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Authorities in Liuzhou, south- west China’s Guangxi Zhuang Autonomous Region, launched a raid for a cold-blooded menace currently at large in a local river early last month. The target of their hunt was not a serial killer, but the Amazon piranha. The carnivorous fish was responsible for attacks on two residents and considered to be still present near the city.
On July 7, Zhang Kaibo was attacked by at least three red-belly piranhas while giving his pet dog a bath in local Liujiang River. Part of Zhang’s palm was bitten off by the fish.
“I felt the pain and tried to get rid of the fish, but one clung on my palm until I hit it off on a rock,” Zhang said at his home. The fish, chopped into pieces but with its jaw wide open, was on a table in the kitchen.
Zhang’s friend Wu Rihua, the other victim, was bitten on the thumb as he played with the fish in a net by the riverside.
Zhang said that he and his friend killed just one of the three fish that attacked them while the other two swam away.
The fish was later confirmed by experts as a piranha native to South America. Pictures of the fish and Zhang’s injured palm caused an immediate stir online and prompted the local government to take emergency countermeasures. To mobilize local residents to go fishing for the dangerous fish, the city’s fishery authorities offer 1,000 yuan ($157) as a reward for every confirmed piranha kill.
Liuzhou’s game fishing association has also urged its members to join the fish hunt in order to “annihilate the man-eating fish in the shortest possible time.”
Fishery authorities hired five fishing boats and 10 experienced fishermen to catch piranha, but no fish were found during a five-day hunt that concluded on July 13.
“This means the number of piranha is likely rather small,” said Liu Haijun, deputy head of Liuzhou’s fishery supervision agency.“It is like looking for a needle in a haystack.”
Investigators said that piranhas were probably released into the river by residents who bought them as ornamental fish. Guangxi’s tropical climate is similar to the piranha’s natural habitat.
“Piranha can reproduce very fast in environments similar to Amazon River. In addition, the piranhas have no natural enemies here to keep their numbers in check,” said Chen Qingchao, a senior researcher at the South China Sea Institute of Oceanology in Guangzhou, southern Guangdong Province. He warned of the possibility of a large number of native fish falling prey to the alien species.
The piranha is among the most dangerous species in the Amazon region and they often attack people and animals, said Zhou Jie, an expert at the Guangxi Regional Fisheries Research Institute.
As early as 2002, after finding the invasion of the carnivorous fish and worrying about the threat to indigenous fish, China’s fishery authorities launched a campaign to rid the country of all captive piranhas, even those kept by aquariums.
However, even amid public fears of piranha attacks, some pet stores in Liuzhou are still “secretly” selling piranhas to buyers who are willing to wait for a short period of time, according to Xinhua News Agency.
Some experts said that there is no need for the public to panic over the chances of being bitten by piranha as the imported predator is unlikely to thrive locally. “As piranha can only live in warm waters, the relatively harsh winter in Liuzhou makes it almost impossible to maintain a population here,” said Wei Yongwen, head of the city’s Fishery and Animal Husbandry Bureau.
A country besieged
The piranha is not the only alien species that has appeared in China. Although it remains unnecessary for swimmers in Liuzhou to worry about piranha attacks, other alien species have long plagued economies and ecosystems.
According to China’s Fourth National Report on the Implementation of the Convention on Biological Diversity released in 2008, more than half of the 100 of invasive alien species listed by the International Union for the Conservation of Nature had entered China and more than 400 invasive alien species had been recorded in the country, causing annual economic losses totaling around 120 billion yuan ($19 billion).
Usually, these species are introduced to new ecosystems inadvertently, although many are purposefully introduced for food cultivation or for attempts at ecological intervention.
Some of these species reproduce and flourish in their new environment. This success is due largely to the absence of natural predators and parasites, and this may allow alien species to out-compete native species, usurping their niche in the habitat. Introduced species that have negative effects on native species, or cause economic or environmental problems are generally referred to as “invasive” species.
Pomacea canaliculata, the South American freshwater apple snail, was introduced in China as a food in the early 1980s and snail farms were established around the country. However, its taste was not widely accepted by Chinese and farmers started to dump the snails in the wild. The random disposal of the snail, which lays up to 1,200 eggs per month, led to extensive damage to rice fields. The snail lays eggs above the water’s surface, protecting them from small fish and water bugs. To reduce the damage, Chinese farmers are forced to use pesticide to kill the invasive snail, polluting the environment and wiping out many benign organisms.
Introduction of alien species may also lead to genetic pollution. An example is Taiwan island thrush, whose genetic purity is endangered, as the rare thrush interbreeds with its counterparts from the Chinese mainland.
Chen warned that the threat to China’s ecosystems posed by the introduction of alien species, such as bullfrog, red-eared slider and crayfish, is yet to be fully understood. For example, bullfrogs, widely raised in China as food, are also swallowing up different species of smaller indigenous frogs.
China also has many flora examples of ecological disasters caused by alien species. Common cordgrass was first introduced to China from Britain in the 1960s for coastal erosion control purposes. Its dense root systems bind coastal mud and the stems increase silt deposition, thereby assisting in land reclamation from the sea.
The grass was widely planted at coastal sites throughout China in the 1980s. Its invasive nature has surfaced in recent years. As vegetative spread by rhizomes is rapid, the grass colonized large areas of tidal mudflats. Using the oxygen in the seawater when submerged during high tides, the grass has severely smothered local aquatic ecosystems, and has wiped out indigenous clams, shrimp and crabs in the Yellow River Delta less than a decade after it was introduced to this area. China now has the largest total area of common cordgrass in the world, which appeared on the country’s first list of invasive alien species in 2005.
A GREEN DISASTER: Overgrown water hyacinth, an invasive plant introduced in China as pig feed, floats down the Minjiang River in southeastern Fujian Province and clogs up the intake gates of a hydropower plant at the lower reaches
Long-lasting battle
According to Nanfang Daily published in Guangzhou, introduced species posing the greatest threat to agriculture such as the pine wood nematode, water hyacinth, climbing hempweed, vegetable leafminer and rice water weevil, caused direct economic losses totaling more than 50 billion yuan ($7.83 billion) every year in China. The government invests around 1.48 billion yuan ($232 million) annually on preventing new invasive species from entering and spreading.
China’s Ministry of Agriculture established the Center of Management of Invasive Alien Species in 2003. Chen said that this organization has not been able to check the further spread of alien species into China. “An alien species finds its way into China through various pathways, making the preventive work highly difficult. It requires coordination of different government departments,” Chen told Nanfang Daily.
The coconut leaf beetle is a pest that feeds on the young leaves of coconut palms. The in- sect, which is considered native to Indonesia and Papua New Guinea, has recently developed into a serious threat to the coconut industry in south China’s Hainan Province. Resorting to biological control agents, the local government has invested 1.7 million yuan($266,295) to purchase 275 million parasitic wasps in 2012. Another 125 million parasitic wasps are planned to be released into the wild by the end of this year.
Although the use of parasitic wasps has proven effective in reducing the beetles, the wasps could die or stop reproducing after a prolonged period of rain or low temperatures. This explains the surge of beetles each January, the coldest month in Hainan.
“A lot of resources need to be pooled into the research and control of invasive species in China,” Chen said.
On July 7, Zhang Kaibo was attacked by at least three red-belly piranhas while giving his pet dog a bath in local Liujiang River. Part of Zhang’s palm was bitten off by the fish.
“I felt the pain and tried to get rid of the fish, but one clung on my palm until I hit it off on a rock,” Zhang said at his home. The fish, chopped into pieces but with its jaw wide open, was on a table in the kitchen.
Zhang’s friend Wu Rihua, the other victim, was bitten on the thumb as he played with the fish in a net by the riverside.
Zhang said that he and his friend killed just one of the three fish that attacked them while the other two swam away.
The fish was later confirmed by experts as a piranha native to South America. Pictures of the fish and Zhang’s injured palm caused an immediate stir online and prompted the local government to take emergency countermeasures. To mobilize local residents to go fishing for the dangerous fish, the city’s fishery authorities offer 1,000 yuan ($157) as a reward for every confirmed piranha kill.
Liuzhou’s game fishing association has also urged its members to join the fish hunt in order to “annihilate the man-eating fish in the shortest possible time.”
Fishery authorities hired five fishing boats and 10 experienced fishermen to catch piranha, but no fish were found during a five-day hunt that concluded on July 13.
“This means the number of piranha is likely rather small,” said Liu Haijun, deputy head of Liuzhou’s fishery supervision agency.“It is like looking for a needle in a haystack.”
Investigators said that piranhas were probably released into the river by residents who bought them as ornamental fish. Guangxi’s tropical climate is similar to the piranha’s natural habitat.
“Piranha can reproduce very fast in environments similar to Amazon River. In addition, the piranhas have no natural enemies here to keep their numbers in check,” said Chen Qingchao, a senior researcher at the South China Sea Institute of Oceanology in Guangzhou, southern Guangdong Province. He warned of the possibility of a large number of native fish falling prey to the alien species.
The piranha is among the most dangerous species in the Amazon region and they often attack people and animals, said Zhou Jie, an expert at the Guangxi Regional Fisheries Research Institute.
As early as 2002, after finding the invasion of the carnivorous fish and worrying about the threat to indigenous fish, China’s fishery authorities launched a campaign to rid the country of all captive piranhas, even those kept by aquariums.
However, even amid public fears of piranha attacks, some pet stores in Liuzhou are still “secretly” selling piranhas to buyers who are willing to wait for a short period of time, according to Xinhua News Agency.
Some experts said that there is no need for the public to panic over the chances of being bitten by piranha as the imported predator is unlikely to thrive locally. “As piranha can only live in warm waters, the relatively harsh winter in Liuzhou makes it almost impossible to maintain a population here,” said Wei Yongwen, head of the city’s Fishery and Animal Husbandry Bureau.
A country besieged
The piranha is not the only alien species that has appeared in China. Although it remains unnecessary for swimmers in Liuzhou to worry about piranha attacks, other alien species have long plagued economies and ecosystems.
According to China’s Fourth National Report on the Implementation of the Convention on Biological Diversity released in 2008, more than half of the 100 of invasive alien species listed by the International Union for the Conservation of Nature had entered China and more than 400 invasive alien species had been recorded in the country, causing annual economic losses totaling around 120 billion yuan ($19 billion).
Usually, these species are introduced to new ecosystems inadvertently, although many are purposefully introduced for food cultivation or for attempts at ecological intervention.
Some of these species reproduce and flourish in their new environment. This success is due largely to the absence of natural predators and parasites, and this may allow alien species to out-compete native species, usurping their niche in the habitat. Introduced species that have negative effects on native species, or cause economic or environmental problems are generally referred to as “invasive” species.
Pomacea canaliculata, the South American freshwater apple snail, was introduced in China as a food in the early 1980s and snail farms were established around the country. However, its taste was not widely accepted by Chinese and farmers started to dump the snails in the wild. The random disposal of the snail, which lays up to 1,200 eggs per month, led to extensive damage to rice fields. The snail lays eggs above the water’s surface, protecting them from small fish and water bugs. To reduce the damage, Chinese farmers are forced to use pesticide to kill the invasive snail, polluting the environment and wiping out many benign organisms.
Introduction of alien species may also lead to genetic pollution. An example is Taiwan island thrush, whose genetic purity is endangered, as the rare thrush interbreeds with its counterparts from the Chinese mainland.
Chen warned that the threat to China’s ecosystems posed by the introduction of alien species, such as bullfrog, red-eared slider and crayfish, is yet to be fully understood. For example, bullfrogs, widely raised in China as food, are also swallowing up different species of smaller indigenous frogs.
China also has many flora examples of ecological disasters caused by alien species. Common cordgrass was first introduced to China from Britain in the 1960s for coastal erosion control purposes. Its dense root systems bind coastal mud and the stems increase silt deposition, thereby assisting in land reclamation from the sea.
The grass was widely planted at coastal sites throughout China in the 1980s. Its invasive nature has surfaced in recent years. As vegetative spread by rhizomes is rapid, the grass colonized large areas of tidal mudflats. Using the oxygen in the seawater when submerged during high tides, the grass has severely smothered local aquatic ecosystems, and has wiped out indigenous clams, shrimp and crabs in the Yellow River Delta less than a decade after it was introduced to this area. China now has the largest total area of common cordgrass in the world, which appeared on the country’s first list of invasive alien species in 2005.
A GREEN DISASTER: Overgrown water hyacinth, an invasive plant introduced in China as pig feed, floats down the Minjiang River in southeastern Fujian Province and clogs up the intake gates of a hydropower plant at the lower reaches
Long-lasting battle
According to Nanfang Daily published in Guangzhou, introduced species posing the greatest threat to agriculture such as the pine wood nematode, water hyacinth, climbing hempweed, vegetable leafminer and rice water weevil, caused direct economic losses totaling more than 50 billion yuan ($7.83 billion) every year in China. The government invests around 1.48 billion yuan ($232 million) annually on preventing new invasive species from entering and spreading.
China’s Ministry of Agriculture established the Center of Management of Invasive Alien Species in 2003. Chen said that this organization has not been able to check the further spread of alien species into China. “An alien species finds its way into China through various pathways, making the preventive work highly difficult. It requires coordination of different government departments,” Chen told Nanfang Daily.
The coconut leaf beetle is a pest that feeds on the young leaves of coconut palms. The in- sect, which is considered native to Indonesia and Papua New Guinea, has recently developed into a serious threat to the coconut industry in south China’s Hainan Province. Resorting to biological control agents, the local government has invested 1.7 million yuan($266,295) to purchase 275 million parasitic wasps in 2012. Another 125 million parasitic wasps are planned to be released into the wild by the end of this year.
Although the use of parasitic wasps has proven effective in reducing the beetles, the wasps could die or stop reproducing after a prolonged period of rain or low temperatures. This explains the surge of beetles each January, the coldest month in Hainan.
“A lot of resources need to be pooled into the research and control of invasive species in China,” Chen said.