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''Sardinella tawilis'' (the freshwater sardinella, freshwater herring, bombon sardine or freshwater sardine) is a freshwater sardine found exclusively in the
Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...
. It is the only member of the genus '' Sardinella'' known to exist entirely in fresh water. Locally, they are known in
Filipino Filipino may refer to: * Something from or related to the Philippines ** Filipino language, standardized variety of 'Tagalog', the national language and one of the official languages of the Philippines. ** Filipinos, people who are citizens of th ...
as ''tawilis''. ''S. tawilis'' is listed in the
Ark of Taste The Ark of Taste is an international catalogue of endangered heritage foods which is maintained by the global Slow Food movement. The Ark is designed to preserve at-risk foods that are sustainably produced, unique in taste, and part of a distinct ...
international catalogue of endangered
heritage foods Heritage Foods Limited (commonly known as Heritage Foods) is one of the largest private sector dairy enterprises in Southern India. History The Heritage Group was founded in 1992 by Telugu Desam Party Chief and former Chief Minister of Andhr ...
of Philippine cuisine by the Slow Food movement. In January 2019, the
International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN; officially International Union for Conservation of Nature and Natural Resources) is an international organization working in the field of nature conservation and sustainable use of natu ...
declared ''S. tawilis'' an endangered species.


Etymology and taxonomic history

''Sardinella'' is the diminutive of the Greek ''sarda'', meaning literally "little sardine". The species was originally identified and named in 1927 as ''Harengula tawilis'' by
Albert William Herre Albert William Christian Theodore Herre (September 16, 1868 – January 16, 1962) was an American ichthyologist and lichenologist. Herre was born in 1868 in Toledo, Ohio. He was an alumnus of Stanford University, where he received a Bachelor of S ...
, the Chief of the Fisheries Division of the Bureau of Science in Manila. The species was later moved to the more appropriate and taxonomically accurate genus, '' Sardinella''.


Description

''S. tawilis'' is a small fish reaching up to 15 cm and weighing less than 30 g. Like other members of their family, they have laterally compressed bodies with bellies covered in tough, scale-like
scutes A scute or scutum (Latin: ''scutum''; plural: ''scuta'' "shield") is a bony external plate or scale overlaid with horn, as on the shell of a turtle, the skin of crocodilians, and the feet of birds. The term is also used to describe the anterior po ...
. They have a single, triangular dorsal fin and a forked caudal fin. They possess long, slender gill rakers in their mouths.


Range and distribution

''S. tawilis'' populations are only found in Taal Lake in the
Batangas Batangas, officially the Province of Batangas ( tl, Lalawigan ng Batangas ), is a province in the Philippines located in the Calabarzon region on Luzon. Its capital is the city of Batangas, and is bordered by the provinces of Cavite and La ...
province A province is almost always an administrative division within a country or sovereign state, state. The term derives from the ancient Roman ''Roman province, provincia'', which was the major territorial and administrative unit of the Roman Empire ...
on the island of
Luzon Luzon (; ) is the largest and most populous island in the Philippines. Located in the northern portion of the Philippines archipelago, it is the economic and political center of the nation, being home to the country's capital city, Manila, as ...
in the Philippines. Taal Lake is the third-largest lake in the Philippines and is located in the
caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...
of an ancient volcano. It has an area of about and lies at nine municipalities and two cities. Near its center lies the Volcano Island which has a crater lake in the middle. The lake has a maximum depth of and an average depth of . Before recent history, the lake was but an extension of the entirely marine Balayan Bay, connected by a channel that narrowed through time and transpired as a
river A river is a natural flowing watercourse, usually freshwater, flowing towards an ocean, sea, lake or another river. In some cases, a river flows into the ground and becomes dry at the end of its course without reaching another body of wate ...
. Major eruptions in the 18th century essentially sealed the lake from the sea, eventually leading its waters to become fresh water. ''S. tawilis'' is believed to be one of a few former marine species trapped within the lake that have evolved into purely freshwater species.


Ecology

''S. tawilis'', like members of its family, is an epipelagic
filter feeder Filter feeders are a sub-group of suspension feeding animals that feed by straining suspended matter and food particles from water, typically by passing the water over a specialized filtering structure. Some animals that use this method of feedin ...
, using its gill rakers to strain plankton from the water while it swims with its mouth open. They roam the lake in large schools, just below the surface as the volcanic (and thus sedimentary) nature of the lake limits their plankton food to the surface. The freshwater sardinella prefers to ingest larger prey, such as adult
copepod Copepods (; meaning "oar-feet") are a group of small crustaceans found in nearly every freshwater and saltwater habitat (ecology), habitat. Some species are planktonic (inhabiting sea waters), some are benthos, benthic (living on the ocean floor) ...
s, supplemented with
rotifer The rotifers (, from the Latin , "wheel", and , "bearing"), commonly called wheel animals or wheel animalcules, make up a phylum (Rotifera ) of microscopic and near-microscopic pseudocoelomate animals. They were first described by Rev. John H ...
s and
water flea The Diplostraca or Cladocera, commonly known as water fleas, are a superorder of small crustaceans that feed on microscopic chunks of organic matter (excluding some predatory forms). Over 1000 species have been recognised so far, with many more ...
s. During the summer months when the density of smaller copepods were much higher, their stomach contents consisted primarily of
calanoid Calanoida is an order of copepods, a group of arthropods commonly found as zooplankton. The order includes around 46 families with about 1800 species of both marine and freshwater copepods between them. Description Calanoids can be distinguis ...
copepods, which are larger than the copepods blooming during this time. This suggests some partial control over prey selection exhibited by the fish, as opposed to simple filter-feeding. Little is known about their reproduction. It is known that the Taal population spawns during the months of April to July, when surface temperatures are highest. The reproduction of the species saw a decline after the
eruption of Taal Volcano in 2020 Several types of volcanic eruptions—during which lava, tephra (ash, lapilli, volcanic bombs and volcanic blocks), and assorted gases are expelled from a volcanic vent or fissure—have been distinguished by volcanologists. These are often ...
.


Importance to humans

Despite its threatened status, stocks in Lake Taal have been commercially fished for several decades. The fish is a widely popular food fish in the Philippines, and tons are shipped to most of the major cities in the country. Local supermarkets and wet markets usually have a tray or pile dedicated solely to the species. The species is commonly referred to as ''tawilis'' in the local language of Tagalog. On the island of
Cebu Cebu (; ceb, Sugbo), officially the Province of Cebu ( ceb, Lalawigan sa Sugbo; tl, Lalawigan ng Cebu; hil, Kapuroan sang Sugbo), is a province of the Philippines located in the Central Visayas region, and consists of a main island and 167 ...
, one of the many places where ''tawilis'' is shipped, the native Cebuano name for the fish is ''tunsoy''. In addition to raw consumption, ''tawilis'' is also processed into various food products. It is one of the many fish species dried, salted, and sold as ''daing'' in the country. They are also smoked and bottled in oil, and sold commercially. In literature,
Jose Rizal Jose is the English transliteration of the Hebrew and Aramaic name ''Yose'', which is etymologically linked to ''Yosef'' or Joseph. The name was popular during the Mishnaic and Talmudic periods. * Jose ben Abin * Jose ben Akabya *Jose the Galile ...
used three dried ''tawilis'' in his novel ''Noli Me Tangere'' to symbolize the Three Martyred Priests of Bagumbayan (
Jose Burgos Jose is the English transliteration of the Hebrew and Aramaic name ''Yose'', which is etymologically linked to ''Yosef'' or Joseph. The name was popular during the Mishnaic and Talmudic periods. * Jose ben Abin * Jose ben Akabya *Jose the Galile ...
, Jacinto Zamora and
Mariano Gomez Mariano Gomez or Mariano Gómez may refer to: * Mariano Gomez (priest) Mariano Gómes de los Ángeles (), often known by his birth name Mariano Gómez de los Ángeles, was a Filipino Catholic priest, who was falsely accused of mutiny by the ...
).


Conservation

Because of several factors, the species is threatened by
overfishing Overfishing is the removal of a species of fish (i.e. fishing) from a body of water at a rate greater than that the species can replenish its population naturally (i.e. the overexploitation of the fishery's existing fish stock), resulting in th ...
. As with all species consisting of a single population in one location, a local extinction event will lead to species extinction. As the population of the Philippines grows, the demand will be greater for ''tawilis'', possibly overfishing the lake's stock population. According to the
IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...
report which conducted last 28 February 2017 and published in 2018, the catch of the ''tawilis'' started to decline since 1998 due to overfishing, illegal use of active fishing gears, increasing use of fish cages, and the deterioration of the water quality in Taal Lake. The harvest of the ''tawilis'' has said to declined by at least 50 percent over the past 10 years. Because of this, the IUCN listed the ''tawilis'' as endangered. In February 2021, some ''tawilis'' were taken out of Taal Lake due to Taal Volcano's increasing volcanic activity. The conservation project led and funded by the Department of Science and Technology's Council for Agriculture, Aquatic, and Natural Resources Research and Development resettled the ''tawilis'' at
University of the Philippines Los Baños The University of the Philippines Los Baños (UPLB; fil, Unibersidad ng Pilipinas Los Baños), also referred to as UP Los Baños or colloquially as Elbi (), is a public research university primarily located in the towns of Los Baños and Bay ...
's Limnological Station.


Sources

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References


External links


"Born to be Wild: Tawilis"
on GMA News Online (2008_0313) {{Taxonbar, from=Q3753916 tawilis Commercial fish Taal Lake Fauna of Luzon Endemic fauna of the Philippines Freshwater fish of the Philippines Fish described in 1927 Taxa named by Albert William Herre