The most common statement that I get as a captain and deckhand is "This live bait thing for tuna doesn't look too hard, I can do this." My usual response is its actually a lot harder than it looks and I leave it at that but I'll tell you guys some of the secrets to the game and the typical setup and technique.
As far as tackle goes, match your setup to your line weight. If the smaller school sized tuna of the summer are around, a Shimano Tiagra 30W or Torsa 40 are the ticket. I like to match the reels with corresponding rods. I like to use Shimano Talluses in 50 lb class rods for the Tiagras and Terez XH class rods for the Torsa 40. As far as line goes, I use Jerry Brown 80 lb hollow core braid with 50 foot of 60 lb Momoi hard wire topshot with about 15-20 feet of 60 lb Seaguar flouro premier leader with a 5/0-6/0 circle hook. As far as the setup goes that is it. Now on to technique.
As far as bait selection goes match what they are chasing, for summer time tuna fishing, 4 inch long hard tail jacks are hard to beat, so are Threadfin Herring. To catch the hard tails pull up to a rig and drop a #4,6 or 8 size sabiki rig with a 1.5 oz sinker as a weight. And for the Herring, cast past the schools on the surface of the water and skip it across the surface using a #6 sabiki rig.
Now that you have your bait, here comes the fun part. After you have located the fish on your sonar, set up Ur baits, hooked about half of an inch to an inch behind the eye, upcurrent of the school of fish and slow troll them around the school of tuna just fast enough to keep them away from the boat, usually less than 1 knot, about 100 yards behind the boat. Once the fish bites, slowly push the drag lever to the strike position and game on!!!
Good luck guys and catch one for me. Also if you need any advice or would like to book the offshore fishing trip of a lifetime call me, Captain Mitch Rogers of Louisiana Offshore Adventures at 504-881-0117.