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Topic: All About Science!!! (Read 978 times) |
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okasantina
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 Yokohama, Japan
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All About Science!!!
« on: Nov 8th, 2006, 4:24am » |
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'Only 50 years left' for sea fish
By Richard Black
Environment correspondent, BBC News website
There will be virtually nothing left to fish from the seas by the middle of the century if current trends continue, according to a major scientific study.
Stocks have collapsed in nearly one-third of sea fisheries, and the rate of decline is accelerating.
Writing in the journal Science, the international team of researchers says fishery decline is closely tied to a broader loss of marine biodiversity.
But a greater use of protected areas could safeguard existing stocks.
"The way we use the oceans is that we hope and assume there will always be another species to exploit after we've completely gone through the last one," said research leader Boris Worm, from Dalhousie University in Canada.
This century is the last century of wild seafood
Steve Palumbi
Should fish be off the menu?
Send us your comments
"What we're highlighting is there is a finite number of stocks; we have gone through one-third, and we are going to get through the rest," he told the BBC News website.
Steve Palumbi, from Stanford University in California, one of the other scientists on the project, added: "Unless we fundamentally change the way we manage all the ocean species together, as working ecosystems, then this century is the last century of wild seafood."
Spanning the seas
This is a vast piece of research, incorporating scientists from many institutions in Europe and the Americas, and drawing on four distinctly different kinds of data.
Graph of fish decline.
Catch records from the open sea give a picture of declining fish stocks.
In 2003, 29% of open sea fisheries were in a state of collapse, defined as a decline to less than 10% of their original yield.
Bigger vessels, better nets, and new technology for spotting fish are not bringing the world's fleets bigger returns - in fact, the global catch fell by 13% between 1994 and 2003.
Historical records from coastal zones in North America, Europe and Australia also show declining yields, in step with declining species diversity; these are yields not just of fish, but of other kinds of seafood too.
Zones of biodiversity loss also tended to see more beach closures, more blooms of potentially harmful algae, and more coastal flooding.
We should protect biodiversity, and it does pay off through fisheries yield
Carl Gustaf Lundin
Experiments performed in small, relatively contained ecosystems show that reductions in diversity tend to bring reductions in the size and robustness of local fish stocks. This implies that loss of biodiversity is driving the declines in fish stocks seen in the large-scale studies.
The final part of the jigsaw is data from areas where fishing has been banned or heavily restricted.
These show that protection brings back biodiversity within the zone, and restores populations of fish just outside.
Click here to see where the evidence came from
"The image I use to explain why biodiversity is so important is that marine life is a bit like a house of cards," said Dr Worm.
"All parts of it are integral to the structure; if you remove parts, particularly at the bottom, it's detrimental to everything on top and threatens the whole structure.
"And we're learning that in the oceans, species are very strongly linked to each other - probably more so than on land."
Protected interest
What the study does not do is attribute damage to individual activities such as over-fishing, pollution or habitat loss; instead it paints a picture of the cumulative harm done across the board.
Even so, a key implication of the research is that more of the oceans should be protected.
Nets on tuna boat. Image: Wolcott Henry 2005/Marine Photobank
Modern fishing methods such as purse seine nets are very efficient
But the extent of protection is not the only issue, according to Carl Gustaf Lundin, head of the global marine programme at IUCN, the World Conservation Union.
"The benefits of marine-protected areas are quite clear in a few cases; there's no doubt that protecting areas leads to a lot more fish and larger fish, and less vulnerability," he said.
"But you also have to have good management of marine parks and good management of fisheries. Clearly, fishing should not wreck the ecosystem, bottom trawling being a good example of something which does wreck the ecosystem."
But, he said, the concept of protecting fish stocks by protecting biodiversity does make sense.
"This is a good compelling case; we should protect biodiversity, and it does pay off even in simple monetary terms through fisheries yield."
Protecting stocks demands the political will to act on scientific advice - something which Boris Worm finds lacking in Europe, where politicians have ignored recommendations to halt the iconic North Sea cod fishery year after year.
Without a ban, scientists fear the North Sea stocks could follow the Grand Banks cod of eastern Canada into apparently terminal decline.
"I'm just amazed, it's very irrational," he said.
"You have scientific consensus and nothing moves. It's a sad example; and what happened in Canada should be such a warning, because now it's collapsed it's not coming back."
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okasantina
Premier Expert
Yokohama, Japan
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Study disputes cell phone-cancer link!!
« Reply #1 on: Dec 6th, 2006, 4:32am » |
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WASHINGTON - A huge study from Denmark offers the latest reassurance that cell phones don't trigger cancer. Scientists tracked 420,000 Danish cell phone users, including 52,000 who had gabbed on the gadgets for 10 years or more, and some who started using them 21 years ago.
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They matched phone records to the famed Danish Cancer Registry that records every citizen who gets the disease — and reported Tuesday that cell-phone callers are no more likely than anyone else to suffer a range of cancer types.
The study, published in the Journal of the National Cancer Institute, is the largest yet to find no bad news about the safety of cell phones and the radiofrequency energy they emit.
But even the lead researcher doubts it will end the debate.
"There's really no biological basis for you to be concerned about radio waves," said John Boice, a Vanderbilt University professor and scientific director of the International Epidemiology Institute in Rockville, Md. "Nonetheless, people are."
So Boice and colleagues at Copenhagen's Danish Cancer Society plan to continue tracking the Danish callers until at least some have used the phones for 30 years.
This so-called Danish cohort "is probably the strongest study out there because of the outstanding registries they keep," said Joshua Muscat of Pennsylvania State University, who also has studied cell phones and cancer.
"As the body of evidence accumulates, people can become more reassured that these devices are safe, but the final word is not there yet," Muscat added.
Cell phones beam radiofrequency energy that can penetrate the brain's outer edge, raising questions about cancers of the head and neck, brain tumors or leukemia. Most research has found no risk, but a few studies have raised questions. And while U.S. health officials insist the evidence shows no real reason for concern, they don't give the phones a definitive clean bill of health, either, pending long-term data on slow-growing cancers.
For the latest study, personal identification numbers assigned to each Dane at birth allowed researchers to match people who began using cell phones between 1982 and 1995 with cancer records.
Among 420,000 callers tracked through 2002, there were 14,249 cancers diagnosed — fewer than the 15,001 predicted from national cancer rates. Nor did the study find increased risks for any specific tumor type.
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okasantina
Premier Expert
Yokohama, Japan
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Posts: 2744
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Re: All About Science!!!
« Reply #2 on: Mar 13th, 2007, 4:50pm » |
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Does anyone has no interest in Science here? hello? 
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