''Sardinella tawilis'' (the freshwater sardinella, freshwater herring, bombon sardine or freshwater sardine) is a freshwater

sardine Sardine and pilchard are common names for various species of small, oily forage fish in the herring suborder Clupeoidei. The term "sardine" was first used in English during the early 15th century; a somewhat dubious etymology says it com ...

found exclusively in the

Philippines The Philippines, officially the Republic of the Philippines, is an Archipelagic state, archipelagic country in Southeast Asia. Located in the western Pacific Ocean, it consists of List of islands of the Philippines, 7,641 islands, with a tot ...

. It is the only member of the genus ''

Sardinella ''Sardinella'' is a genus of fish in the family Dorosomatidae found in the Atlantic, Indian and Pacific Oceans. They are abundant in warmer waters of the tropical and subtropical oceans. Adults are generally coastal, schooling, marine fish but ...

'' known to exist entirely in fresh water. Locally, they are known in Filipino 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 distin ...

international catalogue of endangered heritage foods of

Philippine cuisine Filipino cuisine is composed of the cuisines of more than a hundred distinct Ethnic groups in the Philippines, ethnolinguistic groups found throughout the Philippines, Philippine archipelago. A majority of mainstream Filipino dishes that comp ...

by the Slow Food movement. In January 2019, the

International Union for Conservation of Nature The International Union for Conservation of Nature (IUCN) is an international organization working in the field of nature conservation and sustainable use of natural resources. Founded in 1948, IUCN has become the global authority on the stat ...

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 ...

, 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, ''

''.

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 anterio ...

. 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 Taal Lake (, ), formerly known as Bombón Lake, is a fresh water Volcanic crater lake, caldera lake in the Provinces of the Philippines, province of Batangas, on the island of Luzon in the Philippines. The lake fills Taal Volcano, a large volc ...

in the

Batangas Batangas, officially the Province of Batangas ( ), is a first class province of the Philippines located in the southwestern part of Luzon in the Calabarzon region. According to the 2020 census, it has a population of 2,908,494 people, making ...

province A province is an administrative division within a country or sovereign state, state. The term derives from the ancient Roman , which was the major territorial and administrative unit of the Roman Empire, Roman Empire's territorial possessions ou ...

on the island of

Luzon Luzon ( , ) is the largest and most populous List of islands in the Philippines, island in the Philippines. Located in the northern portion of the List of islands of the Philippines, Philippine archipelago, it is the economic and political ce ...

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 volcanic eruption. An eruption that ejects large volumes of magma over a short period of time can cause significant detriment to the str ...

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 stream of fresh water that flows on land or inside Subterranean river, caves towards another body of water at a lower elevation, such as an ocean, lake, or another river. A river may run dry before reaching the end of ...

. 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 The photic zone (or euphotic zone, epipelagic zone, or sunlight zone) is the uppermost layer of a body of water that receives sunlight, allowing phytoplankton to perform photosynthesis. It undergoes a series of physical, chemical, and biological ...

filter feeder Filter feeders are aquatic animals that acquire nutrients by feeding on organic matters, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a s ...

, 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 (living in the water column), some are benthos, benthic (living on the sedimen ...

s, supplemented with

rotifer The rotifers (, from Latin 'wheel' and 'bearing'), sometimes called wheel animals or wheel animalcules, make up a phylum (Rotifera ) of microscopic and near-microscopic Coelom#Pseudocoelomates, pseudocoelomate animals. They were first describ ...

s and

water flea The Diplostraca or Cladocera, commonly known as water fleas, is a superorder of small, mostly freshwater crustaceans, most of which feed on microscopic chunks of organic matter, though some forms are predatory. Over 1000 species have been recog ...

s. During the summer months when the density of smaller copepods were much higher, their stomach contents consisted primarily of calanoid 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.

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 ( ; ), officially the Province of Cebu (; ), is a province of the Philippines located in the Central Visayas region, and consists of a main island and 167 surrounding islands and islets. The coastal zone of Cebu is identified as a ...

, 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. Given name Mishnaic and Talmudic periods * Jose ben Abin * Jose ben Akabya *Jose the Galilean * Jose ben Halaft ...

used three dried ''tawilis'' in his novel ''Noli Me Tangere'' to symbolize the Three Martyred Priests of Bagumbayan ( Jose Burgos,

Jacinto Zamora Jacinto Zamora y del Rosario (August 14, 1835 – February 17, 1872) was a Catholic Church in the Philippines, Filipino Catholic Priesthood in the Catholic Church, priest, part of the Gomburza, a trio of priests who were falsely accused of muti ...

and Mariano Gomez).

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 stocks, fish stock), resu ...

. 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 an inventory of the global conservation status and extinction risk of biological ...

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; ), 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 in the province of Laguna, some 65 kilo ...

's Limnological Station.

Sources

* *

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 fish of the Philippines Freshwater fish of the Philippines Fish described in 1927 Taxa named by Albert William Herre