Population monitoring of arctic foxes (Vulpes lagopus)
Long term monitoring and assessment program for the arctic fox in order to detect early population changes and long term trends.
Rationale: The Norwegian Polar Institute (NPI) is through our allocation letter responsible for the long term monitoring of the arctic fox population on Svalbard. The arctic fox is listed as an indicator species for monitoring of terrestrial biodiversity in Svalbard (MOSJ).
The arctic fox is monitored because
1) they are top predators that have significant impacts on both terrestrial and marine ecosystems,
2) they are hunted annually and
3) they are important vectors for zoonosis (rabies and parasites as Echinococcus multilocularis)
Background: Data are collected from the annual monitoring of breeding arctic fox dens in two main areas, and from the annual trapping through autopsy of carcasses (demography, trapping statistics, zoonosis). The den surveys are carried out annually in two areas one in Kongsfjorden-Brøggerhalvøya and the other in Adventdalen-Sassendalen. The survey in Kongsfjorden-Brøggerhalvøya started in 1990 and covers an area of 221 km². The den survey in Adventdalen-Sassendalen started in 1982 and ended in 1989, but was started again in 1997 and is now conducted annually and covers an area of 900 km². The field work in Sassen-Adventdalen are conducted during three weeks in July, and in Kongsfjorden-Brøggerhalvøya for 8 days in July.
Data from harvesting is collected as part of the monitoring programme. Since 1996, NPI has collected and autopsied carcasses of arctic foxes that have been trapped during winter (foxes are trapped between November 15 and March 1 and between 80 and 160 foxes are trapped each year). NPI started the autopsies of these animals in 2002. Samples are stored frozen at NPI. Records to date for annual trapping of the arctic fox are posted on MOSJ web-site. Data on age structure, sex ratios, number of pups, diet, body condition, location of harvest and year of harvest are collected to estimate mortality rates, population structure and population dynamics.
Since 2008 it has been an increased interest for trapping foxes by the locals in Longyearbyen. That has resulted in an increase in trapping areas and an increase in the number of foxes trapped per year. It has also been an increase in foxes trapped at some of the trapping stations from the season 2008-2009. By combining data from den monitoring with demographic data from trapping we give advice to the Governor in Svalbard trends and possible changes in the populations.
Research and monitoring on persistent organic pollutants (POPs) in relation to feeding ecology (stable isotopes) has been carried out on samples from 1998-99. Records to date for POPs in the arctic fox are posted on MOSJ web-site. This work is conducted in cooperation with Örebro University and Norwegian Institute for Nature Research, Tromsø. Genetic studies are also ongoing, with a focus on potential fine-scale genetic structuring in the arctic fox population on the Svalbard archipelago. Samples from Svalbard are also included in a circumpolar genetic study. This work has involved international cooperation which includes among others the University of Alberta, Tel Aviv University and Stockholm University. In 2009 10 samples from arctic foxes were sent for analysis for SFT for a screening of new compounds.
Infectious diseases and parasites are also subjects of study in the monitoring programme. The arctic fox is known to be the major vector of rabies virus in the Arctic region. The arctic fox is also the determinant host of the tape worm Echinococcus multilocularis which has become established in the Grumant area in Isfjorden. This work is conducted in cooperation with the National Veterinary Institute, Tromsø, the Norwegian School of Veterinary Science, the Department of Arctic Veterinary Medicine Tromsø, University of Tromsø, the National Veterinary and Food Research Institute in Oulo, Finland and Forest Research Institute, Finland.