Agriculture Business Week

Lake Taal is the third largest lake in the country with an area of 24,000 hectares and average depth of over 100 meters. Once a part of the sea, it is home to the world’s only freshwater sardine, the tawilis (Sardinella tawilis). The species is believed to have become landlocked when the lake (formerly connected to Balayan Bay along the coast of Batangas) was formed through eruptions more than 240 years ago.

The tawilis is a member of the Family Clupeidae of fishes to which the herrings and sardines belong. It is pelagic (surface-dwelling) and related to the marine tunsoy and tam ban (Sardinella albella).

Being a much relished food item, the tawilis is heavily exploited and caught by using various fishing gear. The fresh fish sells for P80-120 per kilo depending on the season. In a survey conducted in 1998-1999, 57 percent of the fishes caught in the lake was tawilis.

Dr. Lourdes Castillo of the University of the Philippines Los Banos’ Institute of Biology reports that the tawilis breeds throughout the year with the peak in March to June. Its sticky eggs are attached to plants and rocks in the periphery of the lake. The fish mainly feeds on zooplankton, minute animals suspended in the water like copepods, rotifers, and cladocerans.

According to fisheries biologists, the tawilis has a life cycle of 15 months and grows to a maximum length of more than 15 centimeters (cm). The juveniles grow at the rate of 2 cm per month and become mature at a length of 7 to 8.5 cm in four months. A female tawilis with a length of 15.2 cm that was sampled has a weight of 27.3 grams.

The Bureau of Fisheries and Aquatic Resources have imposed conservation measures for the sustainable management of the tawilis fishery of surrounding municipalities of Lake Taal, namely, Agoncillo, Balete, Laurel, San Nicolas, and Talisay.

Among the measures are the establishment of a fish sanctuary area and banning the use of motorized push nets (suro) and “superlights” (very strong artificial illumination used to attract the fish at night). Enforcement of such regulations, however, is weak.

In a study for the conservation of the tawilis conducted by Dr. Castillo and her co-workers with support from the Philippine Council for Aquatic and Marine Research and Development of the Department of Science and Technology, it was found that the fish is overexploited in the lake. From the optimum range of 30-50 percent, the fishery was being exploited at 62 percent. They recommended the reduction of fishing pressure to the optimal level, the use of 2.5-centimeter mesh for gill nets, the catch size limit of 10 cm for the fish, the total ban on the use of active fishing gear such as suro, and the strict enforcement of other regulations like the fish sanctuary.