Bertrand played 18 games (2 starts) and had 4 catches for 17 yards and 4 carries for 10 yards, one which came on a successful fake punt against BC on July 16. He also racked up 13 special teams tackles and a forced fumble. Bertrand also started the Western Semi-Final and Western Final.
Bertand started and played 16 games at fullback and on special teams. He had 9 special teams tackles, 2 touchdowns, returned 5 kick-offs for 42 yards, 15 catches for 114 yards, and 6 carries for 17 yards. He left the game early in week 4 after he took a hit to the head. He was also put on the 1-Game Injured list for Games 16 and 17 due to a rib injury.
Bertrand was on the reserve list for the first two games of the season due to a foot injury. He recovered to start in 15 games at fullback and had seven carries for 22 yards and a touchdown, 22 catches for 207 yards, a forced fumble and 15 special teams tackles. He also had four kickoff returns for 36 yards and was named a 2009 CFLPA All-Star.
Bertrand played in all 18 games (18 starts) and enjoyed his best season as a pro. He finished the regular season with 22 receptions for 161 yards and 13 carries for 28 yards and four touchdowns. His first CFL rushing touchdown came on July 10 vs. Toronto. Always a special teams stand-out, Bertrand finished second on the team with 21 special teams tackles. He also had three kickoff returns for 34 yards. In the East Semi-Final Bertrand started at fullback and had one carry (0 yards) and one special teams tackle before injuring his leg in the 3rd quarter. He did not play in the East Final due to a deep bone bruise suffered during the Semi-Final. Bertrand was named a CFLPA All-Star.
Bertrand played in 14 games (10 starts) and had 15 receptions for 106 yards and one touchdown. Mathieu continued to be a force on special teams and recorded 12 special teams tackles.
Bertrand made his pro debut in Week 1 of the 2004 season against Montreal. He has seen action as a fullback and on special teams. He was the Eskimo nominee for Rookie of the Year.
Before switching to fullback once he turned pro, Mathieu played quarterback at Laval University. In 2003, his outstanding play earned Mathieu his second straight Quebec conference MVP award and a Hec Crighton Trophy nomination as Canadian university football's Outstanding Player. After a being drafted in the 5th round by the Montreal Alouettes in 2003, Bertrand was later released and returned to university football that fall.
Bertrand attended Laurendeau High School (St. Hubert , QC). Mathieu and his wife, Sarah, have two children, daughter Naomi and son Donovan.