Assessment of the Sustainability of Wolverine Harvest in British Columbia, Canada

Abstract

Wolverines (Gulo gulo) are distributed across much of northern and western Canada and Alaska, USA, and they extend south into the mountainous western United States. Wolverines occur in most regions of British Columbia, Canada, with the highest population densities occurring in the interior mountainous areas. Wolverine populations in British Columbia have been primarily managed to provide a sustainable harvest for trappers and hunters. We used spatially based population estimates, population vital rate data, and spatially based harvest data to evaluate the sustainability of wolverine harvest (trapping and hunting) from 1985 to 2004. The median annual provincial wolverine harvest from 1985 to 2004 was 172 wolverines per year (x ¼ 174.8), which was less than the median simulated estimate of provincial recruitment (195.9 wolverines/yr; x ¼ 209.7). Harvests in individual population units ranged from 0 to 280 over the 20-year period. Spatially, wolverine harvest was likely to have been unsustainable in 15 of the 71 population units with wolverines, and it was likely to have been sustainable in the remaining population units. Harvest in 5 of the other 56 population units was marginally sustainable and thus of potential management concern. To improve harvest management of wolverines in British Columbia, wildlife managers should focus on improved data collection and monitoring at a provincial scale, and they should work with trappers and hunters at regional scales to address issues specific to individual population units. Further research is required to improve the reliability of wolverine vital rate and population data.

Estimating Sustainable Harvest in Wolverine Populations Using Logistic Regression

“…Furthermore, the effect of harvest seems to be influenced by harvest sex ratios, with a stronger effect of harvest on population persistence if the proportion of harvested females was high. However, because wolverine harvest generally seems to be male-biased, sex ratios may not be a concern in most harvested populations (Lofroth and Ott 2007). Nonetheless, we suggest that sex ratio of harvested animals be routinely monitored and possibly controlled if harvest sex ratio approaches 50% females, for instance by a system with separate female quota restrictions (e.g., Swenson et al 1994).…”

“…Prior to obtaining knowledge about dispersal patterns and what ecological factors drive them, harvest in fragmented populations such as the populations in Idaho and Montana, USA (e.g., Cegelski et al 2006, Squires et al 2007) must be conservative. For northern Canada and Alaska, on the other hand, migration is not likely to be limited due to large areas of undeveloped land and high connectivity (Chappell et al 2004, Dalerum et al 2007, and harvest is likely sustainable on a regional level (Lofroth and Ott 2007). Even so, if dispersal rates are naturally low, high harvest could have substantial demographic effects locally.…”

“…The wolverine is also the least known species among the large boreal carnivores (Weaver et al 1996, Landa et al 2000). This lack of information stands in unfortunate contrast to an increased need to evaluate the effects of human impacts such as landscape fragmentation (Cegelski et al 2003, Rowland et al 2003 or human persecution or harvest (Landa et al 2000, Saether et al 2005, Golden et al 2007a, Lofroth and Ott 2007 on persistence of wolverine populations. Despite this lack of information, substantial harvest of wolverines occurs in Montana and Alaska, USA, and western Canada (Golden et al 2007a, Lofroth and Ott 2007, Squires et al 2007.…”

Wolverine behavior varies spatially with anthropogenic footprint: implications for conservation and inferences about declines

“…Hunting and trapping (Krebs et al. ; Lofroth and Ott ) may play a role, and emerging evidence suggests other carnivore competitors may also have an effect (Mattisson et al. ; Heim ).…”

“…In this event, climate change may have led to population declines (Brodie and Post 2009) and may continue to do so. Hunting and trapping (Krebs et al 2004;Lofroth and Ott 2007) may play a role, and emerging evidence suggests other carnivore competitors may also have an effect (Mattisson et al 2011;Heim 2015). However, the proximate cause(s) of wolverines' range contraction remain in question.…”