You can catch fish in item form in biomes where their mob counterparts wouldn't spawn

You can, for example, pufferfish in frozen biomes or saltwater fish in land and river biomes. You can already obtain bamboo by fishing in jungles so there is a precedent for each biome having a different fishing loot table.
This might technicaly qualify as a feature request, but to me it feels like an oversight in the loot tables.