WD
It depends, many areas have regulations telling you what to do. Some Places require fish guts to disposed of in the water, some prohibit it. If buried it will be dug up. I think burning it is a good idea to reduce the weight and smell of the left overs. In a good fire it will completely burn. In high use areas a garbage can is the correct thing, in true wilderness it depends on regulations, but removing protein from high altitude lakes maybe requires returning the guts and head to the environment.
Ideas?
Oh Yes, I encourage my friends not to bring fish especially canned smoked salmon into bear areas. Eating fish is ok as long as you aren't living off golden trout...

I notice that areas of high camping use have more chipmunks and golden mantled ground squirrels. Like city parks, the animal population in these areas gets a lot of food from humans. If that food source was cut off, a lot of animals would die. I've heard that urban raccoon populations can be three times higher per square mile than in a natural raccoon population in the woods somewhere.
So its sort of complex, others will have more to say...
Jim