Sullivan carded a 74 to finish with a four-round total of 1-over-par 289. He finished 17 shots behind winner Kevin Kwon of Meadows, B.C., who won by a record-tying 11 shots.
Winnipeg’s Scott Mazur carded a 73 on Friday to move up and into a tie for 33rd at 13 over.
Meanwhile, at the junior women’s national championship in nearby Richmond, B.C., Winnipeg’s Jenna Roadley finished in a tie for 32nd spot after shooting a final-round 85 on Friday. She finished with a 20-over-par 312 total. Winnipeg’s Winnie Hyun tied for 62nd with a 36-over total.