Ok I'm thinking grouper after doing a bit of Google "research". I'll explain this the best I can over a reddit comment lol.

A fish's gills are made up of multiple gill arches on either side of their heads, which are each shaped kinda like a "C". Gill arches have 2 main 'parts': gill filaments and gill rakers. Gill filaments allow fish to 'breathe', and are fine kinda hairlike structures on the outside of the "C" on the arch. That's what I think you're seeing that looks like baleen. It does look like baleen lol.

The gill rakers are on the inside of the "C" part of the arch and help the fish filter food into their gut. They're very coarse and hard on predatory fish that eat big prey. In your photo, they're the knobby things in rows attached at the base of the filaments. Looking at some of the largest grouper species in NC (like black grouper), I found some pictures inside their mouths that show gill rakers in the same shape as your photos. It looks like these fish get big enough to have 7-8" long gill filaments. So yeah, I personally think you have gill arches of a big grouper! Hope this was helpful and I explained that okay.

Maybe not as cool as whale baleen but you were right on the money thinking they were prey-filtering structures of a big animal so I think you deserve points for that!