[hoopleheaded]

If those bits were removed in homes they are almost always going to be wasted without municipal composting, and even that is still wasteful. If they are removed at scale (no pun intended) there is a much higher likelihood that they will be used as a byproduct in pet food or fertilizer or something.

[cheese_goddess]

I'm talking about the skins, heads and tails of fish that have no business being removed because they're edible and nutritious. I think you 're talking about the guts, that are almost always thrown out anyway.

Food waste starts with cultural norms that make some foods taboo, essentially. Like for example "offal" as the perfectly edible entrails of ruminants are derogatorily known.