Octopusses are everywhere, from warm to cold waters. I take it the eagle was trying to fish and was in for a nasty surprise. It can be happy to have escaped thanks to human help. Even a "small" octopus has much more power in its muscles than a human, and it sure knows how to use them. I bet the eagle has some broken ribs at least.
Squids and octopuses are strange creatures but i like them, also studied them a bit. Thanks for the link.