http://www.gmanews.tv/story/110572/Fish-ki...n-Batangas-town BATANGAS CITY, Philippines – A fish kill struck in Taal Lake, destroying at least 124.12 metric tons of tilapia and bangus worth P8.5 million in Agoncillo town, the Bureau of Fisheries and Aquatic Resources–Inland Fisheries Research Station (BFAR–IFRS) said Thursday.
In its partial report, the BFAR-IFRS said the fish kill occurred on Sunday and Monday affecting around 100 fish cages in Subic Ilaya village.
Most of the affected tilapia stocks were already on harvestable size while the smaller ones survived, aquaculturist Maribel Carolino of the Provincial Agriculture Office said. .
Carolino however said that the actual damage to local fishing communities might be higher since the provincial fishery staff has yet to survey other affected areas in the lake like Laurel town.
BFAR–IFRS aquaculturist Maurita Rosana said that fish kills are already common in Taal Lake particularly in the months of May to July, when heavy rains start to fall.
"As early as June, she said that the BFAR is already expecting a fish kill due to the traces of hydrogen sulfide but typhoon Frank prevented it by diluting the lake's waters," Rosana told GMANews.TV in an interview.
In the following weeks, however, she said that the rain stopped and this created favorable conditions for hydrogen sulfide to grow and multiply in the lake.
The said chemical, which was detected at high levels in July 22, is being produced through decomposition of organic matters in the lake such as uneaten fish feeds, fish feces and domestic wastes that accumulate at the bottom waters.
Rosana likewise said that the fishes might have died of suffocation due to the toxic gas emissions of hydrogen sulfide, which depleted the lake's oxygen supply.
The BFAR–IFRS also admitted that that improper aquaculture practices by local operators in the lake such as intensive feeding and overstocking of tilapia fry in fish cages had caused this week's fish kill.
Although the agency recommends just 30,000 to 50,000 tilapia fries per cage, Rosana said operators sometimes stock up to 400,000 fries per cage to meet their quota.
While fish kills are natural events, she also believes that man can help prevent its impact by practicing environmentally-sound aquaculture.
"We cannot control the natural processes that spread the nutrients in the lake but by following the recommended cage stocking density and feeding practices, we could reduce the number of nutrients that trigger pollutants in the lake," she added.
Taal Lake, which has a surface area of 234.2 square kilometers, is the country's third largest lake next to Laguna and Lanao Lake.
It was declared a protected area through the National Integrated Protected Areas System Act by virtue of Presidential Proclamation 906. - Marlon Luistro, GMANews.TV