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Far out to sea in the deep waters of the Pacific, a growing swirl of fish glistens just below the surface, advertising themselves as a tempting catch for a school of yellowfin tuna. With the help of internal body temperature regulators, the tuna crank up an extra spurt of speed, powering through the waves as fast as a galloping horse into the centre of the feast.
But the feeding frenzy quickly ends as a lethal ‘fish aggregating device’ (a floating piece of debris placed to attract feeding fish) ensnares the tuna. Open ocean species like tuna are often drawn to coconuts, logs, seaweed or other objects bobbing around in the sea. When these are topped with identifying flags or GPS units, the hunter quickly becomes the hunted.
So lured, the tuna are snared in the rapidly closing net of a Taiwanese fishing boat and swung out of the water in a suffocating, writhing mass. The prized fish conserve heat, generated by physical exertion, in their circulatory system, which helps them forage in cold water and digest food quickly. But in long struggles this can cause them to risk death from overheating – they literally cook from the inside with the warmth of their own body. Once on deck they are rapidly dispatched and stacked in freezers below.
Half a world away, in the warm waters of the Mediterranean, the tuna’s bluefin cousins are also snared. This time their fate is not sealed in a fast freezer. Instead, these highly migratory fish are caged and dragged through the water in tuna ‘ranches’, to be farmed and fattened until they are old enough for market.
Tuna are often touted as the world’s favourite fish, used in
Why marine reserves? Scientists and environmentalists the world over are calling for a global network of marine reserves – areas that are closed to dumping as well as to ‘extractive’ uses like fishing and mining. Within these areas there would be ‘core zones’ (home to particularly sensitive habitats or species) where no human activities are allowed.
Some coastal areas in the reserves could be open to subsistence fishing provided that it is conducted in a sustainable way with the health of the fishery in mind and only after the approval of local communities.
Nearly six years ago the UN Convention on Biological Diversity called for a network of marine reserves to be in place by 2012.
Progress has been slower than a dripping tap. According to the World Database on Marine Protection less than one per cent of the world’s oceans are now protected. Scientists propose a minimum of 20 per cent but up to 50 per cent may be required to reverse habitat degradation and plummeting fish stocks. As it is, the high seas are completely devoid of protection.
So why do marine reserves need to be so extensive and what will they deliver in return?
According to marine scientists Callum Roberts, Leanne Mason and Julie Hawkins from York University in Britain, an effective network of marine reserves should represent the full range of biodiversity. Populations in different reserves need to interact and be mutually supporting. And the reserves themselves need to be large to ensure the long-term survival of species, habitats, ecological processes and services. Also important is that the network needs to be greater than the sum of its parts. A series of isolated reserves will not give the global protection needed.
Oceans are highly complex natural systems. They contain spawning, feeding and breeding grounds – vast but delicate habitats which are home to a myriad different species and ecosystems, bound together under the sea.
Maintaining that balance is the key. And bigger is better. Allowing fish to grow large allows them to become more productive – bigger fish produce more fish. Marine reserves can benefit adjacent fisheries both from the ‘spillover’ of adult and juvenile fish beyond reserve boundaries and by the movement of eggs and larvae. Inside the reserves, fish and other sea creatures increase in size and individuals live longer.
Marine reserves could also benefit migratory species like tuna and sharks if they were set up in places where these fish are highly vulnerable – such as nursery grounds or spawning sites.
One of the primary reasons for creating marine reserves is the preservation of fish stocks. But reserves are also seen as essential to protecting the global marine environment from pollution.
26 N E W I NT ERN A TI O N A LIS T A P RIL 2010
Climate change and oceans Healthy oceans can curb the effects of global warming. Scientists have shown that robust marine ecosystems act as a giant sponge to soak up the additional CO2. Another good reason for supporting a network of global marine reserves.
l In 2002, the 500 billion tonne Larsen B ice shelf in Antarctica, which covered an area twice the size of greater London, disintegrated in less than a month.
l In 2005, the British Antarctic Survey announced that 87 per cent of the area’s glaciers have retreated over the past 50 years. In the past 5 years, the retreating glaciers have lost an average of 50 metres per year.
l The entire Antarctic ice sheet holds enough water to raise global sealevels by 62 metres.
l In July 2005, independent scientists aboard the Greenpeace ship Arctic Sunrise discovered that Greenland’s glaciers are melting at an unprecedented rate. The Kangerdlugssuaq Glacier on the island’s east coast is retreating at a rate of 14 kilometres per year.
l Greenland’s massive ice sheet locks up more than six per cent of the world’s fresh water. If the ice were to melt fully it would cause sea levels around the globe to rise by over six metres.
everything from cat food to high-class sashimi. The demand is endless but the supply is clearly finite. The much-publicized health benefits of a low-fat, high-protein diet have resulted in an insatiable global appetite for tuna. In the last 50 years, 90 per cent of big predatory fish like tuna have vanished – wiped out in one generation.
Overfishing is the curse of every ocean and almost all fisheries. According to the UN Food and Agriculture Organization, three-quarters of all fish stocks are in trouble, in decline, or struggling to recover from exploitation. More and bigger boats are chasing fewer, smaller fish – reaching far beyond their home ports and all too often into the waters of other countries less able to compete. The European fleet alone has a catch capacity two to three times greater than its seas and oceans can sustain. Floating factory ships can stay at sea all year round. The Annelies Ilena, newly built and launched just a few months ago, can catch a third of a million tonnes of fish a year – enough to supply double the entire yearly fish demands of Hong Kong.
And then there are the pirate fleets from countries like Thailand and China that take up to 19 per cent of the global catch. In some regions, like West Africa, this figure is substantially higher. Billions of dollars of illegally caught fish are served up on legitimate plates worldwide as pirate boats launder their catch through insufficiently monitored ports or by transferring to so-called legitimate vessels far out to sea. The high price for key species like bluefin tuna and Patagonian toothfish are white gold for the pirates. A single bluefin can fetch as much as $100,000 in Tokyo’s main fish market.
Local fishing communities have no hope of competing. Fisherfolk have little choice but to work the foreign boats in their own waters and watch as vital food is frozen for markets abroad or wasted, thrown back dead or dying as unwanted ‘ bycatch’. Industrial fishing nets can be the size of a football pitch, so-called ‘ long-lines’ can stretch for more than 100 kilometres, barbed with thousands of hooks. Levels of by-catch can be up to 90 per cent of the haul. Sharks, turtles and dolphins are indiscriminately snared. Other extreme fishing methods, like bottom trawling, literally tear up the ocean floor as vast nets with giant rollers wipe out entire habitats and species.
Where the wild things are no more, fish farming and ranching is becoming more prevalent as a solution to over-fishing. But the lesson of the Mediterranean tuna is testament to the flawed process, regardless of the target species.
Tuna are migratory – a round trip of 18,000 kilometres is the norm for some. In the Mediterranean the juvenile tuna are caught and penned in giant cages, swimming in endless meshed circles as they are dragged across the sea to tuna ranches for artificial fattening.
In order to feed the once-wild fish, more fish need to be caught. The irony of fish farming worldwide is the amount of fish it takes www.newint.org