More than 100 metric tons of tilapia and milkfish or “bangus” died in Taal Lake in Batangas after the July 1, 2021 eruption of Taal Volcano, the Bureau of Fish and Aquatic Resources (BFAR) reported Tuesday, July 6.
BFAR-4A Regional Director Sammy A. Malvas said 109 metric tons of bangus and tilapia worth P8.999 million were killed during the latest fish kill in Talisay, Batangas.
Officials were quick to rule out the Taal volcano eruption as a possible cause of the mass die-off. “There is no direct link between sulfur emissions from the Taal volcano and a decrease in dissolved oxygen levels in the lake,” the regional official said.
According to the latest water quality assessment of Lake Taal dated July 5, dissolved oxygen (DO) levels in some areas, such as Tanauan and Talisay, were 2.38-3.80 milligrams per liter (mg/L), well below the standard 5.0 mg/L level for dissolved oxygen.
In addition, levels of ammonia (0.12-0.21 mg/L) and sulfide (0.01-0.10 mg/L) were also “above standard levels harmful to fish.”
What about acidifying the water?
According to Malvas, the only possible consequence of the Taal volcano eruption is the acidification of its waters. But water quality analysis results show that’s not the case:
“As of yesterday, the water in Taal Lake was not acidic. It remains alkaline or basic. The water is not acidic, so there is no direct link between the sulfur from the volcano and low dissolved oxygen levels,” the official explained.
Amid reports of mass fish kills in Taal Lake in Bulkan Taal, some divers made an underwater video showing the active degassing of the lake floor.
