Tilapia as exotic species
Encyclopedia
A number of tilapiine cichlid
s that are native to Africa and the Levant
have been widely introduced into tropical fresh and brackish waters around the world. In some cases, the introductions were deliberate, for example to control invasive aquatic plants, as in the U.S. state
s of Florida
and Texas
. Across much of Asia and Africa they have been introduced into ponds and waterways for the purposes of aquaculture. In other cases, unwanted fish have been released by aquarists or ornamental fish farmers into the wild.
Because tilapiine cichlids are generally large, fast growing, breed rapidly, and tolerate a wide variety of water conditions (even marine conditions), once introduced into a habitat they generally establish themselves very quickly. In doing so they compete with native fish fauna, create turbidity
in the water (by digging) thus reducing the light available for aquatic plants, and eating certain types of aquatic plants causing changes in local aquatic flora. Such problems have been observed in many different places, including Australia, Philippines, and the United States.
, Oreochromis mossambicus
was introduced from Java by the Japanese during World War II, hence its local names, Japanese fish and Java fish. It was formerly very abundant in fresh and brackish waters and in the sea off the north coast. However, since the late 1980s, feral tilapiine cichlid populations in most locations have crashed, possibly due to cross breeding with more recently introduced tilapiine cichlid hybrids (red tilapia O. mossambicus x O. niloticus, possibly also O. honorum and O. aureus). The offspring of the crosses may be strongly sex skewed in favor of males, and inter-species crosses tend to produce fewer fry per brood than single species spawns, thus causing the population to decline, and hybrids with O. niloticus may inherit the lower salinity tolerance of that species, thus restricting the habitats where these tilapiine cichlids are round.
in Southern California
is home to a large population of Oreochromis mossambicus known locally as Salton Sea tilapia. How they got into the Salton Sea is not known for certain. The Salton Sea tilapia feed on plant material, phytoplankton
(particularly diatoms), copepods, rotifers, barnacle
larva
e, and small annelid
worms. One peculiarity of the Salton Sea are the periodic algal bloom
s that cause the fish, including the Salton Sea tilapia, to die in massive numbers, causing a particularly nasty smell.
There are also populations of tilapia in several lakes in Texas; one in Fairfield lake, another in Martin Creek lake, as well as in Lake Conroe and Stubblefield Lake.
in the 1970s aquarium trade, tilapia were introduced into the warm waters of North Queensland
dams for weed and mosquito control. Later genetic studies indicated that at least two separate introductions to the native creeks and rivers occurred. As early as 1979, there were established populations of Tilapia mariae and Cichlasoma nigrofasciatum in the cooler climate of Victoria
, in a pond warmed by a power station . In 1981 they were also noted to be present in the waters of Carnarvon, Western Australia
.
Ten years later it was noted that there were established feral
populations of tilapia throughout the waters of Queensland and Western Australia, and their geographical range was continuing to increase . By 1991 the waters surrounding the Queensland
cities of Brisbane, Townsville, and the Gascoyne River in Western Australia were filled with Oreochromis mossambicus. It was also found that Tilapia mariae was a much less commonly found exotic, though its trapping in rivers north of Cairns indicated that at the time it was possibly extending its range into its preferred water temperature ranges, and that it had a great capacity for tolerating a wide range of salinity levels.
Tilapia are listed as a noxious pest in Queensland
, Australia, and are spreading rapidly into previously untouched and relatively pristine river systems such as the Endeavour River
near Cooktown and the Eureka Creek, a tributary to the Walsh, which runs into the Mitchell.http://www.bigpond.com/news/technology/content/20081010/2387281.asp
As tilapia can thrive in fresh, brackish and salt water, it is thought that infestation in one river can lead to infestation of neighbouring rivers by the fish swimming from the mouth of one to the other through the sea.
Tilapia have been introduced to the mainland of Ecuador, as well as to much of the rest of Latin America, as a fish culture organism.
Tilapiine cichlid
The Tilapiini is a tribe within the family Cichlidae commonly known as tilapiine cichlids. Most of the taxa herein are called "tilapias", a diverse and economically important group containing the genera Oreochromis, Sarotherodon and Tilapia. A number of smaller genera, such as Alcolapia, Danakilia,...
s that are native to Africa and the Levant
Levant
The Levant or ) is the geographic region and culture zone of the "eastern Mediterranean littoral between Anatolia and Egypt" . The Levant includes most of modern Lebanon, Syria, Jordan, Israel, the Palestinian territories, and sometimes parts of Turkey and Iraq, and corresponds roughly to the...
have been widely introduced into tropical fresh and brackish waters around the world. In some cases, the introductions were deliberate, for example to control invasive aquatic plants, as in the U.S. state
U.S. state
A U.S. state is any one of the 50 federated states of the United States of America that share sovereignty with the federal government. Because of this shared sovereignty, an American is a citizen both of the federal entity and of his or her state of domicile. Four states use the official title of...
s of Florida
Florida
Florida is a state in the southeastern United States, located on the nation's Atlantic and Gulf coasts. It is bordered to the west by the Gulf of Mexico, to the north by Alabama and Georgia and to the east by the Atlantic Ocean. With a population of 18,801,310 as measured by the 2010 census, it...
and Texas
Texas
Texas is the second largest U.S. state by both area and population, and the largest state by area in the contiguous United States.The name, based on the Caddo word "Tejas" meaning "friends" or "allies", was applied by the Spanish to the Caddo themselves and to the region of their settlement in...
. Across much of Asia and Africa they have been introduced into ponds and waterways for the purposes of aquaculture. In other cases, unwanted fish have been released by aquarists or ornamental fish farmers into the wild.
Because tilapiine cichlids are generally large, fast growing, breed rapidly, and tolerate a wide variety of water conditions (even marine conditions), once introduced into a habitat they generally establish themselves very quickly. In doing so they compete with native fish fauna, create turbidity
Turbidity
Turbidity is the cloudiness or haziness of a fluid caused by individual particles that are generally invisible to the naked eye, similar to smoke in air. The measurement of turbidity is a key test of water quality....
in the water (by digging) thus reducing the light available for aquatic plants, and eating certain types of aquatic plants causing changes in local aquatic flora. Such problems have been observed in many different places, including Australia, Philippines, and the United States.
Singapore
In SingaporeSingapore
Singapore , officially the Republic of Singapore, is a Southeast Asian city-state off the southern tip of the Malay Peninsula, north of the equator. An island country made up of 63 islands, it is separated from Malaysia by the Straits of Johor to its north and from Indonesia's Riau Islands by the...
, Oreochromis mossambicus
Oreochromis mossambicus
The Mozambique tilapia, Oreochromis mossambicus, is a tilapiine cichlid fish native to southern Africa. It is a popular fish for aquaculture...
was introduced from Java by the Japanese during World War II, hence its local names, Japanese fish and Java fish. It was formerly very abundant in fresh and brackish waters and in the sea off the north coast. However, since the late 1980s, feral tilapiine cichlid populations in most locations have crashed, possibly due to cross breeding with more recently introduced tilapiine cichlid hybrids (red tilapia O. mossambicus x O. niloticus, possibly also O. honorum and O. aureus). The offspring of the crosses may be strongly sex skewed in favor of males, and inter-species crosses tend to produce fewer fry per brood than single species spawns, thus causing the population to decline, and hybrids with O. niloticus may inherit the lower salinity tolerance of that species, thus restricting the habitats where these tilapiine cichlids are round.
United States
Salton SeaSalton Sea
The Salton Sea is a shallow, saline, endorheic rift lake located directly on the San Andreas Fault, predominantly in California's Imperial Valley. The lake occupies the lowest elevations of the Salton Sink in the Colorado Desert of Imperial and Riverside counties in Southern California. Like Death...
in Southern California
Southern California
Southern California is a megaregion, or megapolitan area, in the southern area of the U.S. state of California. Large urban areas include Greater Los Angeles and Greater San Diego. The urban area stretches along the coast from Ventura through the Southland and Inland Empire to San Diego...
is home to a large population of Oreochromis mossambicus known locally as Salton Sea tilapia. How they got into the Salton Sea is not known for certain. The Salton Sea tilapia feed on plant material, 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...
(particularly diatoms), copepods, rotifers, barnacle
Barnacle
A barnacle is a type of arthropod belonging to infraclass Cirripedia in the subphylum Crustacea, and is hence related to crabs and lobsters. Barnacles are exclusively marine, and tend to live in shallow and tidal waters, typically in erosive settings. They are sessile suspension feeders, and have...
larva
Larva
A larva is a distinct juvenile form many animals undergo before metamorphosis into adults. Animals with indirect development such as insects, amphibians, or cnidarians typically have a larval phase of their life cycle...
e, and small annelid
Annelid
The annelids , formally called Annelida , are a large phylum of segmented worms, with over 17,000 modern species including ragworms, earthworms and leeches...
worms. One peculiarity of the Salton Sea are the periodic algal bloom
Algal bloom
An algal bloom is a rapid increase or accumulation in the population of algae in an aquatic system. Algal blooms may occur in freshwater as well as marine environments. Typically, only one or a small number of phytoplankton species are involved, and some blooms may be recognized by discoloration...
s that cause the fish, including the Salton Sea tilapia, to die in massive numbers, causing a particularly nasty smell.
There are also populations of tilapia in several lakes in Texas; one in Fairfield lake, another in Martin Creek lake, as well as in Lake Conroe and Stubblefield Lake.
Australia
Shortly after their first importations to AustraliaAustralia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...
in the 1970s aquarium trade, tilapia were introduced into the warm waters of North Queensland
North Queensland
North Queensland or the Northern Region is the northern part of the state of Queensland in Australia. Queensland is a massive state, larger than most countries, and the tropical northern part of it has been historically remote and undeveloped, resulting in a distinctive regional character and...
dams for weed and mosquito control. Later genetic studies indicated that at least two separate introductions to the native creeks and rivers occurred. As early as 1979, there were established populations of Tilapia mariae and Cichlasoma nigrofasciatum in the cooler climate of Victoria
Victoria (Australia)
Victoria is the second most populous state in Australia. Geographically the smallest mainland state, Victoria is bordered by New South Wales, South Australia, and Tasmania on Boundary Islet to the north, west and south respectively....
, in a pond warmed by a power station . In 1981 they were also noted to be present in the waters of Carnarvon, Western Australia
Western Australia
Western Australia is a state of Australia, occupying the entire western third of the Australian continent. It is bounded by the Indian Ocean to the north and west, the Great Australian Bight and Indian Ocean to the south, the Northern Territory to the north-east and South Australia to the south-east...
.
Ten years later it was noted that there were established feral
Feral
A feral organism is one that has changed from being domesticated to being wild or untamed. In the case of plants it is a movement from cultivated to uncultivated or controlled to volunteer. The introduction of feral animals or plants to their non-native regions, like any introduced species, may...
populations of tilapia throughout the waters of Queensland and Western Australia, and their geographical range was continuing to increase . By 1991 the waters surrounding the Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
cities of Brisbane, Townsville, and the Gascoyne River in Western Australia were filled with Oreochromis mossambicus. It was also found that Tilapia mariae was a much less commonly found exotic, though its trapping in rivers north of Cairns indicated that at the time it was possibly extending its range into its preferred water temperature ranges, and that it had a great capacity for tolerating a wide range of salinity levels.
Noxious pest
Impacts on Australian rivers, creeks and ponds have been great, particularly the dramatic decreases in native fish populations due to predation and competition for food by the fast breeding tilapia that consume a vast range of food sources . Further habitat impacts include increases in local turbidity levels from nesting behaviours. Native fish, invertebrates, and other organisms also experience reduced access to cover through the aggressive territorial defence of breeding and feeding sites by some tilapia species.Tilapia are listed as a noxious pest in Queensland
Queensland
Queensland is a state of Australia, occupying the north-eastern section of the mainland continent. It is bordered by the Northern Territory, South Australia and New South Wales to the west, south-west and south respectively. To the east, Queensland is bordered by the Coral Sea and Pacific Ocean...
, Australia, and are spreading rapidly into previously untouched and relatively pristine river systems such as the Endeavour River
Endeavour River
The Endeavour River on Cape York Peninsula in Far North Queensland, Australia, was named in 1770 by Lt. James Cook, R.N., after he was forced to beach his ship, HM Bark Endeavour, for repairs in the river mouth, after damaging it on Endeavour Reef...
near Cooktown and the Eureka Creek, a tributary to the Walsh, which runs into the Mitchell.http://www.bigpond.com/news/technology/content/20081010/2387281.asp
As tilapia can thrive in fresh, brackish and salt water, it is thought that infestation in one river can lead to infestation of neighbouring rivers by the fish swimming from the mouth of one to the other through the sea.
Galapagos Islands, Ecuador
Tilapia have been introduced to Laguna Junco, an older volcanic caldera. There are no native freshwater fish in the Galapagos, but there are several native invertebrates that spend all or part of their lifecycle in freshwater. At least one, the Galapagos dragonfly, is endemic. Tilapia must be presumed to pose a threat to these invertebrates. The Ecuadorian Park Service is currently (2007) planning an eradication attempt, with the assistance of US Aid for International Development and the US Geological Survey.Tilapia have been introduced to the mainland of Ecuador, as well as to much of the rest of Latin America, as a fish culture organism.
See also
- Invasive speciesInvasive species"Invasive species", or invasive exotics, is a nomenclature term and categorization phrase used for flora and fauna, and for specific restoration-preservation processes in native habitats, with several definitions....
- Tilapiine cichlidTilapiine cichlidThe Tilapiini is a tribe within the family Cichlidae commonly known as tilapiine cichlids. Most of the taxa herein are called "tilapias", a diverse and economically important group containing the genera Oreochromis, Sarotherodon and Tilapia. A number of smaller genera, such as Alcolapia, Danakilia,...
- TilapiaTilapiaTilapia , is the common name for nearly a hundred species of cichlid fish from the tilapiine cichlid tribe. Tilapia inhabit a variety of fresh water habitats, including shallow streams, ponds, rivers and lakes. Historically, they have been of major importance in artisan fishing in Africa and the...
- Tilapia in aquacultureTilapia in aquacultureTilapia has become the third most important fish in aquaculture after carps and salmonids, with production reaching 1,505,804 metric tons in 2002...
- Genus TilapiaTilapia (genus)Tilapia is a large genus of cichlid fishes endemic to Africa, except for a single species that also occurs in the Middle East. The vast majority of the species are from tropical Western and Middle Africa, but there are also a few species in Northern, Eastern and Southern Africa...
- Genus SarotherodonSarotherodonSarotherodon is a genus of tilapiine cichlids, fishes endemic to Africa and the Middle East. A few species from this genus have been introduced far outside their native range, and are important in aquaculture. They mainly inhabit fresh and brackish water, but a few can live in salt water...
- Genus OreochromisOreochromisOreochromis is a large genus of tilapiine cichlids, fishes endemic to Africa and the Middle East. Several species from this genus have been introduced far outside their native range, and are important in aquaculture...
External links
- Tilapia project at Australian Centre for Tropical Freshwater Research, James Cook UniversityJames Cook UniversityJames Cook University is a public university based in Townsville, Queensland, Australia. The university has two Australian campuses, located in Townsville and Cairns respectively, and an international campus in Singapore. JCU is the second oldest university in Queensland—proclaimed in 1970—and the...
http://www.actfr.jcu.edu.au/projects/JCUDEV_015467.html - Information on two tilapia pest species from the Australian Centre for Tropical Freshwater Research as PDF downloads: http://www.actfr.jcu.edu.au/Projects/Pestfish/Profile.htm
- Canonico GC, Arthington A, McCrary JK, and Thieme M (2005): The effects of introduced tilapias on native biodiversity. Aquatic Conservation 15:463-483 http://www.gaianicaragua.org/Canonico%20et%20al%202005%20Aquatic%20Conservation.pdf
- The Flip Side of Tilapia, the Perfect Factory Farm Fish New York Times http://www.nytimes.com/2011/05/02/science/earth/02tilapia.html
- McCrary et al., Tilapia (Teleostei: Cichlidae) status in Nicaraguan naturalwaters http://www.gaianicaragua.org/EBF2007.pdf