Assessing indicators of harvest sustainability in northern populations of marten (Martes americana).

American martens (Martes americana) are often targeted by fur trappers across their distributional range; yet, there are few studies to assess the sustainability of harvest. In the absence of reliable information on abundance, data on the demographics of the harvested segment of populations can be used to provide insights on harvest sustainability. In response to concerns by some fur trappers that marten abundance was low in some areas, we collected 2,394 marten carcasses from three regions of Yukon, Canada, to investigate demographic trends in harvested martens among and within eight trapping seasons (1 November to 28 February; 2002/2003 to 2009/2010). We found consistently higher proportions of females in the harvest (42%) than recommended thresholds or previously reported for other localities. Juveniles made up approximately half of the overall harvest, and the proportion of juveniles varied significantly among trapping seasons (range = 2–90%). During trapping seasons with < 50% juveniles in the harvest, demographic harvest indicators showed signs of unsustainable harvest beginning in December. We also observed higher daily harvest rates (i.e., total number of animals harvested) in early winter and lowest harvest rates in February. Our results suggest that martens in a quota-free system were periodically vulnerable to local over-harvest. Much of the Yukon is remote with likely little trapping pressure, effectively providing harvest refugia for martens and allowing for continual over-harvest in areas with significant trapping pressure. As such, identifying and maintaining putative harvest refugia will be key to ensuring marten harvest is sustainable at broader temporal and spatial scales, especially in the absence of annually adjusted quotas. Regardless, ensuring sustainable harvest of this small carnivore in the future will require improvements to monitoring marten and the availability of their cyclic prey, continued stewardship by trappers, and possibly establishing quotas in areas of concern. Mandatory harvest reporting can aid in evaluating harvest sustainability at broad temporal and spatial scales. [ABSTRACT FROM AUTHOR]