Don't forget the shark fin trade (another excellent example of an unsustainable harvest, and one that quite frankly is very wasteful). You know what the ironic thing is about the whales they butcher? That meat really isn't the most healthful thing to eat. What with the long lives baleen whales can live, they end up accumulating ALOT of PCBs, mercury etc in their flesh-especially as most of the stuff that bioaccumulates is fat soluble, and whales have alot of blubber on them. I don't even think it was a major part of their diet until the post-WWII occupation, if I remember correctly*.
The worst thing about this is that there are plenty of herbivorous fish-such as carp, catfish (more of omnivores, but can be raised on plant matter), tilapia, and other such fish (Personally, I've had carp meat as well as tilapia, and both are quite good). Even better is that these fish don't get to accumulate as much mercury and other contaminants since they feed on the very bottom rung of the food chain-that is, plants. A predatory fish like tuna, salmon, swordfish etc can accumulate alot of the stuff, however, since they absorb the mercury/etc. from their prey-and if the prey they eat is itself a predator of other fish, then they take up even *more* mercury, since they take in the mercury that the predatory fish got from its prey. Add in the fact that you need alot of fish to get one of these large predators to marketable or full size, and it becomes even less healthy. To top it off, since these fish are active predators and put quite a bit of energy into movement, they produce far less meat per pound/kilogram/etc of food consumed than the herbivorous fish.
*That being said, there were villages which practiced whaling, but that is more of an exception than the rule.