Fish kill warning up in Taal Lake

SUNSET FISHING A fisherman in Taal Lake works at sunset to bring food to his family in the lakeshore town of Mataas na
Kahoy in Batangas province. —REM ZAMORA

SAN PEDRO CITY, Laguna, Philippines — Fisheries officials on Wednesday warned of a possibility of a fish kill in Taal Lake due to the “poor quality” of water recently tested in two lakeshore towns in Batangas province.

The Bureau of Fisheries and Aquatic Resources (BFAR) in Calabarzon (Cavite, Laguna, Batangas, Rizal and Quezon) region said the shifting wind direction from the northeast and southeast was causing the current water condition, putting thousands of fish cages at risk.

Low oxygen

Tilapia growers were advised to keep monitoring their cages and begin harvesting fully grown or “marketable” stocks so they could recover part of their investment.

The water’s dissolved oxygen level, a parameter used to check whether the water remained favorable to aquaculture, continued to drop below the normal level of 6 milligrams per liter, according to a series of BFAR advisories since Monday.

On the other hand, high concentrations of ammonia (0.21 mg/L to 0.33 mg/L) and sulfide (0.31 mg/L to 1.83 mg/L) described to be “harmful” to the fish, were also recorded breaching the normal levels of 0.2  g/L and 0.002 mg/L, respectively.

The BFAR said the poor water quality was recorded in the villages of Bañaga, Bilibinwang and Manalaw in Agoncillo town and in Barangay Leviste and Buso-Buso in Laurel town.

For instance in Barangay Bañaga, the dissolved oxygen was down to as low as 0.20 mg/L on Wednesday, from 1.73 mg/L on Monday.

The BFAR also advised fish cage owners to take measures by installing oxygen tanks and pumps to augment the declining oxygen level.

Taal Lake is home to about 6,000 tilapia cages scattered in several parts of the water body. In June, about 600 metric tons of tilapia, estimated at P42.9 million worth of investments, were lost to a fish kill.—MARICAR CINCO