Economic influences on trapper participation and per capita harvest of muskrat

Abstract

ABSTRACTMuskrat (Ondatra zibethicus) populations in North America appear in decline in parts of their geographic range, prompting in‐depth investigations into population trends. However, long‐term data on muskrat population abundance are rare and managers often rely on harvest data to track relative changes in population sizes. These data are likely biased by factors that influence trapper participation and effort and, if left unidentified and uncontrolled for, may provide misleading indices of muskrat abundance. Using 36 years (1976–2011) of detailed muskrat‐harvest information from Illinois, USA, we estimated the relative importance of economic factors to trapper participation and annual per capita muskrat harvest. As expected, annual muskrat harvest was positively correlated with the number of individuals participating in muskrat trapping. Participation in muskrat trapping was associated positively with pelt and gas prices and negatively with the unemployment rate during the trapping season (R2 = 0.76). Variance partitioning within our most‐supported model revealed that pelt prices, independent of gasoline prices and unemployment rates, was the most important predictor of muskrat trapper participation. Our only supported model of per capita muskrat harvest indicated that gasoline prices negatively influenced the number of muskrats harvested per trapper each year (r2 = 0.17). Remaining unexplained variation in this model may be due to factors affecting muskrat availability (e.g., muskrat abundance, access to good‐quality trapping areas) to trappers and may be useful for managers investigating population trends. We recommend that future investigations using muskrat harvest data, at minimum, statistically adjust for the strong positive effect of pelt prices. © 2016 The Wildlife Society.