On September 11, in an exchange with a reporter from Lao Dong Newspaper, Mr. Le Dinh Phuong - Vice Chairman of Ngoc Son Ward People's Committee, Thanh Hoa province confirmed that in recent days, mass clam deaths have occurred in the area at people's farms.
According to the People's Committee of Ngoc Son ward, on September 4, the locality received information reflecting from people about the phenomenon of mass clam deaths.
Immediately after that, the ward established a delegation to go to the field to inspect and grasp the situation, and at the same time report the incident to the Department of Agriculture and Environment of Thanh Hoa province.
Upon receiving the information, the Department of Agriculture and Environment directed the Sub-Department of Livestock and Veterinary Medicine, the Sub-Department of Sea and Islands and Fisheries to assign officials to coordinate with the People's Committee of Ngoc Son ward to conduct field inspections, take water samples and clam samples for testing to determine the cause.
According to the results of field inspection, reports from the People's Committee of Ngoc Son ward and reflections from farming households, the phenomenon of clam deaths occurred on about 60ha of farming grounds of 50 households. Clams are about 150-160 heads/kg in size, with a death rate of about 80%.
The phenomenon of clam deaths began to appear from August 26, when storm No. 4 caused heavy rain, and the amount of fresh water poured into the river mouth area increased. By the time of inspection, clams continued to die.
The clam density at the inspected farming sites is about 850-880 clams/m2, 4-5 times higher than the recommended level. The estimated clam death output is from 2,000-2,400 tons.
The Sub-Department of Livestock and Veterinary Medicine, the Sub-Department of Sea, Islands and Fisheries in coordination with the People's Committee of Ngoc Son ward took 3 water samples and 3 clam samples for testing to determine the cause.
According to the Thanh Hoa Department of Agriculture and Environment, initial assessments show that the phenomenon of clam death may be related to the impact of storm No. 4. During this time, prolonged heavy rain occurred in the area, the amount of fresh water from upstream pouring into the estuary area where clams are raised was very large, leading to a rapid decrease in salinity, causing clams to be shocked and affecting their health.
Environmental monitoring results on August 13 showed that the salinity in the area was 25.4‰. By August 28, after the clams began to die and there was a storm, the salinity was only 8.6‰, about 1/3 compared to before.
Meanwhile, according to TCVN 13951:2024 on aquaculture water - seawater - quality requirements, appropriate salinity limits for clam farming belonging to mollusk group from 20-35‰.
Representatives of Ngoc Son Ward People's Committee said that while waiting for test results to determine the specific cause of clam deaths, the locality has requested farming households to urgently collect dead clam carcasses to limit water environment pollution and affect other farming grounds.
People are also instructed to level the beach surface, clear puddles of stagnant water in the farming area, avoid localized water stagnation and limit the impact of high temperatures during the day causing clam weakness and death.
For areas of clams that have reached commercial size, the locality recommends that people urgently harvest to reduce damage. Households with clams that have not reached commercial size need to strengthen care, regularly monitor and clean the farming ground daily.
Ngoc Son Ward People's Committee also proposed to temporarily suspend new farming. Breeding can only be carried out after the environment is treated, the farming ground is renovated, ensuring appropriate conditions for clams to grow and develop.
