One of the saddest legacies of the intense period of whaling following the second World War, was the almost complete annihilation of the blue whale in the southern hemisphere. Many scientists believed the species was doomed to extinction; many thought with so few whales left in so vast an ocean, that the individuals would not be able to find mates.
We now know that the voices of the blue whales can travel immense distances underwater. It may be due to this fact that the few survivors were able to continue the species.
Photo identification of individual blue whales is now being carried out by researchers in Australia, Chile, and other southern countries, with several hundred individual animals being recognized in such photo catalogs.
Additional DNA samples (which can be obtained without harm to the whales) are further addressing the question of the viability of these small populations.
It appears that the blue whale may be able to make it in the Antarctic after all, if it continues to receive protection from whaling activity. (ECO notes that there is ample evidence that past whalers often ignored IWC regulations and killed protected individuals in the vicious hunts for more and more whales.)
We also note that a number of similar studies are being undertaken to assess other depleted species of whales, including right whales, gray whales, and many dolphin species, by individual nations under the purview of the IWC Scientific Committee and the Conservation Committee.