Though only the dolphin leader may be hard to overturn, Monday's opening day of the MidAtlantic Tournament out of Cape May and Ocean City, Md. was a great one for the fleet as 111 of the 127 boats involved used one of their three fishing days this week to take advantage of light winds and fairly calm seas in the quest for a $2,412,510 purse.  The toughest fish to beat may be the 43-pound dolphin boated by Restless Lady. There's also another large dolphin in second place, a 36-pounder by Blew Bayou. It only took a 38-pounder to win at the recent White Marlin Open in Ocean City, Md, and a 30-pound dolphin won at last month's Beach Haven White Marlin Invitational. Nine dolphin were weighed Monday, and another was released.   The big money is in white marlin, and it often takes a few days before an eligible white is weighed. Yet Jamie Diller of Stone Harbor got a jump on the competition with a 68-pounder on Canyon Lady. Though five other whites were brought to the scales, that was the only qualifier. A total of 108 whites were recorded by the 111 boats fishing, with 102 being released. The only blue marlin hooked was released. Just five tuna were brought to the scales, and Michael Yocco of New Providence is leading with a 113-pounder on his MJs, followed by a 107-pounder on Goin' In Deep. The Canyon Runner from Point Pleasant had the top two places in wahoo at 23 and 13 pounds before Edward Di Villa of Bayville took over second on Carol Annie II at 16 pounds.