AUGUSTA — The two groups fighting over a contentious ballot measure in Maine that would ban the use of dogs, bait and traps for bear hunting have spent $1.6 million so far to run television advertisements, according to information the Center for Public Integrity released on Thursday. The pro-ban group Mainers for Fair Bear Hunting has spent $860,500 to run nearly 2,200 ads, according to the group’s analysis of Kantar Media/CMAG research, which tracks political advertising.