Anyone with a whaling license (no new lisences are given out) gets to sell a whale for more profit.
This is how it works:
They first tag the whale with an rfid chip.
Then they shoot paint bombs at it until it is sufficiently recognisable.
They then own the whale and sell to the highest bidder
on the world wide whale auction website.
This whale is saved.
The paint: what with us putting a man on the moon and everything, I imagine we can make paint that won't come off. The whale would look ugly from now on.
The sell: People can buy a whale in groups, you can own part of a whale. But rich people can actually own their own whale. This would be a status symbol. Tax deductable. Companies can own whales as a marketing stunt/image builder. People might think differently about microsoft if it owned a thousand whales.
Companies might find out a way to put their logo on the whale: use google earth to track all the google whales.
The rfid chip: I just put that in for good measure. It should really be a gps device with hartrate monitor or something like that. I imagine we could get one small enough to be shot in the outer layer of fat. Stings a bit.
Saving the whale: If any whaler should kill a whale that is already tagged and try to sell it, this would now be a crime: theft. The owner would press charges, or greenpeace would press charges in their name or something like that and the whaler is caught by police and the case is handled like any other. Thief loses his license, no new licenses are given out.
Some people still want to eat whale meat: No problem, they can buy a whale and have it for dinner. A legal act.
If whalers can make extra money for NOT killing the whale, the price of whale meat will go up and there will be no more need for them to spend money to advertise whalemeat and get people to eat it. The demand for whalemeat will drop. Eventually whales will no longer serve as food.
I think the whole procedure is difficult but not impossible. It can also be applied to other species. People and companies already own stretches of rainforrest to protect it, this idea is essentialy the same.