The Canadian population of Common Merganser is at least moderately well monitored by four programs. The Christmas Bird Count (CBC) is considered to be the most representative, as it samples the largest proportion of the range and has high precision. It is less standardized than the Eastern Waterfowl Survey (EWS) and Breeding Bird Survey (BBS), but they have lower reliability because they provide less coverage. The British Columbia Coastal Waterbird Survey (BCCWS) samples a somewhat smaller part of the population but likely also provides medium reliability overall. The CBC and EWS show long-term moderate increases of 99% and 84% respectively. Confidence in those trends is reduced only slightly by the BBS and BCCWS, which each indicate little change instead. 

The goal for Common Merganser is to remain at or above its recent population level, based on the Christmas Bird Count. Trend data show that Common Merganser is currently within its goal range.