It's a very broad question. It would depend on the type of spill, the size of the spill, and where it occurred.
The ship-source pollution regime within Canada makes the polluter responsible. The polluter ultimately is the first line of defence against the spill and then coast guard and local volunteers would come in afterwards. There are too many variables. If it were a spill in ice versus a spill in open water, the size of the spill, and the type of substance spilled would all affect the response and the complexity.