Predators of the Deep
Mankind's frightening and sometimes delicious fear of them aside, the predators of the deep are in dreadful decline. The reasons are various but mostly can be placed squarely in the area of peoples' acquisitive ignorance. Just as elephants have to be protected because people see great value in the ivory of their tusks, and leopards and tigers have extraordinary appeal to humans because of their animal nobility and we wish to preserve them as wonderful animal specimens, yet come up against the illegitimate harvesting of them for their parts, it seems we have to enact laws for the same protective purposes for sharks.Throughout much of Asia, shark fin soup is seen as a symbol of wealth, served to eminent elites of society as a sign of respect. A pound of shark fin can be had for as much as $300 U.S. And since the entire shark is seen to have little value as a food source, the bodies are discarded and only the fins taken; 95% of the animal is considered waste. One hundred million sharks are killed every year, and this tragedy of the ocean deep is little observed or recognized for the environmental upset that it represents.
Sharks, unlike baby seals are not cute. Their presence evokes fear and revulsion. Photographs of sharks invoke instinctive visions of their great teeth tearing hapless human swimmers apart. No humane societies and animal-rights activists have as yet undertaken the wholesale rescue of sharks. They are seen by humankind as pure predators, dangers to unwary humans. But all those various species of shark are also beautiful works of nature and their removal from the world's oceans will result in a serious imbalance of ecosystems.
Studies by the recently-deceased Ransom Myers and Boris Worm, biologists out of Dalhousie University in Halifax point to a stupendous decline in the population of Atlantic sharks - by as much as 89% since 1972. Great white, hammerhead and bull shark populations have also declined in dramatic numbers. Overall, oceanic predator populations are estimated to have declined by 90% in the past 50 years. There is some international recognition of the dissonance between such harvesting and the natural imbalance of ecosystems as evidenced by the ban on shark-finning by 17 countries.
But the demand for shark fins is increasing, not diminishing. Chinese drugs, medications and special foods often call for exotic bits and pieces of animals for which whole animals are relinquished in the harvest of particular portions. Furthermore wholesale fishing techniques where fishing lines with baited hooks extending 80 to 90 kilometres in the ocean, target species indiscriminately. We waste an estimated 54 billion pounds of fish annually which handily explains why fisheries worldwide are expected to collapse by 2048.
Studies out of Dalhousie University suggest the removal of large sharks and predators from the ecosystems result in early warning signs of ecosystem collapse. The phenomenon is labeled a "top down" effect, where the removal of one element in the chain has an inexorable effect on the entire chain of the ecosystem until total collapse has been achieved.
The example of the diminishing presence of Sea otters hunted for their pelts resulting in an explosion of urchins, their main food source, is a case in point. The urchins in their turn fed omnivorously on the kelp forests, the breeding grounds of Pacific herring. The resulting scarcity of herring meant that populations of whales, dolphins, sea lions, sharks and other large fish were nearly eliminated. Cause and effect; a total upset of nature's balance.
The study by Ransom Myers (Science, March 2007) and Julia Baum demonstrated that the absence of sharks from the Atlantic coast has caused some of their food populations such as smaller sharks, skates and rays to proliferate in such numbers that they destroyed the population of mollusks - in the process wiping out centuries-old fisheries.
All to say that we've been responsible for wiping out the top predator from every ocean, one that has balanced the ocean ecosystems for over 400 million years. As a result the entire food system has been knocked a-kilter. This effects not only aquatic species of all types and sizes and functions, but also impacts on human fisheries.
Yet another way in which humankind has profligately used, misused and spoiled ecosystems, creating a major imbalance where aquatic life-systems formerly well balanced by nature's design are now fatally imperilled. We have to design a system whereby we don't continue exploiting and despoiling those very ecosystems that support animals who share this planet with us.
We can most certainly do a whole lot better as a species among species than we have up until now. The signs of imminent collapse are there, the ultimate destruction of viable life-forms all of which are intertwined in nature's holistic steady state are yet another signpost in the kind of environmental decay our arrogant and thoughtless waste has brought us to.
There is a new film recently released which documents the plight of our ocean predators, a Canadian documentary produced by biologist/filmmaker Rob Stewart: Sharkwater. (www.sharkwater.com)
Labels: Environment
posted by Pieface @ Friday, April 06, 2007
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