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AnimalsNature

Ghost Nets Further Stress Overfished Oceans

A turtle meets its fate in a ghost net

Oceans in the 21st century – overfished, mismanaged, played out

The world fishing fleet is now two or three times what is needed to take the available ocean catch and sustainably manage global fisheries.  More than 100 million tons of fish are caught in fisherman’s nets every year. Yet researchers say that in the North Sea it now takes 17 to 20 times more effort to produce one ton of fish of fish in 2009 than it did in 1900. “They are sweeping up crumbs from what used to be a breadbasket,” says marine ecologist Boris Worm of Dalhousie University in Halifax.

But more people are vying for those crumbs. With one billion people depending on fish as a key source of their daily protein, the scale of industrialized fishing has pushed marine life to the edge. More than 70 percent of world fisheries are either “fully exploited,” “over exploited,” or “significantly depleted.”  The spectacular collapse of the cod fishery off Newfoundland decimated the fishing industry there, leaving 40,000 fisherman and fishery workers without work. Cod fisheries in the North Sea and Baltic Sea are following suit and nearing total collapse.

Top predator species, a key indicator of ecosystem health, are vanishing. Populations of shark, cod, tuna, swordfish, marlin, halibut, and flounder have  been depleted by as much as 90 percent in some areas – fished-out since the start of industrialized fishing in the 1950’s. The disappearance of these top-of-the food chain species disrupts entire ecosystems, leaving lower species – like jellyfish – growing in numbers. Ever try to eat a jellyfish?

The oceans – and the life within them – are in peril. And they are haunted by ghosts.

Killer ghosts wandering the ocean

The enormous toll on the oceans is made even worse by waste and neglect. According to a 2009 study co-authored by WWF, nearly 40 percent of the annual global catch – some 38 million tones of fish – is “unused, wasted, or unaccounted for.” As much as this bleak outlook turns the stomach, there is an even more insidious devastation occurring in the world’s ocean – an unseen, silent, and  indiscriminate killer: ghost nets.

The occurrence of ghost nets prowling the ocean waters isn’t new. But given the scale of industrialized fishing combined with new synthetic gillnet – designed to last a century or more without deterioration – ghost nets only serve to exacerbate the wasteful destruction and mismanagement.

Writing recently in Forbes, Conor  Friedersdorf describes in awful detail how fishing trawlers lose or abandon 760 miles of these high-tech nets every year. Left adrift and weighing several tons (a single net can stretch miles in length) , they slowly drift to the bottom of the sea, catching and trapping all sea creatures in their wake, eventually settling and “scrubbing” the sea floor. Decomposition, time and the scrubbing action eventually consume the net’s catch – wasted and unseen – allowing the net to drift upwards to begin the process all over again, in an endless cycle of catch, consume, purge.

According to Callum Roberts, author of Unnatural History of the Sea, between 3,600 and 5,400 miles – miles – of gillnet are in continuous contact with the ocean floor just in the North Sea.

Some of these nets are found and recovered, but the process of retrieving the nets from their ghostly existence requires a long distance boat, a team of trained divers armed with rust-proof knives and scissors, and a lot of time. Needless to say the vast majority of these ghost nets remain in the say trawling unguided from one wasted catch to the next.

Seafood for the conscious consumer

It is a despairing scenario, but not one without hope. It must begin with awareness and conscious consumption of seafood. It may not seem like near enough given the scale of what has just been laid out here, but it is a beginning – and vital.

For more information on how best to consider your seafood options, seafood guides are readily available, including these two from the Blue Ocean Institute and Overfishing.org.

http://www.youtube.com/watch?v=FZU-hvcCxqQ&NR=1

Image credit: National Oceanic and Atmospheric Administration




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