DAVIS, CA.  UC Davis captured the first three bouts then held on as they defeated Southern Oregon, 17-15, in the wrestling season opener for each team Friday, a match held outdoors on the UC Davis quad before 537 fans. In all, five Aggies came away with victories.    Senior Mark Maben put the Aggies up early with a decision at 285 pounds. Freshman Tommy Schurkamp, wrestling in his first collegiate match, made it two-for-two as he defeated Nolan Harris.    Urijah Faber then picked up a 17-4 win, giving the Aggies a 10-0, team score lead. Two more victories by UC Davis, Burt Pierson at 157 pounds and Adrian Garcia at 174 pounds, gave the Aggies their final points.    "It's a good way to begin the season with a win against a tough team," said Aggie coach Mike Burch. "I thought our conditioning looked good and we wrestled some smart matches.    "Burt Pierson stood out today. He was very active throughout his match, as was Tommy. For his first college match, I thought he wrestled real well."    UC Davis next will be in action when they travel to Oregon for a November 10 match.