A Seal Without a Sea

Picture a zoologist tackling this question seriously for the first time — and running straight into a puzzle science still hasn't fully solved. How did a marine mammal end up in a freshwater lake, cut off from any ocean by thousands of kilometres?

The Baikal seal is the only freshwater seal on the planet. It lives in Lake Baikal, in Siberia — a lake so vast and deep it holds about a fifth of all the world's unfrozen fresh water. A full-grown seal reaches about one metre seventy in length and can weigh up to a hundred and fifty kilograms. It sits at the top of Baikal's food chain — the lake's only mammal. In a single year, one seal eats around a tonne of fish: golomyanka, a translucent oily fish found nowhere else, and various sculpins.

The biggest mystery is where it came from. The most widely accepted theory: during the Ice Age, the seal's ancestors migrated inland along the river system of the Yenisei and the Angara, working their way from the ocean deep into the heart of the continent. But that's only a theory — other explanations exist, and scientists still haven't reached agreement.

The seal can dive to depths of two hundred metres and stay underwater for over an hour. It can even pause the development of its own embryo when conditions aren't right — delaying birth until better times. Pups are born in winter wrapped in snow-white fur, camouflage that makes them almost invisible against the lake ice.

Hunting on Baikal was banned in nineteen eighty. Since then, the population has recovered to somewhere between one hundred ten and one hundred thirty thousand animals. Today, researchers count them using drones.

Baikal seals can live fifty to sixty years, and females go on having pups until they're forty-five. This isn't just a rare animal — it's a living gauge of the health of the lake itself.

The world is enormous and one question is enough to start. moygid dot online.