The cause of the mass death of fish in cages on the Nghen River in Ha Tinh was determined to be due to many unsuitable water parameters in the fish farming area.
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| Authorities took water samples from the area where dead fish were raised in cages for analysis. Photo: TAN KY |
On October 10, information from the Department of Fisheries of Ha Tinh province said that this unit had the results of water sample analysis to determine the cause of mass deaths of fish raised in cages on Nghen river in Thach Son commune (Thach Ha district, Ha Tinh).
According to the analysis results of the Northern Center for Environmental Monitoring and Aquatic Diseases (under the Aquaculture Research Institute 1), the indicators including temperature, DO, pH, COD, N-NH4+, N-NO2-, H2S, P-PO43... all have values within the allowable limits according to Vietnamese standards. However, the indicators: pH, salinity, alkalinity... have values that are not suitable for fish farming.
"Salinity and alkalinity at the sampling points were both low. Total iron content was also higher than the standard. Algae density ranged from 50,720 - 192,425 cells/liter and no toxic algae were detected," the analysis concluded.
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| Fish raised in cages in Thach Son commune died en masse due to many unsuitable water parameters. Photo: PHAM DUC |
From the above results, the Northern Center for Environmental Monitoring and Aquatic Diseases believes that low salinity, low alkalinity and high total iron content are unsuitable conditions for cage-cultured fish to grow and develop.
In particular, high iron content is the cause of hindering the respiratory process of fish and causing toxicity. In addition, low pH values can also increase the toxicity of heavy metals.
To remedy the situation of dead fish, the Ha Tinh Province Fisheries Department requested local authorities to inspect and handle water environment factors where fish cages are located in Thach Son Commune. At the same time, temporarily suspend fish farming activities at this time to implement measures to handle the water environment.
Previously, on the morning of October 6, people in Song Hai village (Thach Son commune) visited the cages of sea bass and red snapper on Nghen river and discovered the fish floating sluggishly on the water surface. Shortly after, almost all of the fish cages of 53 households died, with a total of more than 50 tons, causing an estimated loss of several billion VND.
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