Los Baños, Laguna—Sec. Acosta, Presidential Adviser for Environmental Protection and concurrent Laguna Lake Development Authority General Manager, personally visited the areas affected by the recent fishkills in the municipalities of Pakil, Pangil, and the city of Calamba in Laguna and in Jalajala, Rizal.
Investigations revealed that species affected were tilapia, big head carp, knife fish and kanduli. As of May 29, 2012, the damage cost has risen to Php 1,382,500, affecting 1,500 fishcages and 20 fishpens.
Sec. Acosta was joined by Director Asis Perez of the Department of Agriculture -Bureau of Fisheries and Aquatic Resources (DA-BFAR), who later met with local officials of Laguna and fisherfolk representatives to discuss areas of cooperation and complementation.
Quick Response Teams (QRT) have been dispatched in key areas of the lake to monitor any indication of fishkill. Three units of patrol boats from BFAR were deployed and shall be manned by the members of the Fish Health monitoring group and QRTs. The joint task force shall respond to fish kill situations, undertake water quality monitoring and provide early warnings to prevent the escalation of fishkill.
It is suspected that the sudden change in weather conditions from hot summer to rainy season might have caused the fishkill. When it rains, the surface water temperature goes down and in turn forces the hot water beneath to rise. This also causes the decomposing elements at the bottom of the lake to rise and compete with fish for oxygen.
Further, during an onset of heavy rains, a “river flushing” occurs wherein pollutants and wastewater from rivers are “flushed” into the lake. Here, heavy wave action and re-suspension of sediments cause pollutive agents such as garbage and wastewater to reach and contaminate the lake water.
On-site water sample analysis was made on three parameters: dissolved oxygen (DO), temperature and pH level. The DO level is found to be adequate and passed the minimum requirement of 5 milligrams per liter (mg/L). At that time, water temperature is pegged at 25 degrees Celsius while water pH level is within the normal range of 6.5-8.5 units. However, the monitoring group stressed that the levels might have been different during the exact time of fishkill (when the rains started pouring in).
Incidentally, the tilapia and the kanduli were found to be overly feeding on the liya(green algae). The greenish appearance of the water suggests an algal bloom which is typical at this time of the year when the weather changes from hot to wet season.
Sec. Acosta is asking the fishpen operators and the fisherfolks to be vigilant and to cooperate with the government so as to minimize, if not prevent, the occurrence of fishkills. Early harvesting of fish is also encouraged to evade an imminent fishkill and to avoid overcrowding of fish in the pens. As for the proper management of dead fish, the LLDA and the BFAR suggest that the waste be properly disposed into controlled dumping locations. After decomposition, these can be turned into beneficial fertilizer.