Fish in cages in Hai Duong died due to lack of oxygen, not disease

After receiving information about dead fish in cages, the Department of Agriculture and Rural Development of Hai Duong province coordinated with the Departments of Fisheries, Veterinary, Aquaculture Research Institute I (under the Ministry of Agriculture and Rural Development), and the Department of Natural Resources and Environment to conduct field inspections, assign technical staff to closely monitor, grasp the situation, and determine the cause of fish deaths.

From April 1-4, the Department of Agriculture and Rural Development conducted rapid sampling at locations where fish died in cages in Tien Tien, Nam Dong, Ngoc Chau wards (Hai Duong city); Binh Lang, Dai Son, Ha Ky, Ha Thanh communes (Tu Ky); Nhan Hue, Co Thanh wards and communes (Chi Linh); Nam Tan, Thai Tan communes (Nam Sach); Thanh Hai, Thanh Son, An Phuong communes (Thanh Ha). The results showed that the dissolved oxygen (DO) content in the water was very low, only 2-3 mg/l while the allowable standard is 5 mg/l. The toxic gas content was high, exceeding the allowable threshold. In addition, at some locations, fish were infected with parasites and mold.

According to the announcement of the Department of Natural Resources and Environment, the quick measurement results on April 7 at some points on the Thai Binh River (Hai Duong City area) showed that the dissolved oxygen content in the water ranged from 0.83-1.11 mg/l, lower than the standard. The quick measurement results on April 8 at the Thai Binh River in Nhan Hue Commune (Chi Linh), the end point of the Duong River flowing into the Thai Binh River, Pha Lai Bridge, the point at the Bac Hung Hai system before flowing into the Thai Binh River in Quang Trung Commune (Tu Ky) and at the Thai Binh River section through Dai Thang Commune, Tien Lang District flowing towards Hai Phong showed that the dissolved oxygen content in the water at the locations ranged from 3.09-3.88 mg/l, lower than the standard. Particularly, the sample at the Bac Hung Hai system section through Quang Trung Commune (Tu Ky) before flowing into the Thai Binh River, the dissolved oxygen content in the water reached 6.34 mg/l, exceeding the allowable standard.

Through inspection and analysis of factors, the Department of Agriculture and Rural Development determined that the cage fish died not due to disease but due to lack of oxygen.

The Department recommends some immediate solutions to limit damage. These include increasing oxygenation measures such as aeration, water stirring, cage cleaning, etc. and preventing fish diseases. Reduce fish density in cages, promptly consume fish that have reached size, and thin out healthy fish in high-density cages. Focus on collecting, processing, and destroying dead fish, not letting dead fish into the environment to limit environmental pollution and the risk of disease outbreaks. Provide electricity for production.

According to statistics from districts, cities and towns, as of April 9, the number of dead fish in Hai Duong province is estimated at more than 950 tons.

Previously, from March 28-29, fish in cages in Tien Tien commune (Hai Duong city) had scattered deaths, poor appetite, and lethargic swimming. From March 30 to April 4, the temperature suddenly increased, and fish died sporadically in cage fish farming areas such as Nam Dong (Hai Duong city), Nhan Hue, Co Thanh (Chi Linh), Nam Tan, Nam Hung, An Binh, Cong Hoa, Hiep Cat, Thai Tan (Nam Sach), Dai Son, Binh Lang, Ha Ky (Tu Ky), Thanh Hai, An Phuong (Thanh Ha). Particularly in Tien Tien commune (Hai Duong city), the damage was more severe.

From April 5-7, fish deaths continued to occur sporadically at the above-mentioned farming locations and also occurred at some new locations such as An Son, Minh Tan (Nam Sach), Ha Thanh, Nguyen Giap (Tu Ky), Thanh Son, Thanh Hong (Thanh Ha), Van An, Dong Lac (Chi Linh), Hong Phong, Ninh Giang town (Ninh Giang), Thang Long, An Phu (Kinh Mon), Duc Chinh (Cam Giang), Phuc Thanh (Kim Thanh). By April 9, the number of fish deaths in cages had decreased, with insignificant numbers.