Overfishing and the Decline of Fishes

The variety of species in the world's oceans has dropped by as much as 50 percent in the past 50 years, according to a study published last week in the journal Science. This can be attributed to a combination of overfishing, habitat destruction and climate change.

"Where you used to put out a fishing line 50 years ago and catch 10 species, now you catch five species for the same amount of effort. That's a recipe for ecological collapse and disaster," said one of the study authors, biologist Boris Worm of Dalhousie University in Nova Scotia.