The Florida Keys have a strong population of blackfin tuna just about all year, but in the summer months you’re going to find them with regularity in one of three locations: The Islamorada Hump, The Marathon Humps also known as the 409s, and the West Hump. As a rule, the smaller fish will be on the Islamorada Hump which is the size of a football field, while the Marathon Hump is actually two humps about 200 yards long each and the West Hump is about 900 yards in circumference and is out deeper than the others in about 700 feet of water.
As a rule, blackfin tuna bite best in low light conditions, so if you’re specifically targeting these fish you want to be on the water before dawn and in your fishing spot when the sun comes up. What a lot of bluewater anglers will do is leave the dock in the dark, fish tuna at first light, and then look for dolphin and wahoo in the middle of the day. That bring said, the tuna tend to bite will into the morning and also again in the late afternoon on the Marathon and West Humps, and they’ll bite all day long on cloudy days in all three places.
There are two tactics to targeting blackfin tuna: Trolling or live chumming. Both are effective ways to cover water and catch fish.
When the fish are small, it’s sometimes better to just troll and cover a lot of water because you can continuously go back and forth over the hump. There’s going to be a lot of current on the humps, so whether you troll or drift, you’re going to go over the area quickly. When you’re trolling and get to the drop off the hump, you can immediately spin the boat and circle the baits back around for another pass so that you’re constantly presenting baits on top of the hump.
For trolling, you’ll want 20 to 30 pound rods with 40 pound fluorocarbon leader an small, dark colored feathers. Blackfin tuna can be boat shy, so you want to put your baits a good ways behind the boat, and always shotgun one bait way back right down the middle of your spread. If that bait is the one that regularly gets the bite, then move the entire bait spread farther away from the boat.
Live chumming requires a good livewell and a supply of live pilchards which you catch in a castnet along the shorelines of the Keys and around the bridges. You’ll see the pilchards dimpling on the surface when it’s calm and seagulls or pelicans diving on them during the day. The pilchards are two to four inches in length, and you want to catch as many as your livewell will hold.
Then run offshore to the humps, get on the up-current side, shut the engines down and drift over the humps. You’ll want to use 20 to 40 pound spinning gear with 25 or 30 pound fluorocarbon leader. You’ll want to use the heavier tackle because you really need to lean on the fish because there will always be a good number of big sharks in the area looking to eat your tuna before you can get them in the boat.
As you start your drift, scoop up a net full of pilchards and throw them over. Then put out two or three rods baited with live pilchards on a stout 2/0 circle hook. You’re not really chumming as you drift, because the drift is so fast you’ll quickly drift away from your chum baits. You want to chum before you drift over the hump and get your baits out, so that when the chum and hooked baits get on top of the hump the tuna will rise to the surface to eat them.
As you drift past the hump, reel in the lines, start the engine and move back up-current of the humps and do the drift again. The average blackfin tuna on the Islamorada Hump is going to be four to ten pounds. The average tuna on the Marathon and West Humps will be 20 to 30 pounds.Captain Tips