I usually melt the lead off as I go, holding the hook with pliers and dipping just the lead head in the pot and dropping the hook on the table to knock any remaining lead off. This keeps from having lead residue all over the hook.
I’ve read somewhere that the hooks would float to the top if dropped into the pot, but I have never tried it.
If you have never had it happen, a piece of wire or hook stuck in the outlet of a bottom pour pot makes a big (and dangerous) mess!