TANAUAN CITY — The Bureau of Fisheries and Aquatic Resources (BFAR) has again asked fish cage operators in Taal Lake to harvest their existing tilapia stocks to avoid a fish kill.
A fish kill could be caused by the lowering of the dissolved oxygen level in the water because of the congestion inside the fish cages.
In an advisory on June 13, BFAR Regional Director Esmeralda Paz D. Manalang said their agency’s Inland Fisheries Research Station has recorded low levels of the lake’s dissolved oxygen (DO) in three sampling stations namely Sampaloc, in Talisay town; Balakilong and Berinayan in the town of Laurel.
The official said that the onset of a rainy season brought about a sudden drop in water temperature, which led to the sudden drop of the lake’s DO, adding that the alternating wind directions of southeasterly wind “salatan” and the northeasterly wind “amihan,” and the southwest monsoon “habagat,” have contributed to the lake’s poor water quality in the past days.
The normal DO level is 6 parts per million (ppm), but the latest findings in June 13 showed that the DO level have dropped to 3.31 ppm in Sampaloc; 4.40 ppm in Berinayan and 4.35 ppm in Balakilong.
It was also reported that last June 9, a 2.49 ppm DO level in Barangay Bañaga in Agoncillo town caused some fish to float lifeless.
While fish kills are natural occurrences, the BFAR earlier admitted that irresponsible aquaculture practices such overstocking and overfeeding tilapia stocks in the cage also contribute to fish kills.
The big bulk of unconsumed feeds and fish feces that settles at the lake’s bottom waters deplete the lake oxygen as they decompose.
While the agency recommends that a fish cage operator must stock only 30,000 to 50,000 tilapia fingerlings in a cage, the operators usually exceed the limit in order to meet their quota.
It can be recalled that in September 28, 2011, typhoon Pedring had destroyed 52.7 metric tons of bangus and tilapia fish worth P3.8 million in Agoncillo alone.
The BFAR also reported that in May 30, 2011 the fish kill damaged about 750 metric tons of tilapia in the lake worth about P57 million, affecting the cage areas of Agoncillo, Laurel, Talisay, San Nicolas and Mataas na Kahoy.
Taal, which has a surface area of 24,356 square meters, is the world’s third largest lake next to Laguna and Lanao Lakes. It was declared a protected area in 1996 through the National Integrated Protected Areas System Act, by virtue of Presidential Proclamation 906.
In 2012, the Supreme Court has issued a writ of kalikasan stopping the issuance of new clearances for fish cages in Taal Lake.
The high tribunal ordered the Protected Area Management Board (PAMB) to refrain from issuing clearances for fish cage operations in the popular lake in Batangas. This was in response to an earlier petition by the party-list group Agham asking the Supreme Court to issue a writ of kalikasan to force government to support efforts to protect Taal Lake and stop the issuance of licenses to operators of fish pens in the lake.
In a 19-page petition, Agham Rep. Angelo Palmones said the government failed to implement the Philippine Fisheries Code and the National Integrated Protected Areas System law in the lake.
These laws call for the phase-out of fish cages and fish pens after the year 2000.
Palmones said that in 1927, the fish inventory of Taal Lake listed 76 migratory and endemic species, but 50 years later, the inventory was down to 15. In 2003, the catch of tawilis, the most popular endemic fish species from Taal, dropped by 80 percent.
Last year’s fishkill in Taal that led to a loss of 2,105 metric tons of fish with an estimated value of P148.7 million was a loud wake up call, he said.
Palmones said one of the factors that led to the fishkill was the failure of government to enforce existing environmental laws.
Photo by PNEJ member, EV ESPIRITU.