I catch first year Jack Crevalle CONSTANTLY in the late Summer/early Fall off of Falmouth and the islands. I've also personally witnessed a kid pull a butterfly out of a dip net on the marshes of Swifts Beach in Wareham (Buzzards Bay). People drag nets in the eel grasses on South Cape and take seahorses too. All of this tends to be a Fall Phenomenon when the Gulf Stream hugs the MA shores. It seems that the tropicals that are carried up then head for estuaries where there is food and warmer waters. Unfortunately, from what I understand, most do not make it back to tropical waters and perish as the New England waters get too cold for them.
I'm going out next weekend to try and hit some Mahi-Mahi/Dorado/Dolphin off the ledges and canyons. Keep yer fingers crossed for me. Nothing better than grilled Mahi Mahi!!
Dave