I know of no party boats that go just for tuna. sometimes this time of the year the captain may throw a small pollock or cod over the side while at anchor just in case. There are a few charters but of course they cost a lot more then a partyboat. There are a few partyboats that make the run to the canyons from southern NE and Montauk. I have been on the Yankee Captains boat tuna fishing and it is ok although a little crowded.