Has anybody seen a chum go after and bite a sandshrimp?

Yes, I plunk the Green every now and then. A whole sandshrimp and spinning bobber works well. And I don't think they get "lined" this way. They'll nip at the bait like a smolt then swallow it.

YEP they sure do. Got pictures of one a few weeks ago.

prawns work too, but stay on the hook longer.

Last time fishing I saw some chum milling around and first cast a fish bit the shrimp agressively like a summer steelhead. After that couldn't get anything to bite and the chum would ignore the eggs and shrimp. I didn't get a good look at the fish. Oh well gotta get back out there and do some more fishing.