I don't think I have an accurate estimate of how many are operating. We know that it's in the order of 40 different research stations in the north. They vary in their level of activity, from the High Arctic Research Station, which has a very large number of scientists working out of, to very small stations such as Ward Hunt Island station. Typically that has between five and 15 people working at it over the course of a season.
It's in the order of hundreds.
Of course, in addition to the terrestrial side, there are people working on the sea through the Amundsen, through the Louis St-Laurent, and through other agencies and activities.