The Canadian population of Lesser Scaup is directly monitored by three programs, and jointly with Greater Scaup by two others. Only the Breeding Bird Survey (BBS) has medium reliability, based on sampling over half of the breeding range and having intermediate precision. It shows a moderate decrease of 36% relative to 1970 levels, with almost all of the decline occurring in a short period from 1996 to 2003, and little change since then. The Christmas Bird Count (CBC) also offers good coverage but has lower precision. Although it shows more interannual variability, the long-term trend of nearly -25% is relatively close to that of the BBS. The British Columbia Coastal Waterbird Survey (BCCWS) samples a smaller part of the population, and over a shorter period, beginning only in 1999; it indicates a large decline of 88% over 20 years. The Waterfowl Breeding Population and Habitat Survey (WBPHS) indicates a long-term decline for Lesser and Greater Scaup jointly in western Canada, and likely reflects Lesser Scaup trends well, as Greater Scaup is limited to the northern limits of the survey area. It indicates a large long-term decline but a small rebound in recent years. The Eastern Waterfowl Survey (EWS) similarly does not distinguish between the two scaup species but primarily covers the range of Lesser Scaup; it shows little change since the survey began in 1990. Overall, there is medium confidence that the national population has experienced a moderate decrease over the long-term, although there appear to be some regional differences. Regional BBS analyses suggest that the national trend is primarily driven by a large decline in the northern Prairies and southern Northwest Territories, whereas there have been moderate to large increases from Yukon through British Columbia.

The goal for Lesser Scaup is to increase the population to the level it was at in the early 1970s, based on the Breeding Bird Survey. Trend data show that Lesser Scaup is currently below its goal range, but it has shown a stable pattern over the past decade. Analysis of recent trends and potential growth rates suggests that Lesser Scaup could reach its population goal by 2050 with the support of conservation action.