Once there is ice, pretty much any river or tributary will have smelts. They like shallower waters along the east coast (3-4 feet) whereas they tend to be deeper along the Saint-John river and tribs (8-14 feet). I'd be willing to bet if you were to take a drive upriver from the Main South-West Miramichi once there is ice that you'd find ice shacks along there somewhere. Otherwise, drive south a little to the Richibucto river (about 30-40 minutes away), and you'll find ice shacks in various places on that river and its tribs. In fact, they are catching them on the Richibucto now, way up river where some bays are already frozen with about 5" of ice.