I would have immediately pulled into the nearest shoreline and affixed a gigantic treble hook onto the rear of the canoe, then attached all the rope I had in my possession to the bow.  I then would have sent my partner out to "fish the area some more" while volunteering to stand on shore and hold the other end of the rope to "pull him in" in case the beast attacked again.

It is my belief that almost any leviathan will be tempted by a large sucker...