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Enjoy your salmon and tuna now, seafood lovers, because whoever lives until 2048 or so will find a world completely depleted of the fish we now put on our plates. Come to think of it, don’t eat up—that’s the gist of The End of the Line, Rupert Murray’s adaptation of Charles Clover’s book that explains the crisis of overfishing and how it may soon devastate Earth’s ecosystem and change our diets for good.

Ted Danson stiffly narrates this documentary, which is informative, alarming, and yet a little dry in its singular message and barrage of statistics. Several experts from around the globe are interviewed about the limits of the sea, our view of which, as the voice-over tells us, has always been that it is “huge, beautiful, and inexhaustible.” Yet the cod that used to be practically bursting out of Nova Scotia waters are now near extinction, as are the delectable bluefin tuna that high-end restaurants serve and cooking-show hosts drool over. The small-time fisherman in places such as Senegal have relatively tiny eco-footprints, but they can’t compete with the massive-harvesting technology of foreign boats. The unsurprising heart of the problem, the film claims, is greed and tummy-rumbling arrogance. Screw sharks: Danson tells us that mankind is “the most efficient predator our oceans have ever known.”

So what to do? According to Callum Roberts, a professor at Britain’s University of York, “we need to turn back the clock 200 years.” Assuming that’s not possible, the answer is immediate and widespread activism whether you’re the head of a corporation or a couple whose date night includes a sushi stop. Like the recent Food Inc., The End of the Line both makes suggestions and points out the efforts of those in the public eye: Wal-Mart again looks like a hero, making an effort to sell only sustainable fish. Chef Jamie Oliver no longer cooks with bluefin. And some restaurants put a notice next to their descriptions of near-extinction dishes, like a black box on cigarettes.

Along with its lesson, the film offers startling imagery, both gorgeous and stomach-turning. Bluer waters you’ll never see, and they’re teeming with multicolored and jaw-droppingly exotic occupants. But there are also scenes of slaughter: Fisherman standing in bloodied seas as they slice into their catches or nets full of squirming fish struggling to stay alive. Although the ominous music during the latter sequences is overkill, The End of the Line mostly does a fine job illustrating the bleakness of a fishless world.