On 11/9, commercial clam farmers in Ngoc Son ward were hiring machinery and workers to collect dead clam shells for disposal. Along the over two-kilometer stretch of coastline, a strong fishy odor emanated from the decomposing clam carcasses, intensified by the hot weather.

According to residents, the unusual clam deaths began in late August and have not subsided. The Ngoc Son ward People's Committee reported that 50 out of 78 farming households have been affected, impacting an area of approximately 60 hectares.

Clams cover the intertidal flats along the coast in Ngoc Son ward. *Photo: Lam Son*

The dead clams, sized at about 150-160 individuals per kilogram, were not yet ready for harvest. Mortality rates in some concentrated farming areas reached up to 80%, with total estimated losses ranging from 2,000 to 2,400 tons.

Specialized units from the Department of Agriculture and Environment collected samples for testing to determine the cause. According to the initial assessment by the agricultural sector, the clam deaths are attributed to the effects of Typhoon Narra and prolonged heavy rainfall. A large volume of freshwater from upstream flowed into the lower Yen River, carrying silt and waste that covered the farming beds, causing a rapid decrease in salinity, shocking and weakening the clams.

Monitoring results on 28/8, after the storm and when the clam deaths began, showed that the salinity in the farming area of Ngoc Son ward was only 8,6 parts per thousand, approximately one-third of the normal level. In contrast, national standards for aquaculture water stipulate a suitable salinity for clam farming of about 20-35 parts per thousand.

Specialized agencies are awaiting test results to fully determine the cause, while also guiding residents on how to manage the affected farming areas, prevent water pollution, and minimize the risk of impact on neighboring areas.

Clam mortality density reached over 80% in some spots. *Photo: Lam Son*

The agricultural sector encourages households to harvest commercial-sized clams early to mitigate losses. For smaller clams, residents are advised to thin out overcrowded areas, clean the farming beds daily, and monitor the clams' condition to implement appropriate measures.

The Ngoc Son ward People's Committee also recommends that residents temporarily suspend releasing new clam batches until the farming environment is treated and meets required standards.

Thanh Hoa province currently has over 1,000 hectares of commercial clam farming, concentrated in tidal areas such as Van Loc, Tan Tien, Hoang Thanh, and Ngoc Son, with an estimated annual output of 20,000 tons.

Le Hoang