BFAR (Region 4-A) Regional Director Esmeralda Paz Manalang said sulfur upwelling in the Taal Lake triggered the fish kill in barangays Aya, Quiling, Tumaway and Sampaloc in Talisay, Batangas late last week.
The fish kill affected 51 of 2,000 fish cages in Talisay town, killing 70 tons of bangus and 50 tons of tilapia, reports ABS.CBN.
Manalang said the phenomenon was caused by the lake’s “overturn” and a possible sulfur upwelling brought about by the northeast monsoon.
An overturn happens as cool water at the top of the lake becomes heavier and goes down, while warm water rises to the surface, he explained. This process causes sulfur and other organic matter on the lake bottom to rise and affect the fish in the cages, he added.
BFAR has been keeping an eye on the phenomenon, which is caused by the wind disturbing the sediments in the lake and releasing hydrogen sulfide since 2000.
Arlan Garcia, local chief of Brgy. Sala in Balete, Batangas, said that various fish species were found “gasping for air” along the shoreline of the said town in the evening of January 16 and blue-green discoloration was reported in the water off barangays Aya, Quiling, Tumaway, and Sampaloc.
BFAR director Asis Perez said fish cage operators were advised early that sulfur upwelling is more likely to happen in the cold months between November and February.
“Fish cage operators have also been advised to conduct emergency harvest of marketable sizes of tilapia and bangus,” Perez said
Water pumps have also been issued to operators to increase the dissolved oxygen in the water, which has reached critical levels, Perez said
Meanwhile, members of the Taal Lake Aquaculture Alliance Inc. (TLAAI), Task Force Taal Lake, the Department of Environment and Natural Resources (DENR), the LGUs, and the BFAR will make sure fish affected by the phenomenon will not reach the market and proper disposal will be implemented.
Based on BFAR records, Taal lake has an allowable 6,000 fish cages with an estimated aquaculture production of 54, 000 metric tons and an equivalent value of P4.05 billion annually.
