SAN PABLO CITY – An estimated 12 tons of tilapia, black mask, and silver perch, or “ayungin”, were lost in a massive fish kill in Sampaloc Lake here.

An estimated 12 tons of tilapia, black mask, and silver perch, or “ayungin”, were lost in a massive fish kill in Sampaloc Lake here. (Ali Vicoy / MANILA BULLETIN)

According to fish cage owner Andrea Teodoro, they noticed that some “ayungin” and black mask fish started to surface dead at the lake on January 1.

Then on the next day, Teodoro said tilapia began to float dead on the lake.

Teodoro, who is also the president of the local Fisheries and Aquatic Resources Management Council (FARMC), said fish cage owners tried to harvest whatever fish they could, but they could only salvage some.

In all, she estimated that 13 tons of fish were lost.

Laguna Lake Development Authority (LLDA) Biologist Jonathan Nicolas explained that the fish kill could have been caused by the depletion of dissolved oxygen in the lake, leading to an upwelling or overturn.

Local fishermen call this “duong”, and noted that the natural phenomenon occurs every time the weather becomes colder.

Nicolas said that since water on the surface of the lake was colder, this sinks while sending the water under to the top.

This results in a depletion of dissolved oxygen, leading to the high mortality of the fish population in the lake.

Because of this, Bureau of Fisheries and Aquatic Resources (BFAR) Region 4 Director Sam Malvas said fish cage owners need to harvest whatever they can because the “duong” was likely to last while the cold weather persists.

He underscored that fish that would be harvested alive would still be safe for human consumption.

Ali Vicoy

Tons of tilapia, ‘ayungin’, black mask lost in Sampaloc Lake fish kill