Spatial distribution characteristics analysis and resources assessment of fish in Lugu Lake

From August 15 to 19, 2018, we assessed the spatial distribution and resources of fish in Lugu Lake, Yunnan Province for the first time by using lowrange elite-7 Ti echo detector. Zigzag route was used to detect the whole Lugu Lake, with a total voyage of 42.71 km. Based on the depth variation value, the lake was divided into a number of detection units for fish resources evaluation, and the spatial distribution map was drawn based on the density of each unit by inverse distance weighting (IDW). The results of hydroacoustic survey shows that the spatial distribution of fish in Lugu Lake was uneven. In the horizontal direction, most fish clusters were distributed in the coastal annular waters, among which the fish density in the waters near Xiaoyuba was the highest, while the fish density in the middle of the lake was the lowest; in the vertical direction, the fish distribution in the surface waters was relatively concentrated. In August 2018, the fish density in Lugu Lake was 0.153·(1 000 m³)⁻¹; the total number of fish was 243 900 and the total resource was 50.55 t (Carassius auratus: 211 700 ind., total mass of 17.36 t; Cyprinus carpio: 17 400 ind., total mass of 23.01 t; Ctenopharyngodon idellus: 86 300 ind., total mass of 8.63 t; Paramisgurnus dabryanus: 6 800 ind., total mass of 1.33 t; Schizothorax microstomus: 700 ind., total mass of 0.22 t). In this survey, there was no records of S. ninglangensis and S. labrosus which had been found in previous investigation.