Both sides went into the final round of matches winless but it was Tonga, sitting six places higher than the North Americans in the World Rugby Rankings, who seized the early initiative.
Just over seven minutes were on the clock when full-back David Halaifonua breached the try-line following an attacking scrum. Scrum-half Sonatane Takulua added the conversion before Gordon McRorie got Canada on the scoreboard with an 18th-minute penalty.
Tonga took firm control of the contest around the half-hour mark with two tries in three minutes. For the first winger Viliame Lolohea crashed over near the posts following a team move that started in the 'Ikale Tahi’s own 22, before Malietoa Hingano punished Canada for an overthrown lineout to give his side a 16-point lead.
Takulua missed the conversion and Canada ate into that advantage on the stroke of half-time as Jeff Hassler touched down to leave the score at 19-8 at the break.
Tonga extended their lead beyond two converted tries within two minutes of the restart as replacement prop Latu Talakai – who only came on at half-time – crashed over and Takulua added his third conversion.
Canada earned some reward for an improved second-half performance when Patrick Parfrey breached the Tongan line on the hour mark.
Replacement second-row Sione Vailanu added a fifth Tongan try, converted by Latiume Fosita, in the 74th minute and it proved a necessary one as Canada scored two more unconverted scores – through DTH van der Merwe and Hassler – to make the final score more respectable.
“It was a well-deserved win for the boys,” Tonga captain Siale Piutau said. “We’re just trying to get fitter, stronger so we’re ready for the tier one teams at the World Cup.”
Canada captain Tyler Ardron said: “I think we have probably finished some games well but the first half hasn’t gone as well as we would have liked. That’s something we’ll have to work on heading to the World Cup.”