The strange part is that the species is not common in Russia. In fact, National Geographic lists only one continent where the turtles inhabit natively: North America.
Why was this "Bowser" turtle so far from home?
An article on the Huffington Post speculated that the animal could have been abandoned by an owner who didn't expect the turtle to grow so large. The article also noted the possibility that "the Chinese are breeding alligator snapping turtles for eggs and meat on the other side of the river."
This turtle must have been struggling to care for himself in a land where no other alligator snapping turtles live in the wild.