Muskrat Ecology in the Mackenzie Delta: Insights from Local Knowledge and Ecological Field Surveys

Abstract

A rctic deltas have been called keystone ecosystems because of the numerous processes they influence at the land-ocean interface, such as nutrient cycling and sea ice formation (Lesack et al., 2014). Climate change is proceeding more rapidly in the Arctic than in any other region (ACIA, 2004), and low-lying Arctic deltas are expected to be significantly affected by the combined effects of changes in both terrestrial and marine environments (Walker, 1998). Terrestrial changes that are particularly concerning include increases in summer precipitation and the altered timing of spring breakup (Goulding et al., 2009; Lesack et al., 2014). Marine processes, including sea level rise, increased storm surge activity, and reduced sea ice cover will also affect Arctic deltas (ACIA, 2004; Lantz et al., 2015). The Mackenzie Delta in Canada’s western Arctic, the second largest Arctic delta in the world, is a low-lying alluvial plain that contains thousands of small lakes (Emmerton et al., 2007) (Fig. 1). The numerous water bodies in the delta offer abundant habitat for fish, birds, and mammals, including muskrats (Ondatra zibethicus). Muskrats are semiaquatic furbearers whose populations respond to water levels and may serve as an indicator species for changes in wetland ecosystems (Fuller, 1951; Weller, 1988). They are prey species for marten, mink, red fox, black bear, otter, wolves, and grizzly bears (Fuller, 1951; Jelinski, 1989) and can have significant effects on the vegetation in their habitat (Errington, 1963; Nyman et al., 1993; Smirnov and Tretyakov, 1998). Muskrats also supported a prolific fur and subsistence economy in the North throughout the 19th and 20th centuries (Stevens, 1953; Krech, 1976; Alunik et al., 2003). While participation in the fur trade has declined since the 1950s as a result of low fur prices and the high cost of trapping, muskrats remain important culturally and economically and are still used for subsistence and income (Gwich’in Elders, 1997; A. Gordon, pers. comm. 2013). Like other northern mammals, muskrats exhibit periodic cycles in population size (Errington, 1963; Krebs, 1996). It has been suggested that these cycles are caused by disease outbreaks, predator population cycles, and intrinsic and external factors (Erb et al., 2000; Krebs, 2013). Research on fur returns from the Mackenzie Delta in the late 1800s to early 1900s indicates that population cycles in the delta average around 10 years between highs (Clarke, 1944). In recent years, many residents of the Mackenzie Delta region have reported declines in muskrat abundance that are outside the normal range of variation (ABEKS, 2003, 2008). This decline is likely to have significant impacts on local communities that rely on muskrats for subsistence, trapping income, and overall wellbeing (Parlee et al., 2005; Gill et al., 2014) and may be related to changes in the climate and hydrological processes in the Mackenzie Delta. The primary objective of my research is to investigate reported declines in muskrat populations and examine linkages between habitat use and biophysical conditions in the Mackenzie Delta. The traditional knowledge held by land users, informed by the experiences of past and present generations, is a valuable resource for understanding why, when, and where changes in muskrat ecology and harvesting have taken place. In the first part of my research, I explore the insights that local knowledge holders provide regarding changes in muskrat ecology and harvesting practices in the Mackenzie Delta over the last 100 years. In the second part of my research, I use field surveys to identify and characterize biophysical conditions linked to muskrat habitat use.