Species Identification and Tempo-Spatial Distribution of Anchovy Using Multi-Frequency

In this study, we identified the echo signals of anchovies on echograms using the dB-difference method; additionally, the daytime and nighttime distribution characteristics of anchovies were determined. Using the difference in frequency characteristics of 18, 38, 70, 120, and 200 kHz, the dB-difference intervals of -2.1 dB <= Delta MVBS18-38 <= 4.4 dB, -9.7 dB <= Delta MVBS70-38 <= 1.3 dB, -10.2 dB <= Delta MVBS120-38 <= 2.3 dB, and -10.7 dB <= Delta MVBS200-38 <= 0.3 dB were set to extract the echo signals of anchovies. The results revealed that anchovies showed a relatively higher distribution in the coast than in the open sea. In February, the average density of anchovies was observed to be 3.43 g/m2, whereas in May, it was observed to be 6.02 g/m2. Also, anchovies were found to be mainly distributed at 30-70 m water depths during the day, and at 30-50 m water depths during the night.