By Noreen Jazul
Tawilis (sardinella tawilis) or bombon sardine which is found only in the Philippines has been listed among “endangered” species by the International Union for Conservation of Nature (IUCN).
The international organization, in a 2018 report, listed the freshwater sardine living in Taal Lake as endangered due to the alarming decrease in its population.
IUCN said overexploitation, pollution, and competition and/or predation with introduced fishes were the three major threats to tawilis and fish diversity within Taal Lake which resulted in “continuing declines in habitat quality and number of mature individuals.”
It noted a significant decline in the catches of tawilis since 1998.
“It is estimated that harvest has declined by about 49% over the past 10 years (more than three generation lengths),” the report said.
“Fishing effort using illegal gears which target this species in the lake is increasing, but at this time, the rate of increase has not been quantified specifically, so it is inferred that the population has declined by at least 50% over the past 10 years,” it added.
IUCN reported that the lacustrine species’ habitat, Taal Lake, was subject to “pollution from aquaculture feeds, domestic waste, and unmanaged tourism on the Volcano Island.”
“Aquaculture facilities in Taal Lake have caused habitat destruction and hampered the movement of this species. Competition and/or predation by introduced aquaculture fishes are likely occurring,” the reported stated.
A survey conducted from 1996 to 1999 recorded 27 fish species from 32 families in the lake, which is much lower than records from the 1920s that recorded 101 species from 32 families.
Given this, about 87 percent of fish species had disappeared by 1996, which coincided with the same period that aquaculture began, researchers said.
The group also reported that tawilis was”heavily exploited” from 2008-2009.
Tawilis, the only species of sardinella known to occur exclusively in freshwater, is endemic to Taal Lake.
IUCN said the declining population of Tawilis should be considered a “high” priority for conservation by the Philippine government. (With reports from Ellalyn De Vera-Ruiz)