It is almost impossible to diagnose plant issues from a couple of online photos but Verticillium wilt - to which maples are extremely prone - can cause similar branch die offs. However, it needs a plant pathologist to correctly diagnose and I have no idea how one accesses those in Canada. Here, it would be the county extension service.

maples are in very tender growth right this minute i the great lakes area.. they were bare a week ago....

frost is possible this week ... if it freezes. maple leaves can be damaged ..

there is no way to tell what happened in previous years ..

these pix look like fast emerging .. very young ....maple leaves ...

too bad about the power lines in the tree ...

were you hit with the wet snow and ice storms we got west of detroit...

ken

Hi Ken, thankyou for your reply. The power lines are actually pretty far away from the tree... just and angle of the picture. We did get a pretty hard winter but this has happened for the last few years, same symptoms. I removed some of the lower branches in the very early spring to see if that would help. I think it may be what the first person mentioned 'Verticillium wilt'. I would like to give the tree the best chance of recovering.

If it is verticillium - and I'd want to confirm that before making any big decisions - then 'recovery' is not really an option. While the tree may continue to live for a good number of years, there is no cure for this pathogen and it will eventually prove fatal.

I should also note that the decline can also be very fast, with the tree dying in a matter of days.