Giant blue-grey sei whales that vanished from Argentina's Patagonian coast a century ago due to hunting are starting to flourish once again, demonstrating how species can recover when measures to protect them are put in place.

STORY: After vanishing more than a century ago, giant blue-grey sei whales are being spotted again off Argentina’s Patagonian coast.The species was relentlessly hunted in the 1920s and '30s - but in the last 50 years,