Richard Black, BBC News 10 Jun 08;
Sharks in the Mediterranean Sea have undergone a massive decline over the last two centuries, scientists have discovered from historical records.
Some species shrunk by more than 99% over the period, mainly due to fishing.
Researchers used fishermens' notes and archive records to plot population trends of five top predatory sharks.
The study, in the journal Conservation Biology, comes just weeks after a warning that half of the world's ocean-going sharks face extinction.
Sharks and their close relatives, the rays, are particularly vulnerable to over-fishing as they grow and reproduce slowly.
"There is a long history of fishing in the Mediterranean, especially coastal fishing," said study leader Francesco Ferretti from Dalhousie University in Halifax, Canada, who has been working in the Mediterranean with the Lenfest Ocean Program.
"And until recently, these species were not valuable - they were caught as bycatch by boats chasing important species such as tuna - so they were declining without anyone noticing," he told BBC News.
Shark traps
There are 47 species of shark found regularly in the Mediterranean, of which 20 are top predators.
Fishermen tended to regard them as pests, according to records amassed by the researchers.
For five of the 20 top predators, the records - from traditional tuna "traps", commercial boats and fishermen using rods and lines - were good enough to show that catches had been large enough to produce a substantial decline.
The hammerhead population, they conclude, has declined by more than 99.99% over the last 200 years. Records show hammerheads largely vanished from coastal waters around 1900; in the last 20 years they have barely been seen in pelagic zones either.
The blue shark and the two mackerel sharks have also apparently vanished from coastal waters. Threshers are occasionally still caught in tuna traps; even so, their numbers across the Mediterrannean have fallen by more than 99.99%.
For the rest of the 20 top predators, records were not comprehensive enough to plot a trend, though declines were evident. Francesco Ferretti suggests that may be because their decline began even earlier, when records were even more sparse.
Studies on historical populations are rare, he said; but when they do plot declines, that should lead to listing as a threatened species.
"This study will hopefully contribute to a greater threat status for hammerheads and blue sharks, and other assessments in the Mediterranean," he said.
Conservation limits
Conservationists have long campaigned for better protection for sharks and rays, which have not traditionally been considered by the organisations that regulate fisheries.
"Historically, they didn't have high economic value, and as resource priorities and management are linked with the economic value of fisheries, sharks have never been managed - they slipped under the radar," commented Rebecca Greenberg, a marine scientist with the conservation group Oceana.
"Now, many larger shark-catching nations are taking advantage of the fact that they're not regulated; and along with the negative image that many people have of sharks, that's led to the desperate situation we have today."
What worries conservation scientists most is that the disappearance of top predators from an ecosystem can produce unexpected changes.
The apparent rise in jellyfish numbers - documented in different regions of the oceans, including the Spanish coast of the Mediterranean - may be partly due to falling numbers of predators such as bluefin tuna and turtles.
Conservation groups believe a set of measures to protect sharks worldwide, but especially in the Mediterranean - the "most dangerous area in the world" for them, according to Rebecca Greenberg - is long overdue.
These would include the policing of bans on finning - which removes fins for the lucrative eastern cuisine market - measures to reduce bycatch, and the setting of regional and global catch limits.
Med Shark Numbers Down 97 Pct Over Two Centuries
PlanetArk 12 Jun 08;
ROME - The number of sharks in the Mediterranean has fallen by 97 percent in the last 200 years, putting the sea's ecological balance at risk, a report released on Wednesday said.
The report, by the Washington-based Lenfest Ocean Program, used records such as fishermen's logs, shark landings, museum specimens and visual sightings to estimate the number and size of the Mediterranean sharks over the last two centuries.
There was only enough data on five of the 20 big shark species present in the Mediterranean to be useful to the study -- the hammerhead, thresher, blue and two species of mackerel shark, which averaged a decline of 97 percent.
"It will have a major impact on the ecosystem because large predatory sharks are at the top of the food chain," said Francesco Ferretti, the report's lead author.
Losing the top of the food chain can mean smaller fish thrive and consume more of their prey, upsetting the ecological balance. "If we lose these sharks we are going to lose this important portion of the ecosystem functioning," said Ferretti.
A report last month by the International Union for Conservation of Nature found 11 kinds of shark faced extinction due to overfishing, partly caused by booming demand for shark fin soup in Asia.
Fishers from all over the world catch and trade sharks for their lucrative fins, often discarding their carcasses, the report said, noting Indonesia and Spain are among the top culprits.
Ferretti said the practice was not thought to be common in the Mediterranean due to the small numbers of sharks now present there. More of a problem was "by-catch" -- where sharks are caught in long-line fishing meant to snag tuna and swordfish.
"The Mediterranean has been fished since Roman times, it's a historical thing," said Ferretti. "But now (modern) fishing has put big impact on the shark population." (Reporting by Robin Pomeroy)
Sharks 'functionally extinct' in Mediterranean
Malcolm Moore, The Telegraph 12 Jun 08;
Sharks are now "functionally extinct" in the waters in the Mediterranean Sea, a historical study has shown.
Researchers used fishermens' notes and archives to show that numbers had declined by as much as 99 per cent in the last two centuries.
The study, in the journal Conservation Biology, comes just weeks after a warning that half of the world's ocean-going sharks face extinction.
The scientists who conducted the study said that 47 species of sharks live in the Mediterranean, but that many of them had not been seen for decades.
They added that other predators, such as whales, turtles and large fish such as tuna, "had declined similarly" and that the entire ecosystem of the Mediterranean was at risk. Sharks help control the populations of various fish and keep the food chain balanced.
"The loss of sharks in the Atlantic has resulted in unpredictable changes to the ecosystem. Given the decline in the Mediterranean, there is cause to be seriously concerned about the effect that this could have," said Francesco Ferretti, the head of the research team.
The team looked at the populations of hammerheads, blue sharks, thresher sharks and mackerel shark. "Many historical records show the Mediterranean had an abundance of large sharks, which were considered a pest by fishermen," said the report.
"Hammerhead sharks declined the fastest. In the early 1900s catches and sightings were regular, although not common. After 1963 no hammerheads were caught or seen in coastal areas. After 1995 we found no more records," it added.
The authors concluded that sharks have been either legally or illegally fished to extinction, as fishermen sought to get rid of them. Sharks are particularly vulnerable to fishing because they breed rarely and take a long time to grow to maturity.
Another report, from the World Conservation Union (IUCN) came to a similar conclusion recently and warned that the Mediterranean Sea is "one of the most dangerous places on earth for sharks and rays".
