Death of 800 tonnes of fish in a lake south of Manila. (Photo: YouTube/nocommenttv)
800 tonnes of fish die on fish farms
Tuesday, May 31, 2011, 23:50 (GMT + 9)
A sudden drop in temperature leading to oxygen depletion may have caused the death of 800 tonnes of fish in a lake south of Manila. The fish began to rot last week.
The fish are being buried in Talisay and three other towns in Batangas province. Selling the fish has been prohibited, said Rose del Mundo of the Bureau of Fisheries and Aquatic Resources (BFAR).
The fish mortalities are said to be unrelated to recent signs of activity in the small Taal volcano near the lake, where many villagers have farmed milkfish and tilapia.
On Monday, government volcanologist Allan Loza said magma might be emerging within the volcano, as 115 earthquakes were felt in Taal in the previous 24 hours, compared to an average of 10-15 daily earthquakes in recent weeks. Officials have been detecting similar activity since April, at which point no fish deaths were reported, informs Associated Press.
An initial investigation showed the mortalities may have been due to the shift in temperature. The rainy season began last week following very high temperatures and caused a sudden drop in water temperatures, which exhausted the lake's oxygen levels, according to Talisay agricultural officer Zenaida Macatangay.
The Department of Environment and Natural Resources (DENR) is warning aquaculture farmers to refrain from feeding their fish excessively, as this can help trigger fish kills. Chronic fish deaths of this kind in Taal Lake and elsewhere signal the need for better aquaculture practices, DENR said, as excess fish feeds sink to the bottom, rotting and polluting the water and depleting it of dissolved oxygen (DO), which the fish needs to survive.
“Drastic reduction of DO, which is the oxygen in water, will cause fish kills,” DENR Secretary Ramon Paje said.
Prior to the deaths, the schools of fish were observed swimming in circles. In the past, deaths occurred at summer's end but in much lower quantities.
"Many were sad and devastated because they invested a lot in these fish cages," told Talisay Mayor Zenaida Mendoza.
More than 400 tonnes of milkfish died in Talisay alone between Friday and Monday in 84 out of about 1,000 fish pens, with another 400 tonnes perishing in other towns. Losses are estimated at USD 770,000, Mendoza said.
By Natalia Real