Are dolphin and whale numbers worldwide stable?

Dolphins and whales have a long gestation period – about 11 months and they can nurture their young for years. They are not prolific breeders. The Southern Atlantic Blue Whale has yet to recover from the devastation wrought on that species by rampant over-fishing. Out of perhaps 311,000 Antarctic Blue Whales about 2,280 are left, or about 5%.
Despite a 20-year moratorium on whaling they have yet to come back in any significant numbers. In the 1964-65 killing season 5 catcher fleets of Japanese whalers could not find a single blue whale. As a result the Japanese whalers rented out whaling base stations from Chile, the winter home of Antarctic Blues and wiped out every one they could find. Chile has recently declared all of their territory waters a whale sanctuary.