We have estimates of fisher densities from British Columbia for a couple of different locations. You have likely seen the following 2 publications:
Weir, R. D., and F. B. Corbould. 2006. Density of fishers in the Sub-boreal Spruce biogeoclimatic zone of British Columbia. Northwestern Naturalist 87:118-127.
Weir, R. D., E. C. Lofroth, and M. Phinney. 2011. Density of fishers in boreal mixedwood forests of northeastern British Columbia. Northwestern Naturalist 92:65-69.
There is also a density estimate ms on fishers in southwestern BC that Larry Davis and I have coming out in Northwestern Naturalist in the winter 2021 issue (121). Drop me a line if you would like a pre-print copy. The long-and-the-short is 13.1 fishers/1000 km² for that area.
Rory Fogarty is also doing some density estimation of fishers in the Chilcotin dry forests of central BC as well. I believe that he is getting densities of ~18 fishers/1000 km², but you should contact him for more details. Rory.Forgarty ~at~ gov.bc.ca.
Hope this helps.
Rich.Weir ~at~ gov.bc.ca.