February 12, 2025
JAKARTA – The Maritime Affairs and Fisheries Ministry has launched an investigation into a mass mortality event that affected thousands of fish at floating fish farms at the Jatiluhur Dam, Purwakarta Regency, West Java, over the weekend.
Officials from the ministry’s Directorate General of Fish Farming, along with personnel from the Purwakarta Animal Husbandry and Fisheries Agency, visited the dam on Monday to collect water samples for analysis.
The ministry’s Director of Freshwater Fish Farming Ujang Komarudin estimated that approximately 100 tonnes of fish were lost in the incident, the majority of which were goldfish.
“Given that the price of goldfish is around Rp 22,000 (US$1.34) per kilogram, this mass die-off has led to an estimated loss of around Rp 2.2 billion for the fish farmers,” he said on Monday, as reported by Antara.
Although the cause of the incident is still under investigation, Ujang suggested that the mass fish die-off was likely caused by extreme weather conditions and a natural phenomenon known as upwelling.
Upwelling occurs when changes in wind direction affect the lake’s currents, causing deeper waters to mix with those at the surface. This phenomenon can lead to oxygen depletion for fish living near the surface, as deeper waters typically have lower oxygen levels.
Fish farmers at the Jatiluhur Dam reported several days of heavy rain and strong winds in the area last week, which also contributed to a drop in water temperature, further exacerbating the conditions.
Head of the Farming Department at the Purwakarta Animal Husbandry and Fisheries Agency, Intan Riyani, said that the upwelling phenomenon occurs frequently at the Jatiluhur Dam, particularly during the rainy season.
“Overfishing has further increased the risk of mass fish deaths at the Jatiluhur Dam, as fish feed contributes to pollution in the lake, which has deteriorated the water quality in the reservoir,” Intan said, as reported by Tribunnews.
She noted that there were currently around 44,000 floating fish farms at the Jatiluhur Dam, far surpassing the ideal number of 11,300 units. Her agency is actively working to reduce the number of fish farms in the reservoir.
Intan also noted that the ministry had issued warnings to farmers since November of last year, advising them to harvest their fish early. However, many farmers opted to wait for their fish to grow larger instead.
In response to last week’s mass fish die-off, the Maritime Affairs and Fisheries Ministry has urged farmers at the Jatiluhur Dam to harvest all of their fish, particularly goldfish, as they are highly sensitive to changes in dissolved oxygen levels.
The ministry has also advised farmers to temporarily suspend fish farming activities until the weather improves and water quality stabilizes. Additionally, authorities have urged farmers to collect all of the dead fish and dispose of them properly to prevent contamination and pollution of the reservoir.
Extreme weather and strong winds also led to the deaths of thousands of tilapia in fish ponds at Ngebel Lake, Ponorogo Regency, East Java, earlier this month.
The winds triggered an upwelling, bringing sulfuric deposits from the lake’s bottom to the surface, which poisoned the fish and caused millions of rupiah in losses.
Last month, extreme weather also triggered upwelling in floating fish farms at Maninjau Lake, Agam Regency, resulting in the death of around 25 tonnes of tilapia and Rp 625 million in losses.