Here are two statistics that are interesting on their own but scary together: 40% of the world's population relies on fish for food, but every year, 7 million tons of dead fish are tossed back into the ocean because they were too young (i.e., small) to be marketable, or simply because they weren't the species the fishermen were after. These factoids come from a video promoting a product designed to solve these problems called SafetyNet. It's an industrial fish-trawling net with a few redesigned elements to ameliorate the unsustainable fishing practices described above.
SafetyNet was designed by David Watson (currently a student in the Innovation Design Engineering joint course between the Royal College of Art and Imperial College, London) as an entry in Time To Care, a sustainability-in-design competition sponsored by Victorinox Swiss Army. The problem is simple: Huge industrial trawling nets scoop up all the wrong kinds of fish along with the "right" ones because their flawed design prevents the non-desirable species from escaping. The unwanted fish should be able to escape through the diamond-shaped holes in the netting, but dragging the net through the water pulls these holes closed. Watson's solution: stud the netting with reinforcing rings, which prevent the holes from getting yanked shut.
That's a pretty clever solution, but Watson didn't stop there. His research showed that most fish can't even see the net when they're in it, so his reinforcing rings are fitted with LED lamps that make them light up like an exit sign, encouraging unwanted juveniles to slip away unharmed. Even better: the LEDs are powered by a built-in turbine system in the ring that uses the constant flow of water to keep the batteries constantly charged — a "fit-and-forget-it" system, in his words.
You might be wondering why the fishermen can't just toss the unwanted fish back into the ocean alive when they pull the nets up. Apparently, the change in pressure kills the little dudes on the way up. Which is exactly why a design solution like SafetyNet is so crucial: unlike the old saw says, there actually aren't enough fish in the sea to satisfy human consumption. And we can't afford to empty the seas of any more fish than exactly the ones we need. Watson's SafetyNet won't magically solve the supply/demand problem, but it will make our current impact on the ocean ecosystems a lot less needlessly destructive. Which is a damn good start.