Hundreds of peace activists prevented the unloading of an Israeli ship at the Port of Oakland Sunday by forming a picket line that was considered a threat to longshoremen who could otherwise have worked.Organizers said their goal was to delay the ship’s unloading for 24 hours in protest of the Israeli military’s May 31 open seas raid on a humanitarian aid flotilla that had been bringing goods to Gaza. The raid resulted in the deaths of nine Turkish citizens.