The trophic status and estimation of fish potential production in Batur Lake, Indonesia: A preliminary study

Lake Batur is a type of volcanic lake in Bangli Regency, Bali, Indonesia. The main problems in Lake Batur are no outlet, organic matter pollution from accumulated waste from the human population, cages, and agriculture. This study intends to investigate and evaluate the existing trophic status, the condition of the water, and fish production potential in Batur Lake. Observations were conducted at six stations in March 2023 using random purposive sampling. The status of water was calculated using the Trophic State Index (TSI), and fish yield was estimated using the Morphoedaphic Index (MEI). The findings showed that the TSI measurements of Batur Lake ranged from 54.07 to 75.25. In this condition, the lake is categorized as eutrophic. The annual fish production potential ranges from 109.9 to 210.5 kg/ha, with an average of 120.4 kg/ha. With 1600 hectares, the lake can produce 109-130 tons of fish. Based on captured fisheries statistic data in 2022, the potential value of fish production was relatively lower than the fishery production, which amounted to 576 tons. To suggest sustainable fisheries in Batur Lake, we need to maintain the existing fishing regulations and keep stabilizing the water quality.