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Overfishing and Our Finite Seas

Will sustainable fisheries save the ocean's most critical resource?

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Fisheries worldwide have collapsed due to overfishing from trawlers and other threats.

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The vast oceans of the world, stretching endlessly across the horizon, seem as infinite as time and space. But we're learning the hard way that the oceans are in fact a limited resource -- one that we're rapidly depleting.

A number of human activities, including overfishing, pollution and climate change, are wiping out important fisheries worldwide and putting an entire industry -- not to mention the food source of billions of people -- at immediate risk. Discover what's at stake and what you can do to stop the destruction of the ocean's fisheries.

Our Fisheries: A Quiet Disaster Unfolds

In Sept. 2012, the U.S. Commerce Department issued a formal disaster declaration for the once-great fisheries off the northeastern United States, according to the New York Times. The disaster was declared after populations of cod were found to be just 20 percent of what it needed to be to keep the population thriving.

The Commerce Department also declared three important Alaskan salmon fisheries a disaster: In one of those fisheries, more than 859,000 pounds of salmon were harvested in 2006 -- but 5 years later, the catch had plummeted to just 1,488 pounds.

Thousands of miles away, a disaster was also declared for the oyster and blue crab industry in Mississippi, which suffered significant losses after flooding in the Mississippi River waterway system.

These are only three recent examples that demonstrate the desperate plight of fisheries around the world -- all of which are not only critical sources of income for the men and women in the fishing industry, but also an important source of food for a hungry world with 7 billion mouths. While overfishing is partly to blame, there's more at work here.

What's Killing Our Fisheries?

The ocean's fisheries, according to the environmental group Save Our Seas, are facing 5 primary threats:

Overfishing: Trawling is an industrial fishing technique that drags a huge net across the ocean floor, weighted down by trawl doors of two or more tons each. Gill nets and drift nets -- which are illegal in many waters -- catch millions of fish, turtles, sea birds, sharks and other sea life, many of which have no economic value: They're simply killed.

This overfishing is slaughtering sea life at an unimaginable scale, one that virtually guarantees the extinction of some species. About three-quarters of the world's fish are harvested at a faster rate than they can replenish their populations.

Predator Loss: The biggest fish in the seas are also among the most popular seafood. As a result, they are being fished out of existence. A staggering 90 percent of all large predatory fish –- tuna, sharks, swordfish, cod and halibut -– are now gone. And when these species populations shrink too much, other fish populations explode, wreaking havoc on marine ecosystems.

Climate Change: As the planet warms from global climate change, the oceans grow warmer, too. This is having a ruinous effect on sea life worldwide. Colder water holds more oxygen and therefore more microscopic sea life: Once those oxygen supplies dwindle, those minute sea creatures -- a critical source of food for larger fish and sea life -- disappear, starving larger fish.

Ocean acidification, which makes ocean waters more acidic, is another result of the greenhouse gases that are linked to global warming. Higher acid content in the water is deadly to marine animals like coral and shellfish, which create shells made of calcium -- their shells dissolve as ocean water grows more acidic.

Pollution: For centuries, we treated the ocean as a garbage dump for everything from drug disposal and battleship wrecks to toys and radioactive waste. Plastics are now one of the ocean's biggest pollution problems, since some plastics take centuries to break down. Several enormous, floating garbage patches are now regular features of the ocean, according to NOAA, and they're mostly made of plastic.

Habitat Destruction: Though we haven't yet started building condos underwater, we are building them in mangrove forests and in wetlands -- two sensitive ecosystems that marine life depend on for reproduction. And our land-based pollution is flowing downstream into the oceans, creating huge underwater dead zones where virtually no marine life can live.

How to Stop Destroying the Oceans

It's easy to despair of our reckless destruction of the oceans, but there's some hope, and you can help preserve the world's seas -- and in the process, the people who depend on them.

Start by raising hell. Demand government action on issues from climate change and greenhouse gas production to pollution control to overfishing. It's an uphill battle, but it's one we can win.

Exercise your power as a consumer and make smart, sustainable seafood choices when shopping. These choices ensure the growth of sustainable fisheries. And avoid using plastics whenever possible, and reuse or recycle or compost as much is feasible.

Finally, get the word out to as many people as you can about the plight of our oceans. Even if you don't care about the environment, you probably care about the humans. And we humans need our oceans.

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