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| Local authorities said that a natural disaster caused the mass fish deaths on the La Ngà River in Đồng Nai Province on May 20. — VNA/VNS Photo Lê Xuân |
Viet Nam News
ĐỒNG NAI — Đồng Nai Province plans to offer VNĐ10 billion (US$438,115) to fish farmers affected by mass fish deaths on the La Ngà River caused by a natural disaster two weeks ago.
The province’s People’s Committee said it was providing assistance under a decree which calls for aid for farmers in case of losses caused by natural disasters and epidemics.
More than 1,500 tonnes of dead fish were found on the La Ngà River in the province’s Định Quán District on May 20. Many fish have continued to die.
Most of the dead fish belonged to farmers in the district’s La Ngà and Phú Ngọc communes. Most were lăng fish (hamibagrus), diêu hồng fish (read tilapia) and chép fish (carp).
Huỳnh Thành Vinh, director of the province’s Department of Agriculture and Rural Development, said an investigation was launched immediately after the incident.
Samples of river water and dead fish were collected for tests, while agencies inspected suspicious waste discharged from businesses located upstream from where the deaths occurred.
Based on test results, scientists at the HCM City-based Research Institute for Aquaculture No 2 and the Centre for Environmental Monitoring and Analysis said the losses were caused by discharged waste water from businesses.
Analysis showed that the decline of dissolved oxygen content caused the fish to die.
The concentration of dissolved oxygen in the river water was between 2.6 mg/l to 3.2 mg/l, but the required ratio was 4 mg/l.
The test also found an unusual level of NH4 (Ammonia), 5.6-11 times higher than normal, while NO2 (Nitrite) was 10-20 times higher than the allowable levels for fish farming.
A heavy rainfall prior to the incident possibly carried a large volume of water polluted with garbage and compounds from upstream. In combination with NH4 and NO2, this also contributed to the fish deaths.
In addition, the high density of fish and the narrow distance between cages reduced the volume of oxygen in the living environment of the fish, the local authorities said. — VNS
