The water south of Martha's Vineyard, including the stretch known as the MV shipping lanes, is prime tuna ground for the Island fleet and the south-side Cape boats. Bait stacks along the offshore edges and in the deeper lane water, and bluefin and other tuna follow it through the season.
The ground
Fish the edges, breaks and the deeper water along the lanes, keying on bait and temperature. This is more open, deeper water than the inshore banks, so reading the ocean matters.
How to fish it
Trolling to find fish along the breaks, then jigging and popping what you locate. As with the shipping lanes anywhere, keep an eye on commercial traffic.
Tip South of the Vineyard, the bait and fish relate to temperature breaks and the lane structure. Do your homework on sea-surface temperature before you run, and troll the breaks where warm and cool water meet.