Target Strength (TS); Green Turtle; Echo Power; Fast Fourier Transform (FFT); Acoustic Measurement



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