Milkfish
Overview
The milkfish is the sole living species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Chanidae. (About seven extinct
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

 species in five additional genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 have been reported.)
Milkfish have a generally symmetrical and streamlined appearance, with a sizable forked caudal fin. They can grow to 1.7 metre but are most often about 1 metres (39.4 in) in length. They have no teeth and generally feed on algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

 and invertebrates.

They occur in the Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 and across the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

, tending to school
Shoaling and schooling
In biology, any group of fish that stay together for social reasons are said to be shoaling , and if, in addition, the group is swimming in the same direction in a coordinated manner, they are said to be schooling . In common usage, the terms are sometimes used rather loosely...

 around coast
Coast
A coastline or seashore is the area where land meets the sea or ocean. A precise line that can be called a coastline cannot be determined due to the dynamic nature of tides. The term "coastal zone" can be used instead, which is a spatial zone where interaction of the sea and land processes occurs...

s and island
Island
An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...

s with reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....

s.
Encyclopedia
The milkfish is the sole living species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 in the family
Family (biology)
In biological classification, family is* a taxonomic rank. Other well-known ranks are life, domain, kingdom, phylum, class, order, genus, and species, with family fitting between order and genus. As for the other well-known ranks, there is the option of an immediately lower rank, indicated by the...

 Chanidae. (About seven extinct
Extinction
In biology and ecology, extinction is the end of an organism or of a group of organisms , normally a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point...

 species in five additional genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 have been reported.)

Description and biology

Milkfish have a generally symmetrical and streamlined appearance, with a sizable forked caudal fin. They can grow to 1.7 metre but are most often about 1 metres (39.4 in) in length. They have no teeth and generally feed on algae
Algae
Algae are a large and diverse group of simple, typically autotrophic organisms, ranging from unicellular to multicellular forms, such as the giant kelps that grow to 65 meters in length. They are photosynthetic like plants, and "simple" because their tissues are not organized into the many...

 and invertebrates.

They occur in the Indian Ocean
Indian Ocean
The Indian Ocean is the third largest of the world's oceanic divisions, covering approximately 20% of the water on the Earth's surface. It is bounded on the north by the Indian Subcontinent and Arabian Peninsula ; on the west by eastern Africa; on the east by Indochina, the Sunda Islands, and...

 and across the Pacific Ocean
Pacific Ocean
The Pacific Ocean is the largest of the Earth's oceanic divisions. It extends from the Arctic in the north to the Southern Ocean in the south, bounded by Asia and Australia in the west, and the Americas in the east.At 165.2 million square kilometres in area, this largest division of the World...

, tending to school
Shoaling and schooling
In biology, any group of fish that stay together for social reasons are said to be shoaling , and if, in addition, the group is swimming in the same direction in a coordinated manner, they are said to be schooling . In common usage, the terms are sometimes used rather loosely...

 around coast
Coast
A coastline or seashore is the area where land meets the sea or ocean. A precise line that can be called a coastline cannot be determined due to the dynamic nature of tides. The term "coastal zone" can be used instead, which is a spatial zone where interaction of the sea and land processes occurs...

s and island
Island
An island or isle is any piece of sub-continental land that is surrounded by water. Very small islands such as emergent land features on atolls can be called islets, cays or keys. An island in a river or lake may be called an eyot , or holm...

s with reef
Reef
In nautical terminology, a reef is a rock, sandbar, or other feature lying beneath the surface of the water ....

s. The young fry live at sea for two to three weeks and then migrate to mangrove
Mangrove
Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...

 swamps, estuaries
Estuary
An estuary is a partly enclosed coastal body of water with one or more rivers or streams flowing into it, and with a free connection to the open sea....

, and sometimes lake
Lake
A lake is a body of relatively still fresh or salt water of considerable size, localized in a basin, that is surrounded by land. Lakes are inland and not part of the ocean and therefore are distinct from lagoons, and are larger and deeper than ponds. Lakes can be contrasted with rivers or streams,...

s and return to sea to mature sexually and reproduce.

Aquaculture

The milkfish is an important seafood in Southeast Asia
Southeast Asia
Southeast Asia, South-East Asia, South East Asia or Southeastern Asia is a subregion of Asia, consisting of the countries that are geographically south of China, east of India, west of New Guinea and north of Australia. The region lies on the intersection of geological plates, with heavy seismic...

 and some Pacific Islands. Because milkfish is notorious for being much bonier than other food fish, deboned milkfish, called "boneless bangus" in the Philippines, has become popular in stores and markets.

History

Milkfish aquaculture
Aquaculture
Aquaculture, also known as aquafarming, is the farming of aquatic organisms such as fish, crustaceans, molluscs and aquatic plants. Aquaculture involves cultivating freshwater and saltwater populations under controlled conditions, and can be contrasted with commercial fishing, which is the...

 first occurred around 800 years ago in the Philippines
Philippines
The Philippines , officially known as the Republic of the Philippines , is a country in Southeast Asia in the western Pacific Ocean. To its north across the Luzon Strait lies Taiwan. West across the South China Sea sits Vietnam...

 and spread in Indonesia
Indonesia
Indonesia , officially the Republic of Indonesia , is a country in Southeast Asia and Oceania. Indonesia is an archipelago comprising approximately 13,000 islands. It has 33 provinces with over 238 million people, and is the world's fourth most populous country. Indonesia is a republic, with an...

, Taiwan
Taiwan
Taiwan , also known, especially in the past, as Formosa , is the largest island of the same-named island group of East Asia in the western Pacific Ocean and located off the southeastern coast of mainland China. The island forms over 99% of the current territory of the Republic of China following...

 and into the Pacific. Traditional milkfish aquaculture relied upon restocking pond
Pond
A pond is a body of standing water, either natural or man-made, that is usually smaller than a lake. A wide variety of man-made bodies of water are classified as ponds, including water gardens, water features and koi ponds; all designed for aesthetic ornamentation as landscape or architectural...

s by collecting wild fry. This led to a wide range of variability in quality and quantity between seasons and regions. In the late seventies, farmers first successfully spawned breeding fish. However, they were hard to obtain and produced unreliable egg viability. In 1980 the first spontaneously spawning happened in sea cages. These eggs were found to be sufficient to generate a constant supply for farms.

Farming methods

Fry are raised in either sea cages, large saline
Saline water
Saline water is a general term for water that contains a significant concentration of dissolved salts . The concentration is usually expressed in parts per million of salt....

 ponds (Philippines) or concrete tanks (Indonesia, Taiwan). Milkfish reach sexual maturity at 1.5 kilograms (3.3 lb), which takes 5 years in floating sea cages, but 8-10 years in ponds and tanks. Once 6 kilograms (13.2 lb) is reached (8 years) an average of 3-4 million eggs
Egg (biology)
An egg is an organic vessel in which an embryo first begins to develop. In most birds, reptiles, insects, molluscs, fish, and monotremes, an egg is the zygote, resulting from fertilization of the ovum, which is expelled from the body and permitted to develop outside the body until the developing...

 will be produced each breeding cycle. This is mainly done using natural environmental cues. However, there have been attempts using gonadotropin-releasing hormone analogue (GnRH-A) to induce spawning. Some still use the traditional wild stock method. This involves capturing wild fry using nets.

Milkfish hatcheries, like most hatcheries, contain a variety of cultures, as well as the target species. For example rotifer
Rotifer
The rotifers make up a phylum of microscopic and near-microscopic pseudocoelomate animals. They were first described by Rev. John Harris in 1696, and other forms were described by Anton van Leeuwenhoek in 1703...

s, green algae
Green algae
The green algae are the large group of algae from which the embryophytes emerged. As such, they form a paraphyletic group, although the group including both green algae and embryophytes is monophyletic...

 and brine shrimp
Brine shrimp
Artemia is a genus of aquatic crustaceans known as brine shrimp. Artemia, the only genus in the family Artemiidae, has changed little externally since the Triassic period...

. They can either be intensive or semi-intensive. Semi-intensive methods are more profitable with it costing $6.67 US per 1000 fry in 1998, compared with $27.40 per 1000 fry for intensive methods. However, the experience required by labour for semi-intensive hatcheries is higher than intensive.

Milkfish nurseries in Taiwan are highly commercial and have densities of about 2000/litre. Indonesia achieves similar densities but has more backyard-type nurseries. The Philippines have integrated nurseries with grow-out facilities and have densities of about 1000/litre.

There are three methods of outgrowing: pond culture, pen culture and cage culture.
  • Shallow ponds are found mainly in Indonesia and the Philippines. These are shallow 30–40 cm (11.8–15.7 ), brackish ponds with benthic algae, usually used as feed. They are usually excavated from ‘nipa’ or mangrove
    Mangrove
    Mangroves are various kinds of trees up to medium height and shrubs that grow in saline coastal sediment habitats in the tropics and subtropics – mainly between latitudes N and S...

     areas and produce ~ 800kg/ha/yr. Deep ponds (2-3m) have a more stable environment and began in 1970. They so far have shown less susceptibility to disease than shallow ponds.
  • In 1979 pen culture was introduced in Laguna Lake, which had high primary production. This provided an excellent food source. Once this ran out, fertilizer was applied. They are susceptible to disease.
  • Cages culture occurs in coastal bays. These consist of large cages suspended in open water. These rely largely upon natural sources of food.


Most food supply is natural food (known as ‘lab-lab’) or a combination of phytoplankton
Phytoplankton
Phytoplankton are the autotrophic component of the plankton community. The name comes from the Greek words φυτόν , meaning "plant", and πλαγκτός , meaning "wanderer" or "drifter". Most phytoplankton are too small to be individually seen with the unaided eye...

 and macroalgae. Traditionally this was made on site; food is now made commercially to order.

Harvest occurs when the individuals are between 20-40cm (250-500g). Partial harvests remove uniform sized individuals with seine nets or gill nets. Total harvest removes all individuals and leads to a variety of sizes. Forced harvest happens when there is an environmental problem, such as depleted oxygen due to algal blooms and all stock is removed.

Possible parasites include parasitic nematode
Nematode
The nematodes or roundworms are the most diverse phylum of pseudocoelomates, and one of the most diverse of all animals. Nematode species are very difficult to distinguish; over 28,000 have been described, of which over 16,000 are parasitic. It has been estimated that the total number of nematode...

s, copepod
Copepod
Copepods are a group of small crustaceans found in the sea and nearly every freshwater habitat. Some species are planktonic , some are benthic , and some continental species may live in limno-terrestrial habitats and other wet terrestrial places, such as swamps, under leaf fall in wet forests,...

s, protozoa
Protozoa
Protozoa are a diverse group of single-cells eukaryotic organisms, many of which are motile. Throughout history, protozoa have been defined as single-cell protists with animal-like behavior, e.g., movement...

 and helminths. Many of these are treatable with chemicals and antibiotics.

Processing and marketing

Milkfish processing takes two forms. Traditional ways include smoking, drying and fermenting. Bottling, canning and freezing are of recent origin.
There has been a steady increase in demand since 1950. In 2005, 595,000 tonnes was harvested worth USD $616 million.

There is an increasing trend toward value-added products. In recent years the possibility of using milkfish juveniles as bait for tuna
Tuna
Tuna is a salt water fish from the family Scombridae, mostly in the genus Thunnus. Tuna are fast swimmers, and some species are capable of speeds of . Unlike most fish, which have white flesh, the muscle tissue of tuna ranges from pink to dark red. The red coloration derives from myoglobin, an...

long lining has started to be investigated, opening up new markets for fry hatcheries.

External links

The source of this article is wikipedia, the free encyclopedia.  The text of this article is licensed under the GFDL.
 
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