Previously, fish in Song May Lake started dying around April 22nd and began dying in large numbers on April 28th. The fish died in large numbers, floating white on a large area of the lake’s surface. The stench spread over a wide area, as far as the residential area around the lake, affecting people’s lives. The dead fish were mainly Tra fish, bighead carp, tilapia, and other types of catfish.
THE CAUSE OF THE HUNDREDS OF TONS OF DEAD FISH
On May 3rd, 2024, a delegation from the Department of Agriculture and Rural Development of Dong Nai province went to inspect the handling of dead fish at Song May Lake, Trang Bom district. The inspection was to investigate the cause of the fish die-off and the environmental treatment at Song May Lake.
The initial investigation determined that the massive fish die-off was due to low water levels in the lake, causing the lake bed to dry up. At the same time, the stocking density of fish in the lake was high, so the fish were deprived of oxygen, resulting in a mass die-off.
Specifically, the surface area of Song May Lake at the time of the dam’s peak elevation was nearly 196.6 hectares, but at the time of the fish die-off, the surface area was only about 2 hectares, and the water depth was shallow. The deepest point was only about 1m above the lake bed.
During the same period every year, Song May Lake still had about 4-5 million m3 of water for the summer-autumn crop. However, this year, due to the renovation and repair of Song May Lake, the water level in Song May Lake was drained more than in previous years.
Over the past period, Song May Lake has had to prioritize water release for irrigation and aquaculture in the winter-spring season, with an area of about 800 hectares in Trang Bom and Vinh Cuu districts. The dry season this year was severe, with intense heat, prolonged drought, and no rain for a long time, resulting in a loss of water replenishment to the lake from natural streams and rainwater, causing a massive fish die-off.
Song May Lake has an area of over 300ha and is located in Trang Bom district. It is a reservoir that provides irrigation water for hundreds of hectares of rice in Trang Bom and Vinh Cuu districts. Since 1994, Dong Nai province has assigned the provincial Military Command to raise aquatic products on the water surface.
Over the past period, the aquaculture activities on Song May Lake have been carried out under a contract between the Dong Nai Provincial Military Command and the One Member Limited Liability Company of Exploit Water Resources Construction of Dong Nai Province (Dong Nai Water Resources Company).
In early January 2024, the One Member Limited Liability Company of Exploit Water Resources Construction of Dong Nai Province began implementing the Song May Lake renovation and repair project, which required lowering the water level to create a construction site. The company had widely announced the news so that units and people could plan their aquaculture activities accordingly, including a request to harvest the fish in the lake before December 31st, 2023, to hand over the construction site to the project contractor on schedule.
When the water level in the lake decreased, combined with factors such as drought, heat, no water replenishment, and high fish density, the oxygen in the water became insufficient, and the fish began to die.
COMPLETION OF THE COLLECTION OF DEAD FISH AND THE TREATMENT OF ENVIRONMENTAL POLLUTION AFFECTING PEOPLE’S LIVES
According to the records, the fish started dying around April 22nd and began dying in large numbers on April 28th. According to the aquaculture unit, these were not new fish that had been released this year but fish that had been in the lake since the end of 2023.
After receiving the notice about the Song May Lake renovation project, the aquaculture unit did not release any new fish for this year’s season. This was the remaining stock from the previous year, and the fish were not large enough, weighing only 1-2 ounces each, and were not of sufficient size to be sold.
Speaking to the press, a representative of the aquaculture team said that this year, the drought and heat in the area had been prolonged, with little rain, resulting in low water levels and a large number of fish remaining in the aquaculture unit’s stock. In addition, the dam construction project and the dredging of Song May Lake’s bottom sediment had caused a loss of oxygen, leading to a massive fish die-off, with nearly 200 tons of Tra fish, bighead carp, silver carp, common carp, tilapia, etc.
To deal with the massive fish die-off, the unit mobilized forces to collect the fish and transport them to lime pits to make bio-fertilizer. They also spread lime throughout the area to reduce the stench that was affecting people.
The representative of the aquaculture team said that over the past few days, the unit had mobilized all cadres, soldiers, and staff to continuously collect and bring the dead fish from Song May Lake to the shore to minimize environmental pollution. By the afternoon of May 2nd, 2024, the collection of dead fish carcasses on the lake had been completed.
The fish were used by the unit as raw material for composting into organic bio-fertilizer. After completing the collection of dead fish carcasses in Song May Lake, the authorities immediately implemented environmental treatment measures, such as spreading lime to remove the stench and disinfect the lake area.
The environmental treatment of Song May Lake is of utmost importance to ensure the environment and water source for aquaculture and to carry out flood discharge tasks to ensure flood prevention and control in 2024.
Speaking to VnEconomy about the drought’s impact on production and livelihood, Dr. Le Anh Tuan, Faculty of Environment and Natural Resources, Can Tho University, commented that the fish deaths during this season in the lake are usually caused by heat, drought, and decreased water levels in the lakes, leading to a lack of oxygen in the water. Especially during the dry season, when the heat is intense, in many places, record temperatures are broken, water evaporates quickly, and the oxygen in the water is rapidly depleted, while the high density of fish can lead to fish deaths. This is also a common phenomenon during the dry season and heat.
When fish die in large numbers, as in Song May Lake, it can cause environmental pollution and affect the lives of people living in the surrounding area. With such a large number of dead fish, they can be collected and processed into organic fertilizer.
Dr. Tuan added that provinces like Dong Nai will face drought and freshwater shortages during this season, while provinces in the Mekong River Delta will face the biggest natural disaster, which is the saltwater intrusion.
