The humble Tawilis is famous for being the only Sardinella fish to live entirely in freshwater, and it can only be found in Taal Lake. Surrounding towns and cities consider the tawilis a staple food, and tourists love them deep-fried and served with Batangas bulalo.
But all good things come to an end—and in this case, it was an abrupt one. A cursory Google search on tawilis as an endangered species yields a slew of news articles that echoed public panic in the wake of a reassessment of the fish’s status by the Switzerland-based International Union for the Conservation of Nature (IUCN) in October 2018.
Before then, news on the endangerment of the tawilis had been few and far between, even after multiple warnings from the scientific community.
Despite moderate progress being made via recently imposed fishing regulations, there has been pushback from people who depend on the lake for their livelihood.
In the brine-soaked hands of a handful of scientists lay the full story of the tawilis, as well as the key to its survival— tale of declining catch, pollution, wanton fishing, and careless human development.
The advocacy of scientists
“The catch was dwindling, and fish size was smaller and thin,” Augustus C. Mamaril of the UP Diliman Institute of Biology, quotes general observations from the lakeside town as far back as the 1990s. He raised the alarm on the lake which has been a field demonstration and specimen collection site for his Biology class since the late 1980s.
His motivations for proposing the translocation of tawilis to Lake Lanao in northern Mindanao in 1997 were scientific as well as sentimental: he was inspired by the all-out assistance extended by the late Raymundo Punongbayan, director of the Philippine Institute of Volcanology and Seismology.
“Tawilis and practically all of the Taal biota, including a highly venomous marine snake, are the end product, or captives, of a violent volcanic eruption in geologically recent times,” Mamaril says. “The organisms are of marine origin. There was a time when sharks swam in Taal!”
Maria Theresa Mercene-Mutia of the National Fisheries Research and Development Institute (NFRDI) points to declining catch, observed through at least 20 years’ worth of research dating back to the 1990s. Initial exploitation rates were contributed by studies published in 1996 by the Southern Tagalog Integrated Agricultural Research Center, led by Leah Villanueva.
Mutia, a UP Los Baños alumna, was a research assistant of the Taal Lake pioneer environmental scientist, Dr. Macrina Zafaralla, also of UP Los Baños. Mutia serendipitously found herself assigned to a biological station in Taal, Batangas, when she worked for BFAR in the early 1990s. Her immersive devotion to the study of the lake fisheries led to a love for the town, which she has since called home. Her work now forms the backbone of most studies on the tawilis.
She is not alone in her work. Before 1991, the spawning characteristics of tawilis were studied by a BFAR team headed by Simeona Aypa; and around 1999, aspects of its reproductive biology were further researched by Alicia Ely Joson-Pagulayan, a UP Diliman alumna currently with the University of Santo Tomas. In 2008, Rey Donne Papa of the University of Santo Tomas looked into the fish’s diet, which mostly consists of tiny floating zooplankton animals. Papa has put together a team of UST-based researchers to further research Taal zooplankton. In 2011, a team from the UP Diliman Institute of Biology, headed by Jonas Quilang and Brian Santos, did a DNA analysis of the tawilis.
All of these studies provided much-needed data for the environmental planners responsible for the Taal Volcano Protected Landscape (TVPL). Sadly, despite numerous public consultations and symposia, the scientists’ recommendations fell on deaf ears.
The serendipity of red-listing
Then in 2017, their published works were used as the bases for the IUCN assessment that red-listed the tawilis. Mudjekeewis Santos, the principal author, said that the IUCN report merely reiterates the work and advocacy of the Filipino scientists.
Santos, a UP Baguio alumnus and a National Academy of Science and Technology Academician, belongs to the same institution as Mutia. The co-authors of the IUCN assessment include BFAR’s Francisco Torres, a Fisheries alumnus of UP Diliman, and Quilang of the UP Diliman Institute of Biology. They came together during the formation of the Philippine Aquatic Red-List Committee in early 2017.
“By law, we were late [in convening the committee] by seven years or eight years,” Santos adds.
As the Philippine point person for Clupeidae, the family of sardines, Santos headed the assessment of its Philippine species. And this he coordinated with the IUCN global assessment group, which had also been set for sardines. He and his IUCN colleagues had earlier ascertained the marine origins of the tawilis.
The international and local initiatives came together at the 2017 conference in Siargao. The local assessment of the tawilis, being found nowhere else in the world, thus came to inform the global assessment. This prompted the IUCN to include the tawilis in its red list. It recognized “the very small extent of occurrence of tawilis as it is endemic to Taal Lake and evidence of population decline of up to 50 percent in the past 20 years due to numerous threats such as overfishing, pollution, invasive species, habitat degradation, among others,” Santos says.
The resulting public interest has prompted more attention in the national management of resources, but scientists realize this is simply not enough. Policy, implementation, and the cooperation of all stakeholders are essential to saving the species and its ecosystem.
Sustaining the science of conservation
A manager such as Atty. Maria Paz Luna of the Department of Environment and Natural Resources Region IV-A, a UP Diliman alumna who heads the TVPL, says interventions can only be credible through the support of scientific data and consultation with stakeholders.
“There is nothing like speaking with the scientists directly. Without them helping us in the management plan, the status of Taal Lake would have been worse,” Luna said in a conference as she asked for more studies.
With the tawilis red-listing by the IUCN, other freshwater scientists have found a common rallying point. Francis Magbanua of the UP Diliman Institute of Biology, the interim president of the Philippine Society for Freshwater Science (PSFS), said in its advocacy for Taal Lake and tawilis that these are just two of many threatened freshwater bodies and fauna in the country.
Its first summit after its two Symposia on Freshwater Biodiversity and Ecosystems was the Tawilis Summit 2019 in UST. The managers of TVPL, local government officials, the aquaculture and fishing industry representatives came to meet with scientists and researchers, giving each other feedback on what still needed to be known. Specific measures endorsed by the scientists were proposed.
“So many threats exist. Somehow they were lessened in recent years, but still the numbers have not yet shown any increase,” Mutia, the chief tawilis counter of the country, worriedly says.
The IUCN red-listing was a much needed boost to the humble tawilis’ plight; but until studies reveal a sustained revival of the fish population, scientists’ work is far from over.