Well, in real life if all the nukes were launched, bascially there would be a dark coverin around the world full of radiation, so nothing is safe. Then the inland water is irradiated which could drift out to seas. Whales have to surface at sometime so they couldn't get away from it. That would probally kill them out.
I'm not sure if the airborne FEV got out into the sea. If so then they might be able to mutate, if not then they probally all died.
Then there is the possibility that sharks could have mutated and ate all the whales, that would be even more scary, sharks the size of whales eating whales that are doubled in size.
Otherwise it doesn't even matter.