A blue whale weights about 150 times more than a cow. Ignoring the economics of raising whales for food, I've often debated whether it makes since to start ranching blue whales for food. Even if you consider them a "higher" life form than a cow, are they really 150x more valuable life forms than a cow? Probably not. So why not create ocean ranches to breed blue whales?
Maybe you can train killer whales to work your whale ranch - orcas, cowdogs of the sea.
That option is worth exprloring if it's deemed that killing is essential for human surfvival, which I don't think is the consensus these days.
Seems more like a technical problem than anything else. I wonder how you'd go about actually doing it.