Both fish and bears enter a kind of hibernation referred to as "torpor" True hibernation means that the animal is in such a state of inactivity that even things like loud noises or being touched will not wake them, as if they were in a coma. In true hibernators, their bodies have completely shut down all but the most essential of functions – the heart rate will slow down by as much as 98%, metabolism drops by about 99%, and in mammals body temperature will plummet to match that of the environment, focusing only on keeping the internal organs warm enough to function at the minimum capacity necessary. Torpor is different, and is a more temporary state where the animal is only asleep for most of the time. They can be woken up by intervention or on their own to move around or 'stretch their legs' so to speak.
Bears do not actually hibernate based on the traditional definition of hibernation – they’ll wake up periodically, move about a bit and perhaps even venture out for a drink. During their 'hibernation,' their body temperature doesn’t drop extensively, and heart-rate and metabolism slows but not to the extent of a true hibernator. Instead, bears enter a short-term state known as “torpor.” Torpor can be described more so as a state of lethargy in which the organism doesn’t move around much or may appear to be asleep in some cases, but they’ll “wake up” periodically to warm up a bit (in the case of fish, by moving to water that may be slightly warmer), forage for some food (because the metabolism doesn’t slow to the extreme degree of hibernation), or simply due to some form of disturbance. This is why you may see fish up and moving around even in the dead of winter. This isn't a cause for concern, unless you see them all congregating around a hole in the ice. This likely means the fish aren't getting enough oxygen down below.
