Mediterranean Sharks, Rays Facing Oblivion, Study Says
for National Geographic News
|November 16, 2007|
The great white shark is among 30 species of sharks and rays fast swimming toward oblivion in the Mediterranean Sea, a new report warns.
The newly published World Conservation Union (IUCN) report identifies the waters between Europe and Africa as having the highest percentage of threatened sharks and rays in the world.
Some 42 percent of Mediterranean species are at risk, says the IUCN Red List assessment, performed by the conservation body's Shark Specialist Group.
The group blames the plummeting populations on habitat degradation, sport angling, human disturbance, and overfishing—including fish caught as unintended bycatch. (Related: 8 Million Sharks Killed Accidentally off Africa Yearly [April 17, 2007].)
"Our analyses reveal the Mediterranean Sea as one of the world's most dangerous places on Earth for sharks and rays," Claudine Gibson, IUCN Shark Specialist Group program officer and co-author of the report, said in a statement.
"Bottom-dwelling species appear to be at greatest risk in this region, due mainly to intense fishing of the seabed."
A total of 71 species were assessed. Of the 30 species deemed threatened with extinction, 13 were classified as critically endangered, 8 as endangered, and 9 as vulnerable.
Only ten species (14 percent) were considered free of any extinction risk.
Critically endangered species include the seabed-hugging Maltese skate (Leucoraja melitensis), which lives only in the Mediterranean. Bottom-trawl fishing is the main cause of recent population declines of 80 percent, the IUCN report says.
The shortfin mako shark (Isurus oxyrinchus) and porbeagle shark (Lamna nasus), both prized for their meat and fins, were likewise found to be critically endangered.
"We are particularly concerned about the porbeagle and mako sharks," said shark expert Alen Soldo of the University of Split, Croatia, who participated in the study. "Our studies reveal persistent fishing pressure well in excess of the reproductive capacity of the species."
Endangered species include the giant devil ray (Mobula mobular), which is confined mainly to the Mediterranean.
Its large size and low reproduction rate—females can grow to 17 feet (5 meters) and give birth to only one pup per pregnancy—make the ray especially vulnerable to fishing pressure, the new report warns.
Great White Threat
The great white shark (Carcharodon carcharias) was also assessed as endangered in the Mediterranean, an increased threat category than its current global conservation status of vulnerable.
The study found evidence of a 50 to 60 percent drop in great white numbers in the Mediterranean region.
Overfishing and declines in important prey species such as bluefin tuna have likely contributed to the population collapse, the report says. Habitat degradation due to tourism and development in coastal areas overlapping the shark's habitat are also highlighted in the report.
The IUCN decision to raise the great white's conservation status "is absolutely the correct one," said Richard Pierce, director of the Shark Trust, a marine conservation nonprofit based in Plymouth, England.
Pierce was part of a team that in 2005 spent three months searching for great white sharks in the Adriatic Sea, a former Mediterranean stronghold of the species.
"We chummed [put out shark bait] around the clock at all depths, but we didn't see a sign of a great white," Pierce said. "In fact, we saw very little evidence of sharks in general. It was both terrifying and depressing."
While great white sightings were fairly regular in the Mediterranean during the second half of the last century, "they've have all but ceased completely in the last few years," he added.
Saving the Sharks
The key to conserving remaining shark populations is sustainable fisheries management—something Mediterranean countries have historically struggled to implement, Pierce added.
There are currently no catch limits for commercially fished shark and ray species in the sea, the IUCN Shark Specialist Group says. In addition, only a few species receive any protection as a result of conservation agreements.
A recent deepwater fishing ban below 1,000 meters (3,280 feet) and prohibitions on driftnets and shark finning—slicing off a shark's valuable fins and dumping the body at sea—should help conservation efforts, the group says.
But better enforcement measures are needed if threatened populations are to have the chance to recover, IUCN adds.
Free Email News Updates
Sign up for our Inside National Geographic newsletter. Every two weeks we'll send you our top stories and pictures (see sample).
|© 1996-2008 National Geographic Society. All rights reserved.|