"The reason I love the sea I cannot explain - it's physical. When you dive you begin to feel like an angel. It's a liberation of your weight." (Jacques-Yves Cousteau)

quarta-feira, 25 de agosto de 2010

Why the hammerhead shark got its hammer


It's one of evolution's most eccentric creations: a head shaped like a hammer. Now, a study suggests that the hammerhead shark may have evolved its oddly shaped snout to boost the animal's vision and hunting prowess.

For over a century, scientists have speculated why hammerheads evolved such an odd shape and whether having eyes so far apart would enhance their vision. In 1942 a leading authority on sharks, Gordon Walls, suggested the position of the shark's eyes prevented it from having binocular vision. But others have argued exactly the opposite, saying the animals must have enhanced eyesight.

Now, hammerhead sharks have had their first eye examination, and it has laid the debate to rest. Sharks with wider heads have better binocular vision – all the better to track fast-moving prey like squid with far more accuracy than sharks with close-set eyes.

The research also shows that hammerheads – among other sharks – have a 360-degree view of the world in the vertical plane, allowing them to simultaneously see prey above and below them.

Sharks at the optometrist

Michelle McComb of Florida Atlantic University in Boca Raton and colleagues compared the visual fields of three species of hammerhead – the winghead, the bonnethead and the scalloped hammerhead – with those of two other species of shark.

After implanting electrodes into the sharks' eyes, the researchers moved a beam of light across them until the eyes no longer demonstrated electrical activity. This allowed them to measure each eye's field of vision, which they summed to calculate each species' "binocular overlap".

"To our surprise, we found that the degree of overlap increased as the head of the hammerhead species widened," says McComb. The shark with the widest head, the winghead, had 48 degrees of binocular overlap; the others ranged from 10 to 32 degrees.

Eyes on the ball

That overlap helps hammerheads to perceive depth as they hunt, says Demian Chapman of the Institute for Ocean Conservation Science at Stony Brook University in New York. "I've seen hammerheads chasing stingrays in the Bahamas," he says. "The rays are fast and can turn rapidly, so if the hammerhead is to catch one, it has to be able to keep its eye on the ball."

Shark biologist Samuel Gruber of the Bimini Biological Field Station in Miami, Florida, says the paper has changed his view of the debate.

Previously, researchers have theorised that the hammerhead's head may improve its sense of smell, boost its ability to locate prey using electric fields, improve its manoeuvrability or help it to pin down struggling rays so it can bite off their wing-like fins.

Journal reference: The Journal of Experimental Biology, vol 212, p 4010

Source: New Scientist

Hammerhead Shark Killed, Left On Dock


A Palm Beach County conservationist said a 9-foot female scalloped hammerhead shark was caught and left on a dock at Sailfish Marina in Palm Beach Shores.Jim Abernathy sent photos of the shark to WPBF 25 News. Dock attendants told him that the captain of a vessel had brought the shark to the dock and left it.Abernathy said that it's illegal to kill a fish that you don't plan to eat. Abernathy said fish that won't be eaten must be immediately released under Florida law.Abernathy said this shark may have been pregnant."(Hammerhead sharks are) being driven closer and closer to extinction because of commercial fishing to their fins, and also because of careless and wasteful practices like what we've seen today," said Abernathy.

Hammerhead Shark

Shark Week Sensationalism that Sells

Sharks are being given a bad rap again when Discovery Channel ‘Sinks Teeth Into Shark Week 2010’ with a lineup of programs, many of which depict sharks as bloodthirsty man-eaters. We desperately need improved public perception to win the battle against plummeting shark populations, and irresponsible TV and media portrayal of sharks’, which perpetuates poor perceptions of them, only adds to their threat. The media have immense power to help us save our planet’s resources through responsible reporting, or not. They can choose to continue accelerating the demise of these much maligned animals, which will ultimately result in our own downfall as everything in nature is connected; or they can support us and help us save them so we might save ourselves. It is a shame on Discovery Channel to see them continuing to work against the good efforts we as shark conservationists around the globe fight so hard to achieve, changing fear and loathing of sharks to much needed understanding and admiration.

But instead of me continuing to express my utmost disdain and irritation at the shortsighted, ignorant, high ratings, big dollar driven commissioning editors, and the like, at Discovery Channel, I will leave it up to fellow conservationist and multi-award winning filmmaker and author, Chris Palmer. Chris has spent 25 years producing more than 300 hours for prime time television and the giant screen (IMAX) film industry, and if anyone’s opinion should be respected it is his: “Teeth of death,” “Shark feeding frenzy,” “The Worst Shark Attack Ever.” It is that time of year again, when the Discovery Channel brings out shows like these as part of its annual “Shark Week” programming. This week of bloody feeding frenzies and vicious shark attacks is part of a larger trend in nature programming. Instead of seeking to educate or to promote environmental conservation, these shows focus only on presenting graphic, sensationalized animal violence. Programs like those in Shark Week – while they might garner high ratings and attract advertiser dollars – all too often mislead the audience, exploit animals, and fail to promote conservation. It is easy to understand why Shark Week or other shows like “Untamed and Uncut”, “Man vs. Wild”, or “When Animals Attack” would attract viewers…”

Read more: http://www.huffingtonpost.com/chris-palmer/shark-week—-education-o_b_660876.html

terça-feira, 24 de agosto de 2010

Hammerhead Shark


The hammerhead sharks are a group of sharks in the family Sphyrnidae, so named for the unusual and distinctive structure of their heads, which are flattened and laterally extended into a "hammer" shape called a "cephalofoil". Most hammerhead species are placed in the genus Sphyrna; some authorities place the winghead shark in its own genus, Eusphyra. Many, not necessarily mutually exclusive, functions have been proposed for the cephalofoil, including sensory reception, maneuvering, and prey manipulation. Hammerheads are found worldwide in warmer waters along coastlines and continental shelves. Unlike most sharks, hammerheads usually swim in schools. Some of these schools can be found near the Cocos Islands by Costa Rica.


The nine known species range from 0.9 to 6 m (3.0 to 20 ft) long. The average hammerhead shark weighs about 500 pounds, but some may grow up to 1000. All the species have a projection of their face on all sides of the head that gives it a resemblance to a flattened hammer.

It was determined recently that the hammer-like shape of the head evolved to enhance the animal's vision. The positioning of the eyes give the shark good binocular vision, as well as 360-degree vision in the vertical plane, meaning they can see above and below them at all times. The shape of the head was previously thought to help the shark find food, aiding in close-quarters maneuverability and allowing sharp turning movement without losing stability. However, it was found that the unusual structure of its vertebrae allowed it to make the turns correctly, more often than its head. The hammer would also shift and provide lift.

Hammerheads are one of the most negatively buoyant of sharks. Like all sharks, hammerheads have electroreceptory sensory pores called ampullae of Lorenzini. By distributing the receptors over a wider area, hammerheads can sweep for prey more effectively. These sharks have been able to detect an electrical signal of half a billionth of a volt. The hammer also allows the nostrils to be placed farther apart, increasing its ability to detect chemical gradients and localize the source.

Hammerheads have disproportionately small mouths and seem to do a lot of bottom-hunting. They are also known to form schools during the day, sometimes in groups of over 100. In the evening, like other sharks, they become solitary hunters. Hammerheads are notably one of the few animals that acquire a tan from prolonged exposure to sunlight. Tanning occurs when a hammerhead is in shallow waters or close to the surface for long periods.


Source: Wikipedia Shark Portal

Scalloped Hammerhead Shark

Along with the seven other known species of hammerhead sharks, the scalloped hammerhead has a strange, flattened, T-shaped head. In this species, the front of the head has three notches, which produces the scalloped shape from which it takes its name.

The eyes are located at the sides of the head. Hunting near the seabed, the shark swings its head from side to side, looking for prey such as fish, other sharks, octopus, and crustaceans, and using sensory pits on its head to detect the electrical fields of buried prey such as rays. The head may also function as an airfoil, giving the shark lift and helping it to twist and turn as it chases its prey.

Scalloped hammerheads may be seen in large shoals of over a hundred individuals. They give birth to live young in shallow bays and estuaries, where the skin of the young darkens to give protection against sunlight.

Threats

The fins of the scalloped hammerhead are extremely valuable for use in shark fin soup and the scalloped hammerhead is taken both as a target species and as bycatch with pelagic longlines, fixed bottom longlines, nets and pelagic trawls. The meat, skin and oil are also utilized. The scalloped hammerhead has declined by more than 75 percent in the past 15 years along the eastern U.S. and is listed as “Endangered” on the IUCN Red List.

The decline of the scalloped hammerhead, and other great sharks in the Atlantic, has led to an increase in the cownose ray population which resulted in a collapse of the century-old North Carolina bay scallop industry. Oceana’s Predators as Prey report details this cascading effect and other important impacts the loss of sharks will have on the marine ecosystem.

Source: Oceana.org

New week, new shark information

This week I'll be talking about the Hammerhead Shark.
The great and the scalloped hammerhead are listed on the World Conservation Union's (IUCN) 2008 Red List as endangered, whereas the smalleye hammerhead is listed as vulnerable. The status given to these sharks is as a result of over-fishing and demand for their fins, an expensive delicacy. Among others, scientists expressed their concern about the plight of the scalloped hammerhead at the American Association for the Advancement of Science annual meeting in Boston. The young swim mostly in shallow waters along shores all over the world to avoid predators.

What kind of shark are you ?

Take the quiz on the Discovery Channel "Shark Week" website and find out which shark resembles you the most. By the way, i'm a Hammerhead Shark :)
Just follow the link below...

What kind of shark are you ?

quarta-feira, 18 de agosto de 2010

Hong Kongers wage campaign against shark fin


HONG KONG — When Steven Leung and Sylvia Cheung celebrated their nuptials in this southern Chinese financial center recently, they lavished their guests with one sumptuous dish after another — bird nest soup, lobster, abalone.

But one traditional dish was missing from the 13-course Cantonese banquet. The newlyweds chose not to serve shark fin soup.

"I saw the cruelty in shark slaughtering in online videos. The way the fish is dumped back into the water — it is just inhumane," Leung said, referring to the practice of hacking off the fins of sharks, then setting them free.

The Hong Kong couple are part of a growing grass-roots movement in this global hub of shark fin consumption that aims to remove the staple of gourmet Chinese cuisine from restaurant menus.

"Shark fin is not a necessity at banquets, as long as guests are well-treated and there is good food," said Cheung. "We have great substitutes for the soup that are equally as prestigious and exquisite."

For centuries, shark fin — usually served as soup — has been a coveted delicacy in Chinese cooking, extolled for its supposed ability to boost sexual potency, enhance skin quality, increase one's energy (or "qi"), prevent heart diseases and lower cholesterol.

To prepare for soup, dried fin first is soaked in water overnight, then boiled for several hours to soften the cartilage and remove impurities. It then is cooked in a rich chicken broth with salted ham, mushrooms, dried scallops and abalone. Shark fin itself is tasteless, but has a slippery and glutinous texture.

It's an especially cherished menu item in wealthy Hong Kong, a pricey status symbol for its materialistic and status-conscious people. Depending on the quantity and the quality of the fin in the soup, the dish can cost from $10 to $150 a bowl.

"Hong Kong is the Grand Central Station in the shark fin trade," said Canadian filmmaker Rob Stewart, who chronicled the shark-hunting industry in the 2007 documentary "Sharkwater."

Nearly 80 percent of Cantonese-speaking residents in the city of 7 million had consumed shark fin, according to a poll conducted by the conservation group WWF Hong Kong in 2005. The International Union for the Conservation of Nature estimates that the former British colony handles between 50 to 80 percent of the global shark fin trade. Hong Kong was the world's top importer of shark fin in 2007, taking in 10,209 metric tons, or a total value of $276.7 million, according to the latest figures from the United Nations' Food and Agricultural Organization.

However, activists like Stewart are making an impression on a younger generation of Hong Kongers like the Leungs by touting the gruesome toll of the dining habits of their parents and ancestors.

As many as 73 million sharks are killed annually for their fins, according to a 2006 study by fisheries expert Shelley Clarke, a visiting researcher at London's Imperial College. Shark populations have plummeted from overfishing, with nearly a third of open ocean sharks facing extinction, according to the International Union for the Conservation of Nature.

In April, the U.S. state of Hawaii banned the sale and possession of shark fin. The campaign is now gaining ground in Hong Kong.

Computer engineer Clement Lee set up a Facebook group in March urging locals to cut their gift money to newlyweds by 30 percent if they serve shark fin soup at their wedding banquets. The group now as more than 18,000 supporters. In July, he forced Citibank Hong Kong drop a shark fin set dinner discount for its credit card holders after criticizing the marketing campaign in another Facebook group.

And since June, Hong Kong environmental group Green Sense has signed up 182 primary and secondary schools for their "Sharks We Care" campaign, with the schools pledging not to serve shark fin at banquets and activities.

Responding to the new consciousness, local restaurants are starting to offer shark-fin free menus. Chinese restaurant chain L.H. Group said the response has been positive.

"We get a lot of inquiries and people interested in ordering the new menu weekly since we rolled out in May," said company spokeswoman Toby Kwan.

Local shark fin traders also say they are noticing the shift in attitudes.

"Our shark fin business has dropped considerably. Environmental groups are writing such bad stories about shark fin. A lot of people do not want to buy shark fin now," said Mak Ching-po, chairman of the Hong Kong Dried Seafood and Grocery Merchants Association. He declined to give an exact figure.

Still, some outside observers say conservation activists are waging a tough battle against a deeply rooted tradition.

"The consumption perhaps will drop but it cannot be eliminated," Hong Kong Chefs Association chairman Andreas Muller said. "Some restaurants may boycott shark fin, but there are others who will continue. It's a custom — same as eating sausage in Germany."

Lee, the Facebook campaigner, acknowledged that for many Hong Kongers it's more important to demonstrate their generosity than to save sharks.

"Many hosts still believe that it is an insult to the guests — or 'losing face' — to not serve shark fin soup in a formal banquet," he said.

The Hong Kong government has also been lukewarm. Green Sense reached out to 56 government departments in May, urging them to ban shark fin from official functions. Only 14 departments responded, with just one agreeing to the request.

It's also unclear if the newfound awareness in Hong Kong will filter through to booming mainland China, where increasingly affluent residents are fast developing a taste for expensive dining.

"The mainland Chinese market for shark fin is large, and there is an upward trend because mainland Chinese are becoming wealthier. But I believe changing attitudes here can make an impact on consumption across the border," WWF Hong Kong spokeswoman Silvy Pun said.


By JOYCE WOO (AP)

Green Heroes - Rob Stewart

On a mobile phone?

Click the image to watch the video in H.264

video


Rob Stewart is the award-winning director of Sharkwater. His provocative documentary challenges the age-old image of sharks as man-eaters and suggests the real villains may be those who kill 100 million sharks each year.

Did you know that sharks have been swimming in the oceans for 420 million years and survived five major extinctions?

"Ordinary people have always made a difference and changed the world and that's what it's going to be in the future."

Please support the following organizations that Rob Stewart is affiliated with:
Shark Water

Credits:
Sharkwater film clips and marine photography courtesy of Rob Stewart.
Music by Miguel Gauthier

European Shark Week 2010: Focus on Finning


It's time to strengthen the finning ban

9-17 October 2010

Every October, members of the Shark Alliance in Europe run a week of activities for supporters and other shark enthusiasts to find out more about sharks and shark conservation and add their voices to those demanding that policy makers secure the future health of shark populations.

During European Shark Week (ESW) in 2009 over 300 activities were held in 15 European countries and more than 93,000 people signed a petition, handed over to the Spanish authorities in January this year, urging Spain to end its opposition to improving the EU ban on shark finning and lead the EU towards more effective regulation.

More information on last year’s events with pictures and the results of the colouring competition for young supporters is available here.

This year we need to keep the pressure on.

More than three years ago, Members of the European Parliament (MEPs) called on the European Commission to strengthen the EU finning ban which is currently fraught with loopholes and puts sharks at risk. Next year the European Parliament will be asked to vote on a new regulation that the Commission are drafting and will be issuing for consultation soon.

We need to ensure that MEPs, as our elected representatives, continue to press for what they called for more than three years ago and help close the loopholes.

The Shark Alliance will be working with MEPs to ensure their support and this October we want them to hear many other voices as well.

Put the 9th to 17th October in your diaries. Watch this space for more information on plans, ideas, materials and a call to action. If you want to find out more, or better, offer your support - contact Donna Mattfield, donnamattfield@yahoo.com

Source: Shark Alliance

Whale Shark Project

The Shark Trust and Project AWARE is encouraging water users all around the world to submit images of their Whale Shark sightings in order to better understand their behaviour, population and biology. Working with research groups, divers, scientists and holiday makers we are attempting to improve the protection and understanding of the world's largest fish.

How you can help - Snapping a Whale Shark

The pattern of light pigmented spots and coloration of Whale Sharks is unique to each individual. Therefore, when diving with Whale Sharks, these ar
eas should be targeted for the most useful photos. The pigmentation patterns of Whale Sharks differs on each side of the body so it is important to note which side of the shark the photo is from to avoid confusion especially if planning to process the photos as slides.

Photos of the area around the gills, or around the primary dorsal fin are particularly useful.

Specific target areas for photo-id

More info:
Whale Shark Project

Whale Shark (BBC Planet Earth)



Source & Copyright: BBCWORLDWIDE

terça-feira, 17 de agosto de 2010

Shark Attack Victims Fight to Save Sharks


If you can forgive a shark for making you its dinner — you're a good person. If you can forgive it and fight for its protection and survival — you're an angel.

Chuck Anderson, 44, a high school coach and vice principal, tells his dramatic story of being mangled by a shark. In 2000, he was swimming off the Gulf Coast, and he lost his right arm above the elbow. Despite any grudges he may of had against the shark, Anderson joined a group of attack victims on a quest to persuade the US Senate to save the sharks.

Out of love and compassion, nine shark attack survivors trekked to Washington D.C., organized by the Pew Environment Group, to help ban shark finning, a process where fishermen slice off a shark's fin to sell in primarily Asian markets as a soup ingredient. Up to 3 million sharks are killed annually for their fins. The group of activists are still waiting to hear the results of their plea.

Watch Anderson's miraculous tale of survival and even more outstanding attitude towards shark preservation.

By Rachel Rossitto

Source: Tonic.com

Whale Shark - Rhincodon typus



The whale shark is a graceful, slow-moving giant and the largest fish in the world. At 5 ft (1.5 m) wide, its mouth is large enough to fit a human inside, but it is a harmless filter feeder that eats only plankton and small fish.

To obtain the huge amount of food it needs, it sucks water into its mouth and pumps it out over its gills, where particles of food become trapped by bony projections called gill rakers and are later swallowed.

This shark has the thickest skin of any animal, at up to 4 in (10 cm) thick. Prominent ridges run the length of its body, and it has a large, sickle-shaped tail. The pattern of white spots on its back is unique to each fish, enabling scientists, through analysis of photographs, to identify individuals.

While little is known of their ocean travels, satellite tagging has shown that some whale sharks migrate across entire oceans. Whale shark eggs hatch inside the mother, and she gives birth to live young. Whale sharks are killed for their meat and fins (used in soup), although they are legally protected in some countries.

Feasting on plankton

Every year, around April, whale sharks migrate to Ningaloo Reef off northwestern Australia for a plankton feast. The plankton explosion results from a simultaneous mass spawning of the reef’s corals, possibly triggered by the full moon.

Threats

A majority of whale sharks are caught before they even reach maturity. Their fins fetch a high price in Asian markets, although trade is regulated by the Convention on International Trade in Endangered Species of Wild Fauna and Flora (CITES). Overfishing is a serious concern as whale shark populations are decreasing in numerous regions and the average size of Australian whale sharks is shrinking.

  • Order Orectolobiformes
  • Length 40–65 ft (12–20 m)
  • Weight Over 13 tons (12 metric tons)
  • Depth Surface, deep water in winter
  • Distribution Tropical and temperate waters worldwide

Source: Oceana.org

Discovery Channel skateboard deck auction to raise funds for shark conservation

Discovery’s Shark Week ended August 5th—but that doesn’t mean you can’t still get in on some marine predator action. As part of Shark Week’s sponsorship of the X Games, which recently concluded in Los Angeles, Discovery Channel had a signature series of shark-themed skateboard decks created by designer friends and colleagues. Each deck is one-of-a-kind and only available through auction on CharityBuzz, with proceeds benefitting ocean conservation organization Oceana.

According to Oceana, “Today, sharks face a new threat – humans. Each year, commercial fishing kills more than 100 million sharks worldwide – including tens of millions just for their fins. Sharks are especially vulnerable to pressure from human activities because of their slow growth and low reproductive potential. Many shark populations have declined to levels where they are unable to perform their roles as top predators in the ecosystem, causing drastic and possibly irreversible damage to the oceans.”

Source: http://www.thisdishisvegetarian.com

Welcome

Hi, this blog was created to provide information regarding sharks and their conservation. Here you'll be able to find facts and interesting information about most shark species, environmental issues and news, I'll try and post lots of information about a different shark every week.