After 100 years of disappearance, the giant whale remerges

Giant blue-grey sei whales that vanished from Argentina's Patagonian coast a century ago due to hunting are starting to flourish once again.

In the 1920s and 1930s regular whaling ships along the shores of Argentina, and beyond, saw populations dwindle.

In the last 50 years, global bans on commercial whaling have helped populations of sei and others revive.

Mariano Coscarella, biologist and researcher in marine ecosystems at CONICET added that it had taken decades for numbers to recover enough that the whales had again been sighted, which only started to happen again in recent years.

The team last month worked to fit some sei whales with satellite trackers to map their migration patterns, with funding from National Geographic's Pristine Seas project. They recorded footage of them from boats, drones and below water.

The team last month worked to fit some sei whales with satellite trackers to map their migration patterns, with funding from National Geographic's Pristine Seas project. They recorded footage of them from boats, drones and below water.

Malaysia Airlines Flight 370: The plane that disappeared in thin air