Subscribe to our free daily newsletters
. Earth Science News .




Subscribe to our free daily newsletters



Oceans Are 70 Percent Shark Free

There won't be any sharks eating this little puppy.
by Staff Writers
Washington DC (SPX) Feb 22, 2006
Marine scientists have discovered that the deepest oceans of the world would appear to be shark free. In a paper published today, an international team of researchers, led by the University of Aberdeen, reveal that sharks have failed to colonise at depths greater than 3,000 metres. Sharks occur throughout the world's oceans. It had been hoped that as man explores deeper into the abyss that new species would be discovered.

However, 20 years of exploration, combined with analysis of records over the past 150 years, has convinced the team of scientists that the world's oceans are 70% shark-free. Their findings are published in Proceedings of The Royal Society, Biological Series.

The average depth of the oceans is 4,000m and bony fishes - relatives of cod - thrive down to around 9,000m depth. Scientists do not know why sharks are absent from the deep but suggest one possible reason could be due to lack of food.

They warn their finding has environmental implications.

Professor Monty Priede, Director of Oceanlab at the University of Aberdeen, said: "Sharks are apparently confined to around 30% of the world's oceans, and all populations are therefore within reach of human fisheries, near the surface and at the edges of deep water, around islands, seamounts and the continents.

"Sharks are already threatened worldwide by the intensity of fishing activity but our finding suggests they may be more vulnerable to over-exploitation than was previously thought."

The scientists based their conclusions on a wide range of data which includes information gathered during a major month long expedition along the Mid-Atlantic Ridge between Iceland and the Azores in 2004.

More than 100 scientists from over 16 countries were involved in the MAR-ECO project which is part of the 10-year Census of Marine Life programme which is exploring the abundance, distribution and diversity of life in the world's oceans.

The team also used findings built up over the last two decades when the University of Aberdeen's Oceanlab started developing landers - remotely operated vehicles - which have been used in deep waters all over the world. Expeditions usinglanders visited the deepest abyssal plain on the planet - North of Hawaii; the South Atlantic off the Falkland Islands; the North West African slopes off Angola, the North East Atlantic Ocean, West of Ireland, and five research cruises in the North East Atlantic.

The scientists say that the deepest confirmed report of a shark is at 3,700m. They believe it is very unlikely that major new populations will be discovered in abyssal regions.

Professor Priede added: "As far as we can see there is no hidden reserve of sharks in the deep sea. All we see, is all there is, it's highly unlikely we are going to find anymore."

The oceanic abyss which is where the ocean is deeper than 3,000 metres - is characterised by absence of solar light, high pressures and remoteness from surface food supply. Deep water sharks have oil-rich livers which keep them buoyant, and a high energy demand, which researchers believe cannot be sustained in the extreme conditions of the abyss where there is a lack of food.

Related Links
Census of Marine Life
University of Aberdeen

Dragonflies Uses Drag To Carry Their Weight Offer Insight Into Flight
St Louis MO (SPX) Feb 22, 2006
If mastering flight is your goal, you can't do better than to emulate a dragonfly. With four wings instead of the standard two and an unusual pitching stroke that allows the bug to hover and even shift into reverse, the slender, elegant insect is a marvel of engineering.







  • Levee Modeling Study To Provide Technical Data For Rebuilding New Orleans
  • Scientists Say California Quake Could Cause Katrina II
  • US Troops Join Landslide Rescue As Buried School Is Located
  • Cornell, WCMC And LockMart To Create Plan To Manage Mass Casualties In Disasters

  • Greenland Glaciers Dumping Ice Into Atlantic At Faster Pace
  • The Arctic And Global Warming
  • Late Pleistocene Americans Faced Chaotic Climate Change Environments
  • Ancient Climate Studies Suggest Earth On Fast Track To Global Warming

  • Earth From Space: Copenhagen, Denmark
  • ALOS Captures First Image of Fujiyama
  • Southern Greenland Glaciers Dumping Ice Faster
  • NASA Satellite Technology Helps Fight Invasive Plant Species

  • Environmental Metagenomics Tapping Opportunities For Clean Energy
  • Walker's World: EU's Bold Caucasus Bid
  • Garbage Truck Industry Ponders Move To LNG
  • Nuclear Fusion On A Tabletop

  • Grants Put ANU In Bird Flu Fight Frontline
  • New Influenza Vaccine Takes Weeks To Mass Produce
  • Bird Flu Hits Western Europe
  • Bird Flue Hits Africa

  • Dragonflies Uses Drag To Carry Their Weight, Offer Insight Into Flight
  • Oceans Are 70 Percent Shark Free
  • Sexual Reproduction Delays Aging In A Mammalian Species
  • Monitoring Baleen Whales With Autonomous Underwater Vehicles

  • Fourfold Increase In British Radiation Levels After Iraq Invasion
  • Water Cut Off For 20,000 People After Latest Chinese River Toxic Spill
  • China To Step Up Environmental Protection Efforts
  • Disturbing Former Farmlands Can Rouse Old Pesticides

  • Melting Yukon Ice Fields Reveal Ancient Canadian Footwear
  • Love That Baby Fat
  • Early Human Ancestors Walked On The Wild Side
  • East Africa's Rapid Development Presents Complex Push And Pull

  • The content herein, unless otherwise known to be public domain, are Copyright 1995-2006 - SpaceDaily.AFP and UPI Wire Stories are copyright Agence France-Presse and United Press International. ESA PortalReports are copyright European Space Agency. All NASA sourced material is public domain. Additionalcopyrights may apply in whole or part to other bona fide parties. Advertising does not imply endorsement,agreement or approval of any opinions, statements or information provided by SpaceDaily on any Web page published or hosted by SpaceDaily. Privacy Statement