here is one link to the black bears in ely, mn:
http://www.bearstudy.org/website/
(cup and paste to get there, if it doesn't automatically link) this organization has done the same kind of thing for years. they don't have to tranquilize the bears to weigh them, take blood, put on collars, etc. it is based on trust and reading the bears' moods. they are not tame--they have accepted the researchers over time, and with vocal cues from the humans involved.