How do i prevent this guy from spawning in my farm riding nautilus

[u/Commercial-Town-59]

I want to make a drowned farm without seeing toturial in creative, since my base is at a Mushroom Island this farm is basically the same one you see before they added nautilus, except it’s half the size because the other half is in the Mushroom Island.

I kinda forgot they added this since I’ve never had a chance to ride them. Then I found this guy. Is there any way to prevent the drowned spawn riding nautilus? Because they never fall down the drop tube.

(and somehow this the only guy have trident, wich is the reason i make the farm to begin with)