Fish emerge, mass deaths due to hot weather
In early June, the Bac Ha hydropower reservoir area recorded prolonged hot weather, with continuous high temperatures. In the communes along the lake, especially in places where cage fish farming is concentrated, many households are worried when sturgeon rises to the surface, refuses to eat and then dies en masse. The phenomenon of fish deaths appeared from the end of May and has increased rapidly in recent days. Many sturgeon cages have been heavily damaged, some households lost tons of commercial fish preparing for sale.
The initial cause was determined to be prolonged hot weather causing the lake water temperature to rise, and the amount of dissolved oxygen in the water to decrease sharply. Sturgeon is a aquatic species that likes cold water, suitable for temperatures from 18-24 degrees Celsius, so it is very sensitive to weather changes. When the water temperature exceeds the tolerance threshold, the fish are prone to heat shock, reduced resistance and mass deaths.
Some farming households said that no year has the weather been as extreme as this year. In just a few days, the amount of dead fish increased rapidly, making people unable to react in time. Many households are facing the risk of losing hundreds of millions of dong, even billions of dong after many months of investing in seeds, food and care.
Talking to Lao Dong Newspaper, Mr. Dang Xuan Phuong - Chairman of Bao Nhai Commune People's Committee - informed that on the Bac Ha hydropower reservoir, there are currently 24 farming facilities with more than 1,000 fish cages, mainly sturgeon. Up to this point, the volume of dead sturgeon is about nearly 10 tons and the locality has arranged a centralized burial area, disinfecting to prevent diseases and environmental pollution.
Urgently rescue fish, limit damage
After the phenomenon of mass fish deaths appeared, the Sub-Department of Crop Production, Plant Protection and Animal Husbandry, Veterinary Medicine, and Fisheries under the Department of Agriculture and Environment sent specialized officials to directly inspect the scene, determine the cause and guide response measures. Functional forces recommend that farming households regularly monitor water environment developments, reduce farming density in cages with large outputs, and increase water fans and air purification to supplement oxygen.
For affected cages, the Sub-Department guides people to reduce the amount of feed, increase air purification, move cages to deeper water areas (from 2.5 - 3 meters), and harvest early batches of fish that have reached commercial size to limit risks.
Raising sturgeon on Bac Ha hydropower lake for many years has become an important livelihood for hundreds of households. With favorable natural water sources, cage fish farming has developed strongly, creating jobs and bringing stable income to many highland families.
However, in recent years, the impact of climate change has made the weather increasingly unusual. Prolonged heat waves appear with higher frequency, putting great pressure on aquaculture activities, especially for cold-water fish such as sturgeon.
Some farming households said that the investment cost for a sturgeon cage is very large, from seeds, feed to cage systems. Therefore, just a prolonged heat wave can cause the effort and capital accumulated for many months, even years, to be swept away by batches of dead fish.
Faced with the situation of fish deaths on Bac Ha hydropower lake, many farming households proposed that the agricultural and environmental sectors and the Lao Cai Provincial Coldwater Fish Association soon review and support the receipt and transfer of fish from the affected lake area to suitable farming facilities.
People also hope that the industry and trade sector will inspect and request Bac Ha Hydropower Plant to have a plan to operate and regulate water sources reasonably to reduce the impact of hot weather on the farming environment.
