The Sea Dogs carried a 2-1 advantage into the third period only to allow three goals in the final frame. Saint John recorded just six shots in the third.
Saint John's power play provided some offence, going one-for-five on the night. Anthony Boucher and William Poirier scored for Saint John. Boucher also had an assist. Alex D'Orio made 21 stops in the loss.
Mitchell Balmas, Alex Breton, Alec Malo and Giordano Finoro scored for Gatineau. Tristan Berube made 28 saves in the win.
Balmas scored the lone goal of the first period. Saint John replied in the second with Boucher scoring at 3:23 and then Poirier putting Saint John in front with a power play marker at 13:58.
Some third period penalties proved costly for the Sea Dogs. At 10:29, Breton scored on the man advantage to make it 2-2. Then at 15:09 and Matt Green serving a four-minute high sticking penalty, Malo connected to put Gatineau back in front, 3-2.
The Olympiques added an empty net goal at 18:35 to make it a 4-2 final.
SCRATCHESHere is this afternoon's lineup for your #SJSeaDogs brought to you by @CantrburyDental #AlwaysWearYourMouthGuard pic.twitter.com/SJyvKoYVt7— Saint John Sea Dogs (@SJSeaDogs) December 10, 2017
The Sea Dogs were without defenceman Tyler Smith (healthy); and forwards Joe Veleno (upper body), Nick Deakin-Poot (upper body), Kevin Gursoy (upper body), Samuel Leblanc (healthy).
Saint John went with seven defencemen and 11 forwards for this game... Aiden MacIntosh and Ben Reid were both reassigned back to the MHL's St. Stephen Aces... Joe Veleno was in the building and sat with the rest of the Sea Dogs' scratches... former Sea Dogs defenceman Oliver Felixson was in attendance... Gatineau won both games of the season series against Saint John.
The Sea Dogs are in Moncton to face the Wildcats on Friday at 7 p.m.