Conservationists in Mexico are warning of the dangers to the migrating Gray Whale. Hundreds of the giant mammals are preparing their journey back to their summer feeding grounds in the far North.

Their annual trip of 18,500km takes them from the Bering Sea between Russia and Alaska, all the way down to Mexico's western coast.

And in a few weeks, back again. It is the longest migration made by any mammal on earth. And their entire trip is spent just kilometres off the coastline.

Al Jazeera's Franc Contreras reports.