Walrus

Last updated 10 May 2019

The Svalbard walrus (Odobenus marinus) population was hunted to near extinction hundreds of years ago and remains Red Listed (Vulnerable) today. Surveys on haul-out sites show that the number of walruses in Svalbard is increasing.

Status and trend

Walruses were once extremely abundant in the Svalbard Archipelago, but 350 years of unregulated harvest brought them to the brink of extinction before they were protected in 1952. Born (1984) summarized observations of walruses in the Svalbard area from 1954–1982 and concluded that the summering stock was about 100 animals, and that there had been an increase in numbers since 1970. In 1993, a total of 741 walruses were observed in Svalbard based on maximum numbers of animals counted at various haul-out sites during fixed-wing and ground surveys performed over the period from August-October (Gjertz and Wiig 1995). It has been documented by several studies that the walruses in Svalbard are part of a larger, common Svalbard – Franz Josef Land population. Based on this fact and an assumed equal sex ratio, Gjertz and Wiig (1995) suggested that this shared population consisted of a minimum of 1450 walruses (age 2+, plus an unknown number of calves). These reports supported the general impression of a slow recovery taking place, based on increasing numbers of sightings of walruses at an increasing number of haul-out sites in Svalbard (Norwegian Polar Institute’s Fauna and Marine Mammal Sightings Databases). The sex ratio in the Svalbard area over the decades between the 1950s and 1990s was highly skewed. Most walruses repatriating the archipelago were males; females were almost entirely restricted to a few haul-out sites in the northeast corner of Nordaustlandet and accounted for only a few per cent of the population. This is in marked contrast to the 33% of the population that was comprised of females during the harvesting in the 1800s (Wiig et al. 2007).

The first systematic abundance survey for MOSJ was conducted in 2006 (Lydersen et al. 2008). This survey covered all known terrestrial haul-out sites within Svalbard (79 in total) during a tight time window (1–3 August). 17 haul-out sites were occupied by animals when the survey was flown. The photographs of the active sites revealed 657 animals. An extensive behavioural data set from satellite-relay-data-loggers was used to correct for animals that were in the water at the time of the survey. The resulting estimate was 2629 (95% CI: 2318–2998).

The second survey in this MOSJ time series was flown in 2012 (Kovacs et al. 2014), and the new estimate is 3886 (95% CI: 3553–4262). 91 haul-out sites are now registered in the Polar Institute’s terrestrial haul-out data-base, and 24 of them were occupied during the survey. 9 of the active sites contained females with calves, in contrast to 1 site in the 2006 survey.

The third survey in this time series was carried out in 2018. At the time of the survey 5503 (95% CI: 5031-6036) walrus were estimated in the Svalbard area. This is a 41.6% increase since the previous survey. Animals were present at 19 of the visited haul-out sites, and calves were observed at seven of these. In 2018 there were 98 terrestrial walrus haul-out sites in the data base for Svalbard.

Causal factors

Walruses were once extremely abundant in Svalbard, but 350 years of unregulated harvest brought them to the brink of extinction. Walruses were protected in Svalbard in 1952, at a time when there were only a hundred animals left.

After more than 60 years of protection, the population size in Svalbard is still small, and the species is still on the Red List as a threatened species. The number of walruses has been increasing in recent years, and walruses have gradually been observed on haul-out sites where they have not been observed for many decades.

The last survey from 2018 shows that the number of walruses in Svalbard is increasing.

Consequences

In common with other Arctic species that have been harvested way beyond sustainable levels, we do not know how abundant the species might be after harvest ends, as this also depends on the carrying capacity of the environment.

The walrus is less vulnerable for changes in sea ice extent than other species, but this does not mean that the population will not respond to rapid climate change.

About the monitoring

The Svalbard walrus population was hunted to near extinction hundreds of years ago and remains Red Listed (Vulnerable) today. Its distribution, abundance and response(s) to climate change, particularly sea ice, should be carefully monitored.

Further reading