A week after the acquisition of Mesaba was completed by Northwest, the major airline is assigning 36 of the 76-seat CRJ900s it has ordered to Mesaba for feeder service in a move that could mean the recall of pilots and, perhaps, even more hiring. Mesaba is subleasing the aircraft from Northwest, giving the regional 86 aircraft, but still 14 aircraft short of the 100 it operated a year ago.