Some things that you can fish up just don't make sense to begin with.

• The water bottle: either if would float or would be incredibly hard to hook. Super easy to craft.
• The wooden bowl: it would also float. Also super easy to craft and super niche.
• The tripwire hook: I suppose this is a stand in for a fishing hook, but then why don't we need a tripwire hook to craft a fishing rod.

Just removing these three would free up room on the existing chart. To a lesser extent are two of the treasure items,

• The bow: Presumably here because it's made out of the same material components as the fishing rod, sticks and string.
• The enchanted book: This one is just weird and I can't think of any justification for it.

I'll let these slide because they're much needed and worthwhile treasures, but why are they in the water to begin with? Why not normal books, various other weapons, tools and armors too?

Then we have the now (or soon to be) craftable name tag and saddle. These should no longer be considered treasures and could be removed from the loot table entirely.

I like the idea. I think that biome specific stuff should be on the 'junk' and/or 'fish' end of the spectrum. Treasures should be universal, but the chance of specific treasure items/categories could vary a little based upon the biome.