I assume your options are different when you have had your meat-preparation tactics evolve in a culture that has had easy access to ice for some thousands of years. But especially once you bring fermentation into the mix, all bets are off for how wacky any traditional process might be. (Some of the more alarming Ancient Roman fish-sauce recipes be like, "stick the prepared fish mush in a shallow pan out in the sun for a week or so, drain off the goo occasionally, mmm, delicious"—well, I'm getting that slightly wrong probably, but not in essence)
@jonsmth:
Speaking of Ancient Roman fish sauce, I believe garum specifically calls for fish guts. Fish and land animals are very different beasts, but it would seem to check out in broad strokes? If whatever bacteria or microbes they're counting on working at these specific temperatures come from, or need something from, the gut. (I of course know nothing about traditional Finnish fermentation processes.)