how did some freshwater fish like sturgeon end up in far-apart places (like the Great Lakes and Caspian Sea, for sturgeon) with no fresh-water path between them?

Question

how did some freshwater fish like sturgeon end up in far-apart places (like the Great Lakes and Caspian Sea, for sturgeon) with no fresh-water path between them?

In: 1

Answer 1

At one point, big sheets of ice covered the Earth. These sheets melted and created paths that let fish move between far-apart places. These paths let fish like sturgeon travel from the Caspian Sea to the Great Lakes. Basically, It’s like nature made secret underwater roads for them.