by Daniel Stone 

Catchy, no? Too bad it’s all lies. There aren’t too many fish in the sea: we've eaten them.

You might call it a war on fish—some scientists and ocean specialists do. At current capacity, the world's fishing fleet could catch four times more fish each year than are actually alive in the oceans. This sad fact is the central point of a new documentary released today, End of The Line, an astute, powerful and discomforting look at what we've done to the world's oceans.

In every part of the world, fishing vessels hunt edible fish. Yet history has shown that countries that pursue certain species often have to deal with a jarring and permanent effect on their food supply. In the early 90s, Scottish and Canadian fisherman caught the populous North Atlantic cod until there were literally none left. The species was driven to such low numbers, it hasn't been able to recover, and as a result fishing communities had to shut down. Populations of the salacious Blue Fin tuna that migrate from the Atlantic to the Mediterranean have decreased by 80 percent in recent years. Advocates against overfishing have accused Mitsubishi, the Japanese car maker that's also among the world's biggest funders of industrial fishing, of stocking up the species in freezers in anticipation of there being none left. (The company claims it just wants to keep "a steady supply.")

According to a study published in 2006, scientists expect that the stocks of all fish consumable by humans will have completely collapsed by 2050. That's unfortunate for purveyors of sushi in swanky restaurants, but even more damaging to the millions of coastal inhabitants on the west coast of Africa and coastal parts of Asia, who rely on fish as a staple. If the fish disappear, so do they.  Beyond culinary and sustenance issues, a lack of fish paints a pretty bleak environmental  picture too. The diversity of the ocean and the things it does for us—soak up CO2, temper our climate—depend on diversity in the water. "It's negotiating with biology, and you just can't do that," says Charles Clover, the author of the book The End of the Line, on which the film is based.

The solution, says oceanographer Sylvia Earle, is to think differently about how we think about fish. Not just as food, but a central element in the fabric of biodiversity. In other words, if wild fish go, she says, humanity won't be too far behind.

So must we surrender our salmon? Not quite. Sustainably harvested fish is a growing industry, with impressive success among Alaskan fisherman in the north Pacific. This guide, from the folks at EarthEasy provides resources for sustainable living, gives a rundown on which fish are okay to eat and which are threatened or endangered. And we should throw a shout out to Walmart (I know!), which has committed to a target of only selling sustainable fish. Protecting fish populations, it turns out, can make for pretty good business.