Acoustic Characteristics of Clione Limacina in the Southern Ocean

Abstract

In the Southern Ocean, the biomass of Clione limacina is relatively large in some sea areas, and the largest biological density was found in the survey reached 300 Ind /m3. The acoustic data were obtained from the scientific fish finder (SIMRAD EK60) on Xuelong polar research vessel during China's 32nd Antarctic expedition. The system operated at a frequency of 38 and 120kHz. The acoustic data obtained from the expedition were processed in the specialized software used by the Institute for Underwater Acoustic Survey and Analysis of Biological Resources (ECHOVIEW 6.1.72, MYRIAX, AUSTRILIA). Biological sampling was carried out by using a "Framed Antarctic Krill Resource Assessment with Double capsule trawl". The sampling net is double capsule structure, the network port is frame type, the size is 4 m×2 m, the net capsule net mesh is 15 mm. It was found that the target intensity of Clione limacina in the central Ocean was significantly stronger at 120 kHz, which was 12.97±0.61 dB stronger than 38 kHz in general.