I’m no great fan of inflicting suffering on animals of any sort (with the possible exception of some football hooligans). I do however understand that fishing is a massive sport (or perhaps pastime would be a better description, if you break sweat when fishing, it’s time to talk to a cardiologist).
Anyway, today’s invention is a more effective than normal way to catch big fish.
Take a live, brightly coloured bait fish and place it inside a small transparent box full of water. Attach the box to the end of a fishing line and immerse in your body of water. The box would be hydrodynamically shaped (like a teardrop) so as to align itself fairly stably in the water current.
The movement of the bait fish would attract predators stupid enough to bite at the box and in so doing snag themselves on the nearby hook.
Naturally, I’d expect any fish not caught for food by hungry people to be thrown back (together with the somewhat perturbed, but otherwise unscathed, bait). A refinement of this system might be to have some holes in the top of the box to allow the smell of the bait to escape (as well as any vibrations given off).
If this is all thought too cruel, I’d suggest wrapping an old mobile phone in two condoms (navy seal style), whilst playing a bait fish movie in brilliant colour on the screen (most mobiles already have a piscine form factor).