Chum stinkpots
Get an old style meatgrinder at a yardsale, usually has a clamp on it. Defrost mackeral well. Insert head first

I'll save a couple quart sized wax boxed juice containers to pour the sludge into. A rope through from side to side as a handle, better done after pot is filled. And into the freezer! The waxed container can then be poked full of holes as you need. I hang them over the side and sometimes use a mesh bag as well. Depending on how thawed it is, a little shake keeps a nice flow going.
One word of advice....use a designated freezer, trust me.