The world's oceans are already in a precarious state, hammered by extensive coastal pollution, climate change, over-fishing and the enormously wasteful practice of deep-sea trawling, in which heavily weighted nets dragged along the sea floor scoop up everything in their 100-metre-wide paths, including vast amounts of unwanted sea creatures, the so-called bycatch.
The only way to reverse this slide into an abysmal future is to stop fishing out one species after another to ensure there is an abundance of biodiversity in the seas, researchers have found.
It turns out that every species matters. Each species of fish plays an important role in the health and capacity of the oceans to respond to disease or disaster. That is the gist of the most comprehensive analysis of life in the oceans ever carried out, published Thursday in the journal Science.
"Whether we looked at tide pools or studies over the entire world's oceans, we saw the same picture emerging," said lead author Boris Worm of Dalhousie University.
"In losing species we lose the productivity and stability of entire ecosystems. I was shocked and disturbed by how consistent these trends are -- beyond anything we suspected."
Previous studies by Worm and others found that the variety of species has dropped by as much as 50 percent in the past 50 years in many parts of the world's oceans.
Oceans are much different than they were 50, 100 or 1,000 years ago, and much has been lost and forgotten to the detriment of humanity, Worm told IPS.
"Millions of seal-sized northern Atlantic cod, along with the now extinct Atlantic Gray Whale, walrus and sea mink (a type of sea otter) filled the oceans of Atlantic Canada not that long ago," he said.
After 500 years of fishing, these creatures are gone. And despite a 12-year ban on fishing of cod and other groundfish, the stocks of these species have not recovered and may never recover, he said.
"The fact is we don't know how to fix this," Worm said. "We have always relied on the self-repairing ability of marine ecosystems."
But there is a point of no return, the international scientific analysis warns. That species go extinct is not new, but the study shows that when too many species in a region become extinct or are too low in numbers, the ecosystem itself unravels, leading to further loss of species until little is left but jellyfish.
"The results are striking. There are clear benefits to having more biodiversity than less," Kimberley Selkoe of the National Center for Ecological Analysis and Synthesis at University of California, told IPS.
As an example of the intricacy of marine ecosystems, Selkoe explained that over-harvesting of oysters in Chesapeake Bay on the U.S. Atlantic coast brought reduced water filtration, resulting in more effluents in the water and an increase in toxic algal blooms that have had significant economic impacts on the entire region.
The new yardstick for ensuring the health of ecosystems and the environment ought to be more biodiversity, she said.
"If we don't make substantial changes soon, our wild seafood will be little more than sea squirt soup," co-author Steve Palumbi of Stanford University told IPS from an international conference on Marine Genomics in Sorrento, Italy.
Many of the economic activities along coastlines also rely on diverse systems and the healthy waters they supply, said Palumbi.
"The ocean is a great recycler. It takes sewage and recycles it into nutrients, it scrubs toxins out of the water, and it produces food and turns carbon dioxide into food and oxygen," he said.
But in order to provide these services, the ocean needs all its working parts -- the millions of plant and animal species that inhabit the sea.
Whales have been amongst the most threatened marine species and after a 20-year ban on commercial hunting, most seem to be coming back. However, there are exceptions, such as the North Atlantic Right and the West Pacific Gray Whales, which may not survive because their numbers are so low, he said.
With protection, recovery is possible for many species, which can then be fished once more. The study looked at protected areas worldwide and found that restoration of biodiversity increased productivity four-fold in terms of catch per unit effort.
But less than one percent of the global ocean is effectively protected right now.
"We won't see complete recovery in one year, but in many cases species come back more quickly than people anticipated in three to five to 10 years," said Worm. "And where this has been done we see immediate economic benefits."
But fisheries management has to move beyond mere estimates of how many fish of prized commercial species are caught to a holistic ecosystem management.
Practically, that means ocean zoning much like municipal land zoning, where parts of the ocean are off-limits to all fishing, while others can be carefully fished, and others can be open to trawling or oil and gas development, said Worm.
This has been done successfully in New Zealand and there is enough information available to set up similar zoning for all coastal fisheries, scientists say. The open ocean will also need some form of zoning but until more is known there should be an international moratorium on deep-sea bottom trawling because of the damage being done to corals, Worm said.
However, he said that Canada and other nations "lack the political will" to take action. Indeed Canada opposes a proposed UN moratorium on trawling.
"Fishing has to be more selective and much less destructive and more sustainable, including greatly reducing bycatch and to stop feeding farmed salmon fish meal," he said.
Worm recently glimpsed the past glory of the oceans at an extremely remote coral atoll in the middle of the Pacific Ocean that has never been fished.
"The abundance of species was amazing. It is a perfect natural economy with no waste," the researcher said. "It was like traveling back in time."
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Albion Monitor November
2, 2006 (http://www.albionmonitor.com)
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