I marinate my YT and tuna bellies in teryaki sauce then cook quickly over hot BBQ. I like albacore best. The bellies have the most fat content. Some like it and some don't. To me it's like choosing rib-eye steak over filet. More fat more flavor.
I like to broil the collars at around 400 with a little garlic salt and pepper, served with fresh lemon or ponzu and green onion.
For the bellies, sashimi is always my priority. Removing the bones, membrane and skin is the hard part. Or, i'll mince the belly meat and mix it with sesame oil to make a tartare. Or, i'll mix it with some mayo, masago and sciracha to make spicy tuna. Or, I'll take the spicy tuna belly mix, roll it in shiso leaves, dip into batter and panko, and make spicy tuna shiso tempura with ponzu. Or, I'll just wrap bacon around it and wait for Tommy to slap me.
I bbq the collars with Soy and molasses as maranade.... take'em off the bbq, drizzle with that asian red pepper sweet chili sauce and nosh on em like chicken wings....
For the bellies I brine them in soy sauce/molasses/honey a little liquid smoke overnight. Let them dry for a couple hours. Then smoke them at around 120F for no more than an hour... If done correctly the meat should be just about spreadable. eat that as-is with potato chips or mash it (50/50 ratio) into softened cream cheese and spread onto your favorite cracker.....
Don't worry some of the guys on our trip waste nothing on the fish. BobbyG will give the full run down. I am sure Bert and Morfis have a lot ways not to waste fish. I told them no eating out of the bait tank. Don't get any finger prints on my new stick.
When I cook fish I try to keep it as simple as possible , too much seasoning takes away from what fish is supposed to taste like.That being said for Yellowtail collars I use some Sea Salt or Kosher Salt , cracked pepper and Brush on Extra Virgin Olive Oil refrigerate for about 1- 2 hrs , place them skin down on a hot grill , when u see the sides turn opaque turn over for about 3- 5 minutes depending on thickness and enjoy! Lemon and some Tapatio , Ice Cold Modelo Especial.
Smoking is def a good way to go -2cups brown sugar 3/4 cup sea salt garlic powder pepper and any other seasoning you want . wet down into a slurry- not liquid- with some apple juice, brine the bellies for 2 hours smoke for about 5 hours at 160 deg.
The best snack when out on the water!!