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BFAR: New fish kill likely due to low oxygen level at Taal Lake

June 21, 2011 4:41pm
The Bureau of Fisheries and Aquatic Resources (BFAR) on Tuesday warned of a possible new wave of fish kill at the Taal Lake due to the low level of oxygen there.

Esmeralda Paz Manalang, officer-in-charge of BFAR-Calabarzon, said they found out that the level of "dissolved oxygen" — or oxygen beneath the lake — was "very low" off the towns of Agoncillo, Laurel, San Nicolas, and Talisay, all in Batangas.

Talisay is the town most affected by the recent fish kill incidents, with 895 metric tons of fish affected.

The lowest oxygen level as of Tuesday noon was recorded at 1ppm (parts per million) in San Nicolas and 2.27 ppm in Laurel. The ideal oxygen level for bangus (milkfish) farming in areas like the Taal lake is 6ppm.

"As such, BFAR anticipates fish mortalities to occur in these areas," said Manalang in a statement.

As a pre-cautionary measure, Manalang advised fish farmers to: 1) conduct an emergency harvesting of their fish stocks that are already in their "harvestable sizes;" and 2) move their fish cages over to areas with higher oxygen levels.

A technical team has already been deployed to monitor the situation in the area, while a quick-reaction team has been tasked to properly dispose dead fish and prevent them from reaching the market as double-dead meat or "botcha."

The Department of Agriculture has already lent 50 of its pumps to improve "water aeration" at the lake.

Fish kill losses

Estimates by the National Disaster Risk Reduction and Management Council (NDRRMC) earlier showed the fish kill in Batangas and Pangasinan caused at least P184.666 million (1,925 metric tons) in losses.

The NDRRMC said the fish kill affected some 62 fish cage operators (23 in Batangas, 39 in Pangasinan) and 447 fish cages (339 in Batangas, 108 in Pangasinan).

The fish kill prompted authorities in Metro Manila to keep watch against unscrupulous vendors mixing the tainted fish with fresh catch in markets.

Agriculture officials earlier said overstocking may have led to the massive fish kill in Batangas. The ideal size for fish cages is 10 by 10 meters with a depth of six meters, but some cages in the area are 15 meters deep. Fingerlings, meanwhile, should be from 30,000 to 50,000 per cage, but some cages have 100,000.

BFAR officials said there are four factors in a fish kill: Oxygen depletion, pollutant toxin, natural toxins, and disease from bacteria. — KBK, GMA News
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