By Stefan Lovgren
Tonle Sap, Cambodia, April 2, 2017
Some of the world’s greatest animal migrations take place on land, like the wildebeests traversing the East African plains and caribou crossing the Alaskan tundra. Other epic journeys are made in the air: monarch butterflies seeking mountain shelter in Mexico or songbirds traveling thousands of miles to reach their tropical wintering grounds.
But one of the most important treks—and definitely one of the largest, in terms of sheer numbers of animals on the move—occurs out of view, in the murky depths of the Tonle Sap River in Cambodia, where each year billions of fish of all shapes and sizes embark on one of the most incredible animal migrations on the planet.
“This is a huge, spectacular event that most people have never heard of,” says Zeb Hogan, a National Geographic fellow and host of the TV show Monster Fish on Nat Geo Wild.
Hogan is in Cambodia researching and documenting the migration as the leader of a USAID project called “Wonders of the Mekong,” which focuses on the sustainable development of the rivers and landscapes of the Lower Mekong River Basin.