Effects of Noise and Absorption on High Frequency Measurements of Acoustic-Backscatter from Fish

Figure 1

Noise power spectrum level (dB re 1 μPa²/Hz) relevant to acoustic surveys of fish resources. Heavy rain (100 mm/h) noise [11], snapping shrimp noise [12], vessel self-noise of RV “Hokko-maru” (220-tonne steel ship at a speed of 11 knots) [8], vessel self-noise of RV “Soyo-maru” (892-tonne noise-reduced ship at a speed of 10 knots) [9], wind-induced noise at rough sea (sea state 6) [13], and sea thermal noise (water temperature 10°C) [10] are shown.