Frequently, of course, the answer is "First Nations paddlers in traditional boats, a long, looooooong time before the Europeans came." But there are other answers as well, particularly when one leaves the "first" aspect behind and asks instead how many people have paddled a particular Canadian river in recent times -- such as the last hundred years or so. Or we could ask, which Canadian rivers did a certain person paddle between 1960 and 1975?
Frequently, of course, the answer for the southern rivers is, "Lots!" But for the northern rivers, there's a managable number of paddling trips that have been recorded. There's a dandy reference book listing paddling trips taken into the rivers of the Canadian North. At the Greater Victoria Public Library, we've got a copy of Canoeing North into the Unknown - A Record of River Travel: 1874 to 1974.
The authors are Bruce Willard Hodgins and Gwyneth Hoyle, and their large paperback book was released by Natural Heritage/Natural History Press in 1994, I believe.
This is one humdinger of a reference book for Canadian paddlers! It is a recommended read for anyone planning a trip into the Canadian North. I've even found it useful when planning a trip on the Red Deer River, which is too far south to be listed. You can look through the listings by area and river and date. There are terrific line maps by Dale Dompseler in each section, which have a great appeal for map fans or anyone bewildered by four-coloured atlases with contour lines. There are several excellent photographs. The bibliography is very useful. There are also separate indexes for people, river and lake names and even organizations, as other reviewers have noted.
It is very Euro-Canadian-centric, if that composite word makes any sense -- the use that First Nations people made of these rivers from 1874 to 1974 for their own purposes is largely unrecorded. But I am pleased to note that the authors of the book have an acknowledgement page giving respect to the First Nations people who still use these rivers and who between 1874 and 1974 were usually the unnamed guides and paddlers enabling the "explorers" to travel in the north. Wherever possible, the authors have listed any of these First Nations guides and paddlers by name. The authors acknowledged their debt as Canadian paddlers to the First Nations paddlers whose names were rarely recorded in the past.
If you're looking for a list of who has made a recreational trip on all the navigable parts of (say) the Porcupine River, this is a good place to start. And it's easy to end up reading the entire book. I'll quote from a review written by Michael Peake for Che-Mun and published on-line by All About Canoes website at this link:
The year 1874 was chosen as a staring point since that marked the first year of northern travel by the Geological Survey of Canada which gave us many northern pioneers, such as the Tyrrells and A.P. Low. Their closing year marked another kind of northern audit - The Wild Rivers Survey, which produced those rectangular booklets now out of print and often replete with errors.
If you can't get to a copy at your local public library, ask them to add one to the collection. If you can get a copy of your own, even better!