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Piranha increase 'due to dams'
Recent outbreaks of piranha attacks on bathers in south-east Brazil may have been caused by the damming of rivers.
By Paul Rincon
BBC News Online science staff
Sunday, 28 December, 2003
Piranha, Sazima

They may only bite once, but piranhas can cause serious injury
They may only bite once, but piranhas can cause serious injury
The link may help to explain other unusual examples of piranha attacks in the country's rivers.
Dams slow the flow of rivers, and may cause an increase in piranha numbers because the fish favour gentle stretches of water for breeding.
Details of the outbreaks appear in the scientific journal Wilderness and Environmental Medicine.
One outbreak occurred in the town of Santa Cruz of Conceicao, whose main river is the Rio Mogi Guacu.
Dammed portions of the stream are popular with tourists and locals who go there to bathe and swim at weekends.
Dormant menace
Piranhas belonging to the species Serrasalmus spilopleura — also known as the speckled piranha — had dwelled in the river and its tributaries in small numbers for many years.
No injuries had previously been recorded with bathers or swimmers, according to the authors of the latest report.
But four years ago, injuries due to piranha bites began to be recorded in the town.
They reached a peak in the late summer of 2002.
Over five weekends in 2002, 38 piranha attacks were recorded.
The rise in attacks has occurred since a dam was built on the river.
Water hyacinth, Sazima

The piranhas spawn in submerged vegetation like water hyacinth
The piranhas spawn in submerged vegetation like water hyacinth
Two more outbreaks were recorded at the towns of Itapui and Iacanga, close to dams on the river Tiete in southeastern Brazil.
Over 50 attacks were recorded in total over two weeks at the sites.
Neither of the towns previously reported a high frequency of injuries from piranhas.
Nest guarding
Professor Ivan Sazima, a zoologist at the Universidade Estadual de Campinas in Sao Paulo, Brazil, told BBC News Online.
"It's a direct consequence of damming.
When you dam a river, you create ideal conditions for the piranha population to rise."
Bathers, Sazima

Bathers often ignore signs like this, which warn of piranhas in the water
Bathers often ignore signs like this, which warn of piranhas in the water
Professor Sazima says damming rivers may cause as much as a ten-fold increase in piranha numbers.
Piranhas lay their larvae in submerged or floating waterweeds such as water hyacinth, which collects in slow-moving rivers.
When rivers flood, much of this vegetation is swept away and this probably controlled piranha populations in the past.
The vegetation offers protection for these nests of piranha larvae, and parents often "brood" over, or guard, them.
"Single bites are caused mainly by the people walking and wading in the waters nearby a piranha nest," says Professor Sazima.
Feeding frenzy
The fish usually bite their victims once, ripping a chunk out of the person and leaving a round, crater-shaped wound with accompanying loss of tissue and bleeding.
Juvenile piranha, Sazima

The roots of water hyacinth offer protection for juvenile piranhas.
The roots of water hyacinth offer protection for juvenile piranhas
One of the people bitten during the outbreak at Santa Cruz of Conceicao had to have their toe amputated.
But there are even worse tales of aggression by the fish.
Over the years, numerous stories of people being attacked and eaten by ferocious schools of piranhas have surfaced.
The authors of this paper claim there is little scientific evidence to support such behaviour.
They say at least three of the people supposedly killed by schools of piranhas actually died from heart failure or drowning and were only feasted on by the creatures after they expired.
The damming of rivers is becoming increasingly common in south-east Brazil due to a greater need for flood protection in this heavily populated region of the country.
MMIII
By Paul Rincon
BBC News Online science staff
Tuesday, 23 July, 2002
US acts over predatory fish
Snakehead - US acts over predatory fish.

Snakeheads threaten the ecological balance of the lakes
Snakeheads threaten the ecological balance
The US Government is to tighten rules on importing a species of predatory fish amid fears it could devastate local ecosystems.
Interior Secretary Gale Norton will announce a series of measures after the northern snakehead fish, which is native to Asia, was found in lakes in seven states.
The fish, which can grow up to three feet (one metre) long and 'walk' on land, are believed to have been dumped by a resident in Maryland who imported them to make soup in a Chinese restaurant.
The snakehead eats other fish and pondlife and can survive out of water for up to three days.

If they got into the larger [water] system, they could alter the food chain and displace other species

John Surrick
Maryland Department of Natural Resources.
Risk of escape
Officials are considering ways to destroy the fish, including poisoning the lake in Maryland where at least 80 baby snakeheads have been found.
Draining the lakes runs a risk of letting the fish escape to other nearby lakes and streams.
"If they got into the larger [water] system, they could alter the food chain and displace other species," said John Surrick, from the Maryland Department of Natural Resources.
The fish, which have heads shaped like a snake's, can eat other fish, frogs, birds and even small mammals.
"You're talking about a total rearrangement of the food chain when you introduce a top predator like this," said Walter Courtenay, from the US Geological Survey in Florida.
Scientists at a Maryland lake containing snakeheads

Scientists are considering poisoning the fish
Scientists at a Maryland lake containing snakeheads
Scientists are considering poisoning the fish
Culinary delight
The interior secretary will propose adding 28 species of snakehead fish to a list of imports which require a special permit.
The measure would make it illegal to trade the fish across state lines.
Snakehead fish
Up to three feet (one metre) long
Able to "walk" on land
Devour pondlife and small mammals
Can survive three days out of water
Snakehead fish are brought into the US for culinary use, and can be eaten smoked or dried.
They are an Asian delicacy, and, with their ugly wide mouths and heavy scales, people in some parts of Thailand and Burma believe the snakeheads to be reincarnated sinners.
Piranha. Photo courtesy of Kenton Phillips.

One zoo has 300 of the predatory fish
One zoo has 300 of the predatory fish
China orders piranhas destroyed
Tuesday, 24 December, 2002
Francis Markus
BBC Shanghai correspondent
Ecologists in China have been expressing concern at the arrival of a new predator, the piranha fish, which has started to appear on sale in pet markets.
Piranhas
There are 17 species of the freshwater fish, varying in size, colouringand ferocity — though all share the same razor-sharp bite
In Tupi Indian language "pira" means fish and "ranha" tooth
Piranha soup — thought to be an aphrodisiac — is an Amazonian delicacy
Piranhas keep river waters fresh and prevent disease by eating animal carcasses
They say if it enters the country's rivers and lakes it could have an unforeseeable effect on the country's aquatic environment.
The authorities in Beijing have ordered piranha fish at aquaria and amusement parks in the capital to be destroyed.
The piranha fish may be an unfriendly creature, but the sharp-toothed native of South America has been gaining popularity as a pet in China.
The fish, which can strip the flesh off an unwitting victim within minutes, have been appearing in ocean parks and on sale in pet markets, in various parts of the country.
But their days may now be numbered.
The authorities in Beijing have ordered all piranhas being kept at aquaria and amusement parks in the capital to be destroyed, and have threatened heavy fines against traders who continue to sell them.
In Shanghai so far some traders say they have been banned from restocking with piranhas, but one shop promised fresh stocks by next week.
  The [piranha's] head with its staring malignant eyes, and gaping, cruelly armed jaws, is the embodiment of evil ferocity
Theodore Roosevelt, Through the Brazilian Wilderness (1914)
The measures come amid growing concern over the proliferation of the fish, with reports that they are being bred along northern China's Yellow River and may already have entered its river system, even though some scientists say that the winter temperatures there are too cold for them to survive.
  Piranhas are not the danger to people as portrayed in popular[culture]...
Many piranha species feed principally on seeds or the finsand scales of other fishes
Amazon fish specialist Michael Goulding
Ecologists have been warning that if the fish do find their way into China's rivers and lakes, aquatic life could be seriously jeopardised.
One commentator called for the government to strengthen the laws on importing such foreign species into China.
But it may already be too late to prevent the fish from having an, as yet, unforeseeable impact on China's aquatic environment.
Peaches Red-bellied piranha

eaches: Zoo staff think the piranha was testing her mate
Peaches: Zoo staff think the piranha was testing her mate
Thursday, 1 June, 2000
Hungry piranha seeks good catch
A zoo is appealing for a new mate for a female piranha after the fish devoured her previous one.
Red-bellied piranhas Peaches and Melba had drawn hundreds of visitors to the Anglesey Sea Zoo, in north Wales, and it was hoped they would produce some young.
But the grim discovery was made after staff went to give the pair a morning feed.
The zoo's aquarist, Chris Smith, said: "At first we thought Melba was hiding behind some reeds, but on closer inspection we found Peaches had eaten most of him," said zoo aquarist Chris Smith.
"She had taken huge chunks out of him. They have been together for a few years and did have the occasional fight, but obviously this squabble went too far.
Import restrictions
"Peaches is seven years old and is coming up to a breeding age, so she was probably testing him.
"She is slightly bigger than Melba and he obviously didn't come up to scratch."
The zoo in Brynsiencyn, Anglesey, is searching for a replacement in the UK because of import restrictions.
"The problem is you can't import piranha any more so we are looking throughout the country," Mr Smith added.
"We will probably choose a fish that is slightly bigger than Peaches so she won't eat him."
The world's smallest known fish can measure as little as 7.9mm
The world's smallest known fish can measure as little as 7.9mm
Scientists find 'smallest fish'
By Roland Pease
BBC science correspondent
Wednesday, 25 January 2006
Scientists have discovered the smallest known fish on record in the peat swamps of the Indonesian island of Sumatra.
Mature individuals of the Paedocypris genus can be as small as 7.9mm (0.3in) long, researchers write in a journal published by the UK's Royal Society.
But they warn long-term prospects for the fish are poor, because of the rapid destruction of Indonesian peat swamps.
The fish have taken extreme measures to survive in extreme habitats - pools of acid water in a tropical forest swamp.
Food is scarce but the Paedocypris — smaller than other fish by a few tenths of a millimetre - can sustain their small bodies grazing on plankton near the bottom of the water.
small fish against finger
Human threat
To keep their size down, the fish have abandoned many of the attributes of adulthood — a characteristic hinted at in their name.
Their brain, for example, lacks bony protection and the females have room to carry just a handful of eggs.
The males have a little clasp underneath that might help them fertilize eggs individually.
Being so small, the fish can live through even extreme drought, by seeking refuge in the last puddles of the swamp.
But they are now threatened by humans.
Widespread forest destruction, drainage of the peat swamps for palm oil plantations and persistent fires are destroying their habitat.
Science may have discovered Paedocypris just in time - but many of their miniature relatives may already have been wiped out.

        New species of grenadiers found in the western Mediterranean        
        New species uncovered in Venezuela        
        Ocean census discovers new fish       
        Atlantic cod — ninety percent decline        
        Tuna Stocks Close to Exhaustion        
        How we are emptying our seas        
       Ice sheet reveal ancient plant matter      
       High-resolution polar ice and sea ice elevation      
Pygmy Elephants and Palm Oil Threat
The only hope for these elephants now is protection of the lowland forest as nature reserves or sustainably managed logging concessions.
Forests are being burned and peat wetlands drained for plantations, causing huge releases of carbon dioxide into the atmosphere.
Land clearances in Indonesia to meet the growing global demand for palm oil pose a serious threat to the environment.
Gorillas, orangutans, and corals are among the plants and animals which are sliding closer to extinction.
     Clock ticking for Indonesian rainforest       
     Deforestation illegal logging primarily not because of poverty but corruption     
      Destruction of rainforest Indonesia Riau province     
Extreme drought in Amazon rainforest linked to deforestation and climate change
The trouble has been that while traditional aerial images can show areas that have been completely destroyed, they do not reveal selective logging of valuable trees such as mahogany.
Brazilian officials praised the scientists for highlighting the issue of selective logging, but said the new figures were hard to believe.
     Clock ticking for Indonesian rainforest       
     Deforestation across the world     
       Amazon 'stealth' logging revealed    
 
 
 
 
 
For archive purposes, this article is being stored on TheWE.cc website.
The purpose is to advance understandings of environmental, political,
human rights, economic, democracy, scientific, and social justice issues.