Arctic fox bag (Vulpes lagopus)

Arctic fox late winter in Svalbard
Photo: Stein Ø. Nilsen / Norwegian Polar Institute

The arctic fox is "critically endangered" in mainland Norway, where the Nature Diversity Act designates it as a "prioritised species", but Svalbard has a strong and sustainable population. All harvesting of species in Svalbard must take place in such a way as to maintain the natural productivity and diversity of the species and ensure that the gender, age composition and development of the populations remain essentially unchanged. This calls for knowledge about the effect of hunting on the population.

What is being monitored?

Arctic fox hunting

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The bag of arctic foxes hunted during the open season in Svalbard, which is 1 November to 15 March. The numbers refer to the end of the season. There is no clear trend in the number harvested. The harvesting number has large biannual variations. This is because harvesting numbers are based on the reproduction levels in the Arctic fox population the summer before the harvesting starts, and also on whether or not there harvesting is taking place in all the trapping areas.

Status and trend

Since the bag report has been required, the number of foxes taken annually has varied between 40 and 300, and monitoring data show no obvious long-term trend.

In the period from the 1997–98 to the 1999–2000 open seasons, people were requested not to hunt in Sassendalen and Adventdalen owing to a research project.

Considerably more foxes were taken in the 2008–2009 open season than earlier (more than 300). This was because an unusually capable and keen trapper operated from one of the trapping bases and more foxes were taken than usual; moreover, trapping had not taken place there since the 2001–2002 season.

The small bag in the 2011–2012 season also requires an explanation. This was the first season after the rabies outbreak in Svalbard in autumn 2011 and the outbreak caused the start of trapping to be delayed by a month. Moreover, that season saw a great many rain-on-snow events, and there was a large amount of ice on the tundra, making it difficult to get out to set the traps. There was no harvesting in the Bellsund trapping area this season. Low harvesting numbers every second season after the 2011-2012 season are explained by the fact that this trapping area has been given a rest.

Causal factors

The difference in the status of arctic foxes on the mainland and in Svalbard is because they live in quite different ecosystems.

The mainland has the lemming ecotype of arctic fox, and these foxes mostly feed on rodents.

Svalbard has the coastal ecotype and the diet of these foxes is dominated by items from the marine food web like seabirds and marine mammals, but also geese, ptarmigan and reindeer carcasses. The arctic foxes in Svalbard have more stable access to food and no competitors, unlike arctic foxes on the mainland, which compete with red foxes.  

Consequences

The harvesting pressure on arctic foxes in Svalbard is locally high. Even so, harvesting so far does not seem to be influencing the size of the population in Svalbard. A study paid for by the Svalbard Environmental Protection Fund has investigated how trapping affects the arctic fox population in Svalbard.

Hunting was resumed in an area (Austfjordnes) where it had not taken place for a while. This provided an opportunity to investigate the demography and genetic structure of a natural arctic fox population and one that had been exposed to hunting (i.e. before and after the hunting).

Hunting influenced the age and gender compositions (demography) in the population. Overall, the proportion of young foxes rose after the hunting, but the most important and most serious effect was that the proportion of older females (those that reproduce) was significantly reduced in a hunted population compared with a non-hunted population. This may have negative consequences for the growth potential in the population because female arctic foxes in Svalbard do not begin to reproduce before they are more than 3 or 4 years old instead of immediately after they can become sexually mature, i.e. when they are 10 months old.

Genetic analyses in this study also showed that it is mainly young males which immigrate into areas where trapping is taking place and thus help to re-establish the population.

About the monitoring

All harvesting of species in Svalbard must take place in such a way as to maintain the level of the populations and ensure that the natural gender and age composition of the species remains unchanged. This requires a small bag.

On the mainland, the arctic fox is critically endangered and the population is declining, whereas the Svalbard population is stable and strong.

Svalbard arctic foxes have a special ecological adaptation, feeding in both the terrestrial and marine ecosystems. They are at risk of contracting rabies and being infested by parasites. The management authorities have substantial responsibility for the Svalbard population, which is also of great scientific interest.

In Svalbard, there is considerable interest for harvesting arctic foxes.

In view of the current rapid changes in the climate and the consequent unknown future effects of this on the arctic ecosystems, it is important that the arctic fox population in Svalbard is carefully monitored. This is because changes in the climate may alter the availability of prey from both the terrestrial and the marine food chains, and less sea ice will hinder the immigration of foxes from other arctic continents.

Places and areas

Spitsbergen. All the areas where hunting is permitted are subject to the obligation to report bags.

Relations to other monitoring

Monitoring programme
International environmental agreements
Voluntary international cooperation
Related monitoring