I have started receiving emails for issues I am watching, and there seems to be no way to unsubscribe from them. I tried looking in my user profile, under Manage Issues (I'm not subscribed to anything there), I even tried logging in to Atlassian to change settings but my account didn't exist there so I tried creating one, but I can't tell if it's linked to this bug tracker or not. At this point I'll probably just go and stop watching all my issues.
In order to stop getting email notifications you do indeed need to stop watching reports. There is a setting to turn off "autowatch" which will stop you watching every report you comment on.
Profile -> Preferences -> Little pencil to the right -> Autowatch -> Set to "Disabled"