Net losses: Humans running out of places to fish, study say

http://www.montrealgazette.com/technology/losses+Humans+running+places+fish+study/3919460/story.html

The commercial fishing industry has run out of new fishing holes and could soon face lighter nets thanks to its rapid expansion over the past 50 years, according to a new study led by the University of British Columbia.

"Sustainability is not built into our interaction with the sea. . . . We grab what we can and then we deal with the consequences. When there is nothing left to grab we have to go further to get new things," says Daniel Pauly, co-author and principal investigator of the Sea Around Us Project at UBC Fisheries Centre.

The search has pushed fishermen offshore since the 1900s, creating a no-fish-left-behind style of expansion, Pauly said.

Commercial fishing nets spread throughout the world's oceans at a rate of one million square kilometres every year through the end of the 1970s, according to the study.

By the 1980s and 1990s, the industry was eating up fishing areas at triple the rate — an annual growth rivalling the size of the Amazon rainforest.

The only untapped fishing frontiers are the unproductive waters of the high seas, the inaccessible waters in the Arctic and Antarctic, and the 0.1 per cent of the world's oceans designated as marine reserves, the study said.

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http://news.sciencemag.org/sciencenow/2010/11/earth-oceans-were-homegrown.html?ref=hp

Earth Oceans Were Homegrown
by Bruce Dorminey on 29 November 2010, 5:50 PM

Early seas. A new study may explain how Earth got its oceans.
Credit: David A. Aguilar/CfA; (inset, ocean) NASA

Where did Earth's oceans come from? Astronomers have long contended that icy comets and asteroids delivered the water for them during an epoch of heavy bombardment that ended about 3.9 billion years ago. But a new study suggests that Earth supplied its own water, leaching it from the rocks that formed the planet. The finding may help explain why life on Earth appeared so early, and it may indicate that other rocky worlds are also awash in vast seas.

Our planet has always harbored water. The rubble that coalesced to form Earth contained trace amounts—tens to hundreds of parts per million—of the stuff. But scientists didn't believe that was enough to create today's oceans, and thus they looked to alien origins for our water supply. Geologist Linda Elkins-Tanton of the Massachusetts Institute of Technology in Cambridge didn't think researchers needed to look that far.

To make her case, she conducted a chemical and physical analysis of Earth's library of meteorites—a useful analogue for the building blocks of our planet. She then plugged the data into a computer simulation of early Earth-like planets. Her models show that a large percentage of the water in the molten rock would quickly form a steam atmosphere before cooling and condensing into an ocean. The process would take tens of millions of years, meaning that oceans were sloshing around on Earth by as early as 4.4 billion years ago. Even the scant amount of water in the mantle, which is much drier than the sand in the Sahara, should produce oceans hundreds of meters deep, Elkins-Tanton reports in an upcoming paper in Astrophysics and Space Science.

Astrobiologists have been continually surprised by how quickly life evolved on Earth—within 600 million years after the planet's formation, or about 3.9 billion years ago. Elkins-Tanton's findings may help explain why. "If water oceans were present shortly after the impact that formed the moon [some 4.45 billion years ago]," says Dirk Schulze-Makuch, an astrobiologist at Washington State University, Pullman, "much more time would be available for the evolution of life, and it would explain why life was already relatively complex when we find the first traces of it in the rock record."

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