GENERAL SANTOS CITY (MindaNews / 16 Oct) – Around 20 metric tons (MT) of harvestable Tilapia and Pangasius were devastated as another fish kill hit anew some portions of the critical Lake Sebu in South Cotabato in the last three days.
Lake Sebu Mayor Antonio Fungan said Wednesday the fish kill, which was the first incident that occurred in the area this year, has already affected an estimated 60 fish cages situated in parts of three lakeside villages.
He said the fish kill was initially monitored on Monday in portions of Purok Rosas and the main section of Barangay Poblacion.
The mayor said their personnel were still determining the extent of the damage caused by the incident but local fish cage operators initially pegged a loss of nearly P1 million.
Citing their initial assessment, Fungan said the latest fish kill in the area was caused anew by “kamahong,” a phenomenon that is mainly caused by the sudden rise in the water’s temperature.
“It happened after a series of heavy rains along the lake,” he said in a radio interview.
“Kamahong,” which usually occurs during the rainy season, triggers the rise of sulfuric acid in the lake’s waters that eventually caused the massive fish kill, provincial fishery coordinator Rex Vargas earlier said.
“It occurs when cold rainwater, which is heavier than warm water, settles at the abyssal zone of the lake. This causes the water upturn or upwelling of warm water carrying silts, sediments, and gases such as hydrogen sulfide, ammonia, sulfur and methane gas produced by the decomposing organic matter such as fish feeds,” he explained.
Vargas said such situation results in the reduction of dissolved oxygen in the water, “forcing fishes to take in oxygen directly from the atmosphere and eventually die.”
Last year, around 57 MT of Tilapia were destroyed in two fish kills at the lake that were blamed on “kamahong.”
The initial fish kill in January 2012 ravaged some 48.55 MT of Tilapia. It affected 48 fish cage owners and left a total damage of P3.8 million based on tilapia’s market price of P80 per kilo.
In August last year, an additional 8,000 kilograms of Tilapia valued at P650,000 were destroyed in another fish kill that affected 14 fish cages at the lake.
Fungan admitted that the recorded fish kills have worsened in the past several years due to the deterioration of the lake’s condition as triggered by the overcrowding fish cages and the over-utilization of fish feeds.
The municipal government pushed last year for a voluntary dismantling of fish cages in overcrowded portions of the lake but only a few operators heeded the move.
“This time, we’ll make sure that our fish cage operators will cooperate with us because the lake is now very much overcrowded, to the extent that its dissolved oxygen supply could no longer meet their requirements,” he said.
Following twin fish kills last year, the Bureau of Fisheries and Aquatic Resources (BFAR) central office recommended a moratorium on the fish cage operations in Lake Sebu, which it described as already over-polluted and on the brink of devastation.
BFAR also noted that the lake is considered overcrowded with fish cages, which already covered 35 percent of its waters or way beyond the 10 percent allowed by law.
The Department of Environment and Natural Resources earlier placed Lake Sebu’s carrying capacity at around 320 fish cages.
But the lake’s fish cages have so far reached a total of 4,586 or around 13 times beyond its capacity.