So, you would like to kill some people in order to save some whales? Seems a bit off.
Sink them not kill them. They'd have time to jump in the life boats, lol.
As for certain hunting being the same, the difference is domestic animals vs wild. You can't hunt them that much and expect them to repopulate alone. We always screw things up. For example we hunted the wolves to extinction in the US, and so they imported a new species of wolves, and now hunters are complaining the wolves are to aggressive compared to the old wolves and are taking the deer that they want to go hunt.
If we're gonna be implementing population control on animals, the same should be done for the human species. No women should be allowed to pump out 5 kids, 2 should be max, then there isn't such a need for so much livestock. Anyway this drifted pretty far from the op.