The Canadian population of Long-tailed Duck is best monitored by the Christmas Bird Count (CBC), which samples a moderate to high proportion of the wintering range and has moderate precision. It shows a large decrease of 83% relative to 1970, with the greatest declines occurring in the 1980s and 1990s. The British Columbia Coastal Waterbird Survey (BCCWS) also samples the portion of the population that winters along the southern British Columbia coast, and shows a similarly high decline of 73%, but over a shorter period, from 1999 to 2018.

The goal for Long-tailed Duck is to increase the population to the level it was at in the early 1970s, based on the Christmas Bird Count. Trend data show that Long-tailed Duck is far below its goal range although it has shown stabilization over the past decade. However, because of the severity of the population decline since the early 1970s, it is not realistic for the goal to be met by 2050. Based on analysis of the historical population loss and potential growth rates, the interim target is to reach 35% of the goal by 2050. Achieving this target, and ultimately reaching the national goal for this species, will require ambitious and long-term conservation action.