Climate change takes its toll on Taal Lake fish growers

Batangas tilapia and bangus growers are bracing themselves for bigger losses due to mounting massive fishkills in Taal Lake resulting from a climate change that has raised the toxic sulfur emission in the lake.

The Department of Agriculture quoted initial reports from the municipal agricultural office of Talisay town as saying that the fishkill in Taal Lake has so far destroyed 720 metric tons of tilapia and bangus stocks valued at P50.4 million.

The fishkill has affected almost 80 percent of the total 72 fishcages in the lake, each with an average harvestable stock of 10 metric tons.

In a report to Agriculture Secretary Domingo Panganiban, the Inland Fisheries Research Station (IFRS) of the Bureau of Fisheries and Aquatic Resources (BFAR) said the alternating wind patterns in Taal Lake have greatly influenced the incidence of fishkills in the Talisay area.

These changes in the northeast, southwest and southeast wind patterns have resulted in a distinct vinegar-like coloration of the water in Barangays Aya, Quiling and Tumaway.

The report cited research findings by the FishHealth Team of BFAR-IFRS in Ambulong, Tanauan City that there has been a sulfur upwelling, a natural phenomenon, evidenced by the strong pungent smell of asupre, in the area, causing the massive fishkill.

The report cited other contributing factors such as the congestion of fishcages and high density of tilapia and bangus stocks.

Moreover, physico-chemical analysis showed that the dissolved oxygen level has been depleted, ranging from .9 to 1.5 ppm, while the carbon dioxide level ranged from 9.8 to 12.4 ppm.

These levels of oxygen and carbon dioxide are associated with fishkill occurrences.

The presence of nitrite, ranging from .033 to .165 ppm, is still within permissible levels.

The fishcage operators have been advised to harvest their marketable-sized stocks and not to stock new fingerlings into their cages.

They were also told to follow responsible aquaculture practices such as proper stocking density and feeding management, and to dispose off the dead fish properly.

Since fishkills may also occur in nearby barangays, other municipalities like Laurel, Agoncillo and San Nicolas have been advised to be vigilant and take precautionary measures since the sulfur upwelling, which has come earlier than expected, is still in its peak.

This climate change phenomenon usually occurs between February and April.