3. Try Artificials: This is a perfect situation for jigging, and heavy metal jigs like butterfly jigs work great. "Use a heavy metal jig, but don't strike the bite on the way down," Trosset says. "You want to use a jig weighing 2 ounces or more, and get it to the bottom. Then, just jig it up 10 or 15 feet, not all the way up. The shrimpers are usually in 80 to 100 feet of water, and you're more likely to hook a blackfin if you leave the jig deep."
Another trick involves large floating plugs like Rapalas or Bombers. "For some reason, they like orange plugs," Trosset explained. "Throw a 7-inch or larger plug out to the edge of the school of fish and just let it sit there; don't move it at all. The tunas will whack the crap out of it."
Of course, this style of fishing also lends itself perfectly to fly-casting and virtually any other type of casting tackle; it's just that with general artificial fishing you will inevitably hook lots of bonitos in addition to the blackfin. The specialized techniques mentioned here help you target blackfin exclusively.