BOW VALLEY – Researchers are calling for wolverine deaths from trapping to be cut in half throughout southern Alberta and B.C..
A new study on the sustainability of wolverine trapping, published recently in the Journal of Wildlife Management, found that current trapping rates are likely unsustainable, particularly given the population is already vulnerable and there are fewer wolverines than previously thought.
The authors of the study called for annual trapping mortality to be reduced from 8.4 per cent to four per cent.
“If we continue to take eight per cent every year, then we can probably just stay where we are,” said Mirjam Barrueto, a researcher at the University of Calgary’s biological sciences department and one of nine co-authors of the study. “But if anything negative happens … that’s why the four per cent is recommended to allow for a little bit of a buffer and to allow for some wolverine recovery to happen.”
Wolverine density averaged two wolverines per 1,000 square kilometres throughout the 50,000- square-kilometre study area, covering the Kootenay-Boundary Region in southwest B.C. and the southern Rocky Mountains and foothills of southwest Alberta.
Barrueto said researchers were surprised to find such low wolverine numbers, especially in the southern Rockies.
“It’s dozens, not hundreds,” she said. “We never thought the harvest would be unsustainable until we did this study.”
About 15 trappers catch wolverines in the study area each year.
In Alberta and B.C., licensed trappers must own a registered trapline, or have permission to trap on private land or someone else’s trapline.
Wolverines can be trapped between Nov. 1-Jan. 31 in southeast B.C. and southwest Alberta. Each trapper can catch one wolverine per year in Alberta, but there is no limit in B.C.
Alberta Environment and Parks denied an interview request from the Outlook, but provided an emailed statement. Officials with the B.C. government did not get back to the Outlook by publication deadlines.
Officials say the five-year average for trapping wolverine in Alberta was 67 animals, with the harvest almost entirely taking place in northern Alberta north of Peace River.
They say the five-year average harvest of 2.3 animals annually in the study area equates to about four per cent of the population numbers that the authors cited.
“This harvest rate is deemed sustainable and there is no intent to further restrict wolverine harvest in Alberta,” said Josh Zarobiak, acting assistant director of communications and engagement with Alberta Environment and Parks.
“It is our understanding that the authors’ conclusion about wolverine harvest in south-western Alberta not being sustainable is not supported by their data,” he added.
“This is due to the fact that the report combines Alberta’s harvest, which is low, with B.C.’s relatively high harvest rates to conclude that both B.C. and Alberta harvest is not sustainable.”
Dealing with shrinking wilderness, wolverines are having a tough time moving from protected areas of Banff, Yoho and Kootenay national parks down into the United States, where wolverines are on the verge of being listed as threatened.
Wolverines naturally occur in low numbers, have low reproductive rates and need vast interconnected blocks of wilderness to survive. Their struggles are made even tougher because they are sensitive to human pressures.
Yellowstone to Yukon (Y2Y) Conservation Initiative welcomed the research, but cautioned that reducing the trapping harvest is not the silver bullet to help wolverines; just one of many human-caused threats facing the species.
Aerin Jacob, conservation specialist for Y2Y, said habitat loss from human development and disturbance from outdoor recreation can indirectly affect wolverine populations, for example, making it harder for them or their prey to live, move, and reproduce in these areas.
“We know in many cases where the most important habitat is for wolverine and should be concentrating in those places,” she said.
“This research puts the direct mortality from trapping into the broader picture of wolverine conservation.”
Jacob said the research points to the importance of reducing threats, such as roads, facing wolverines.
“Although you can have road kill and the wolverine dies, the bigger, more insidious problem is that roads reduce connectivity,” she said.
“It means wolverines are less likely to cross the roads; it’s harder for them to find mates and to breed and that has population level impacts.”
Barrueto agreed.
“Trapping is only one part. If we don’t have enough habitat – it’s the same as the caribou – there’s not going to be wolverine,” she said.
Studies show wolverines tend to avoid roads and recreation activities – logging roads, ski touring or snowmobiles – throughout the Kootenay region and the Rockies.
“We know that all these things push wolverines away, but we don’t know to what extent and we don’t know which ones we really have to focus on,” she said.
“We know snowmobiling and ski touring can have an impact on female wolverines, but we don’t know at which level and what is too much,” she added.
“Essentially wolverines need a lot of room, good food and safety. If there’s too many people, they usually disappear and if there’s too many predators, they disappear.”
Jacob said the research shows how important protected areas are for wolverines, noting the highest concentrations of wolverines tends to be in protected areas like national parks.
“That doesn’t mean that all places need to become parks; it does mean that we have to think about what happens between those places,” said Jacob.
“It’s about improving the overall landscape so wolverines and other species can move between the places that are the most important habitat for them.”
According to the study, adult female wolverines were the least likely to be trapped. Adult males were three times more likely to be caught, juvenile females six times more likely and juvenile males 10 times more likely.
“In a population, especially of a long-lived species that’s slow to reproduce that doesn’t have very many babies – wolverines and bears – the adult females are arguably the most important members of that species,” said Jacob. “When something affects their lives, that’s when it has the biggest effect for the species as a whole.”
The Alberta Trappers Association doesn’t believe there’s a need to reduce wolverine trapping.Bill Abercrombie, the group’s president, said researchers would have a hard time convincing him that a wolverine quota of one per trapline is not sustainable, noting he finds the conclusion troubling.
“I believe that our harvest numbers have been remarkably consistent over the years and that speaks for itself,” he said.
“Alberta has had a quota of one per trapline for many years and B.C. has no quota. How can that harvest data then be lumped together and used to make judgments regarding population density or abundance in certain areas when the quota is the same for the entire province in Alberta or no quota in B.C.?”
Abercrombie said the group’s own on-the-ground research shows that wolverine populations vary extensively and are, in fact, much higher in the boreal forest.
“Population comparisons between Banff National Park and Crowsnest Pass are based on different habitat types and the fact that there is more disturbance and fragmentation outside the park, not on trapping mortality,” he said.
Abercrombie said many researchers automatically assume that disturbance by infrastructure and development is always negative.
“But animals are not cookie-cutter in their reactions to humans, a fact that trappers know very well,” he said.
Barrueto said trappers have done a pretty good job of not wiping out wolverines.
“There’s way more trappers than wolverines. If every trapper wanted to take one, we’d be done,” she said. “They haven’t done that because most trappers realize there’s not very many, so they just don’t trap them.”
Y2Y notes wolverines are a symbol of wild places.
“They are already a species at risk and nobody wants to have another endangered species crisis,” said Jacob.
“Taking action at a stage where you’re still likely to be able to make a difference is supremely important, so that we can avoid getting into crisis situations.”
