BAR HARBOR— Fishermen have seen sea scallops stacked on top of one another in flush beds on the ocean floor and then vanish time and again throughout the decades of commercial fishing. In 2009, when stocks and landings fell concerningly low in what had been hot spots, fishermen agreed to a Department of Marine Resources (DMR) request to close some areas for three years. Then, after more than 60 meetings with fishermen, led by the Maine Center for Coastal Fisheries, in Stonington, a 10-year state management plan was adopted in 2012.