MANILA, Philippines - About 500 metric tons of fish drowned for lack of oxygen in Taal Lake in Batangas on Saturday, the Department of Environment and Natural Resources (DENR) said yesterday.
DENR Secretary Ramon Paje told The STAR underwater vegetation consumed the oxygen that milkfish (bangus) and tilapia needed to survive.
Marine life can drown if deprived of oxygen, he said.
He explained that fish feed can end up in the lake bed and become fertilizer for vegetation.
Underwater vegetation would decompose and increase the biological oxygen demand, he added.
Fisheries official Rose del Mundo said initial investigation showed that temperature change as the rainy season set in after a scorching summer had depleted Taal Lake’s oxygen levels.
The die-off started last week in Lake Taal in Talisay and Laurel in Batangas, she added.
The lake’s surface in areas cordoned off for farming is packed with rotting milkfish, Del Mundo said.
Paje said fishkill also happens in Taal Lake and other lakes in Luzon because too many fish cages obstruct the water flow.
Thirty percent of Taal Lake is already occupied by fish cages, he added.
Paje said fish must be released into the lake without being caged so they can breed freely.
Paje said decongesting lakes must be taken within the next months.
The number of fish cages in the lakes must be regulated, he added.
DENR representatives are already in Batangas to look into the massive drowning of the bangus and tilapia, Paje said. – With AP