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Stock Status

Historical population size

The total population of Atlantic walrus prior to the European discovery of North America must have been at least in the hundreds of thousands, and was found over a much larger range than is the case today. The population number is, of course, a very rough guess, and is based on recorded observations by early explorers and traders as well as known records from commercial walrus hunting. Walrus in all areas have been exploited for centuries, first by Inuit and later by European whalers and sealers. Walrus hunting continues today to be an important part of Inuit culture in both Arctic Canada and Greenland. Walrus remains found at archaeological sites have been used to determine distribution of Atlantic walruses in Canada and Greenland in the past. In the later Paleo-eskimo period (2,500-1,000 BP) walrus remains are relatively common and occur in definite “diet-related” context (Wiig et al. 2014). Remains tend to be more common from the periods from around 2,500-2,300 BP and around 1,500-1,000 BP, than from the period in between. Paleo-eskimos appear to have abandoned the High Arctic between 2,300-1,500 BP, perhaps due to a cooling climate, which also may have affected the distribution of walruses.

Hunting by humans is considered to be the main cause of depletion of walruses during historic times (Born et al. 1995). The Norse hunted walruses in the Barents Sea and Greenland areas from sometime in the late 9th until the 15th century. Commercial hunting of walruses began in the late 1800s, roughly around the time of the end of the whaling era, and proceeded until the mid 20th century (Wiig et al. 2014). Walruses were hunted for their skins, blubber and ivory tusks. This hunt took a great toll on walrus populations, with the result that by the mid 20th century the population of Atlantic walruses had been reduced in nearly all areas and its range had shrunk substantially. At Svalbard, walruses were nearly completely extirpated (Wiig et al. 2000). Large herds which once hauled out on island and mainland beaches in cold temperate and subtemperate latitudes, for example as far south as Sable Island off Nova Scotia, Canada, have been exterminated, and walrus today are confined solely to the Arctic.

KKovack Kit0106 Old hunting

Greenland

Great uncertainty exists about the numbers taken by European whalers and sealers for all three walrus stocks in Greenland, as harvests were not well documented. Previous to the 19th century, walruses were caught by the Greenlanders, the Norse from 985 until the latter half of 15th century, and European whalers and sealers from 17th century (Wiig et al. 2014 and references therein).

Until about 1910, Scottish whalers caught walruses in the Baffin Bay region including in West Greenland and the North Water areas. Norwegian sealers and whalers took walruses between about 1910 and 1923 offshore in West Greenland, and made large catches around the 1950s, presumably in northern Baffin Bay (Witting and Born 2005).

Hudson Bay/Davis Strait

This stock, which is shared by Canada and Greenland, likelyn declined greatly between 1930 and 1960. Catches in Greenland peaked in 1938 with more than 600 animals taken, and more than 9,400 animals were taken in total over those three decades (Witting and Born 2013). The result was that the number of walruses in Central West Greenland was reduced by about 80% between 1900 and 1960. Catches were relatively low after this, and the population increased to 3,100 (95% CI: 2,500-4,400) by 1993 (Witting and Born 2013). Catches again increased, and the population experienced a minor decline between 1994 and the early 2000s.

In central Greenland, joint research on walrus between the Canadian Department of Fisheries and Oceans and the Greenland Institute of Natural Resources was begun in 2005. Aerial surveys conducted off West Greenland in the spring of 2006, 2008 and 2012 produced population estimates of 1,105 (95% CI 610–2002) in 2006, 1,137 (95% CI 468–2758) in 2008 and 1,408 (95% CI 922–2150) in 2012 (Heide-Jørgensen et al. 2013).

Aerial and boat surveys of walruses from this stock that summer in the Hoare Bay area on southeast Baffin Island were carried out in 2006 and 2007. The estimate from those surveys was 2,533 (CV=0.17) (DFO 2013a, Stewart et al. 2013b), suggesting that not all the walrus accounted for in the Canadian surveys were available for the Greenland surveys (Stewart and Hamilton 2013). None of these surveys covered the entire range of the stock, so they should be considered underestimates. Based on population modelling, the population estimate for this stock for 2012 is about 3,900 (95% CI: 2,500–5,300) individuals (Witting and Born 2013).

Concerns about overexploitation led to quotas being introduced for the stock in 2007, to cover a three year period (Andersen et al. 2013, NAMMCO 2013). The approved quotas were designed to allow for a gradual reduction of catches to ensure that removals will be within the sustainable levels recommended by the Greenland Institute of Natural Resources. Annual catches were cut from 190 to the current quota of 61 animals for West Greenland hunters and 16 for southeast Baffin Island hunters (DFO 2013a).

Baffin Bay

The North Water-Baffin Bay stock was also subject to intense hunting during the late 19th and early 20th century, and by 2005 was estimated to have declined to a population of less than 10% of the 1900 level (Witting and Born 2005). As in other areas, the decrease caused by historical catches is unclear due to incomplete catch reporting prior to the 1950s. It is estimated that the population declined by 40% from the 1960s to 2005. Quotas were introduced for this stock in 2007, and a total of 64 walruses can be harvested from the Baffin Bay stock (Wiig et al. 2014). The decline in harvest has likely led to an increase in the population.

The Baffin Bay stock of walrus was surveyed in May of 2009 and 2010, as part of a larger survey of the North Water polyna. Smith Sound and southern Kane Basin were surveyed from the air both years, resulting in a combined estimate for 2009/10 of 1499 (95% CI 1077–2087) (Heide-Jørgensen et al. 2012). A similar result was obtained by the Canadian Department of Fisheries and Oceans, which estimated the Baffin Bay stock at approximately 1,250 walruses, based on a count of 571 in 2009 (DFO 2013a). Based on population modelling, the 2012 abundance estimate is 1,400 (95% CI: 1,000–2,000) individuals, and the annual natural growth rate of this population is estimated at 7.7% (95% CI: 6.7–8.9%) (Witting and Born 2013).

East Greenland

The East Greenland population was also heavily exploited late in the 19th century and during the first half of the 20th century. As in other areas, catches were not well documented, but at least 268 walruses were taken in 1889, and at least 573 walruses were taken between 1898 and 1908. Since that time harvests of this stock have been low, except for the period from 1925 to 1939 where a total of approximately 350 walruses were taken (Witting and Born 2013).

Based on an abundance estimate from 2009, population modelling suggests these takes caused only small changes in the population, with a maximum depletion to 80% of the estimated original population in 1890 (Witting and Born 2013). Some management measures were introduced fairly early on for the protection of this stock. In 1938 and 1939 some restrictions for the hunting of walruses for Danish hunters and trappers, but not Norwegians, operating in North East Greenland north of about 73° 30' N were introduced by the Danish hunting company “Nanok”. In 1951, a decree from the Danish Ministry of State Affairs gave complete protection to walruses north of 74° 24’ N in North East Greenland (Wiig et al. 2014). Quotas were introduced for this stock in 2007, and currently allow 18 walrus to be harvested per year. The population has been increasing slowly and is now considered to be recovered with a current growth rate of 1.5% (95% CI: 0.5–3.9%) and a population estimate of 1,000 in 2005 and 1,430 (cv 0.45) in 2009 (Witting and Born 2013, NAMMCO 2013).

Canada

While walrus have been harvested by Inuit in the Canadian Arctic for centuries, it was only with the advent of commercial whaling in the late 1800s that walrus started to be heavily exploited in the high Arctic. Walrus further south, in the Gulf of St. Lawrence, were hunted to extirpation in the 1700s. Very high numbers of walrus were taken further north in the late 1890s and early 1900s, as many as 1,400 in one year. Between 1885 and 1913, whalers harvested at least 4,000 walrus from Baffin Bay–Davis Strait. In northern Hudson Bay and the Cumberland Sound area between 1831 and 1914 at least 4,750 walrus were taken (DFO 2013b). This unrestricted commercial harvesting led to a serious decline in numbers for these stocks. The other result was a restriction of walrus distribution to more northerly areas, whereas previously walrus were found as far south as the Gulf of St. Lawrence and Sable Island off Nova Scotia (Wiig et al. 2014). In 1928, regulations were introduced under the Fisheries Act banning the commercial harvesting of walrus and limiting the harvest to Inuit (DFO 2013b).

It is difficult to say to what extent walrus populations have recovered since that time or what the population trends are, as there is little data available. As mentioned above, walrus are one of the most difficult animals to survey, and even the current population estimates carry a great deal of uncertainty.

Fairly recent surveys have been carried out on all walrus stocks in Canada, with the exception of the South and East Hudson Bay stock, and these are summarized in the table above. The two Foxe Basin stocks are by far the largest and together may number over 10,000 animals. The Baffin Bay stock is shared with Greenland, and population modelling indicates the 2012 abundance estimate to be 1,400 (95% CI: 1,000–2,000) individuals, and the annual natural growth rate of this population is estimated at 7.7% (95% CI: 6.7–8.9%) (Witting and Born 2013). Similarly the Hudson Bay–Davis Strait stock is shared between Canada and Greenland. Only a small portion of the Hudson Bay–Davis Strait stock range has been surveyed so existing estimates are almost certainly negatively biased. Population modelling suggests a 2012 stock size of 3,900 (95% CI: 2,500-5,300) individuals (Witting and Born 2013). Further investigations into the movement patterns between Canada and Greenland are required for this stock.

No stock identification information or recent estimates of population size are available for the South and East Hudson Bay stock.

Norway

It is difficult to estimate the size of the original population prior to hunting, but the Svalbard/Franz Josef Land population must have once been very large. The first recorded hunt of Atlantic walrus occurred in Svalbard in 1604 (Wiig et al. 2014), after which hunting continued for the next 200 years. By the middle of the 19th century the stock showed clear signs of decrease. The centuries of walrus hunting had brought the large herds in Svalbard to the verge of extinction. Because of this, all hunting was banned and walrus were given total protection in 1952 (Wiig et al. 2014).

Since that time, the population has been increasing slowly. A survey of all known terrestrial haul-out sites in Svalbard was carried out during August 2006. Overall, 2629 (95% CI: 2318–2998) walruses were estimated to be present in the Svalbard area during that period. Since the walruses in this area are predominantly males and make up only part of a common Svalbard–Franz Josef Land population, it is assumed that this population as a whole numbers more than 5000 animals (Lydersen et al. 2008). A more recent survey of Svalbard was completed in 2012. The results are not yet complete, however an increase in both total numbers and females with calves compared with the 2006 survey is apparent (NAMMCO 2013). In the north-eastern corner of the archipelago females and calves have been regularly observed in increasing numbers in recent years (Lydersen and Kovacs 2013).

Russia

The pre-harvest walrus population in the Barents Sea (Svalbard-Franz Josef Land) population was probably more than 30,000 but is only around 5,000 animals today (Lydersen et al. 2008). Walrus hunting in Franz Josef Land first became a significant mortality factor around 1900 (Gjertz et al. 1992). From then until the late 1920s Norwegian sealers harvested a considerable number of walruses at Franz Josef Land. The total registered catch for the period 1880 to 1950 was estimated to be about 5,900 animals (Gjertz et al. 1992). The original population size of walruses in Franz Josef Land in 1897 was estimated to be from 6,000 to 12,000 walruses (Wiig et al. 2014 and references therein). Walrus have been protected in the western Russian Arctic since 1956, and there has been no hunting of them in Russia since that time (Wiig et al. 2014).

In terms of current population levels or trends for the stock, little data is available for walruses along the Russian coast. The first investigation of walrus numbers in the Pechora Sea was carried out in 2011, through an aerial survey of 2,563 km of coastline which used a combination of infrared sensing and digital imagery. Hauled-out walruses were found at three sites: one on Vaygach Island and two on Matveyev Island. A total of 968 animals were counted on aerial photographs, all of which appeared to be males (Lydersen et al. 2012). Using an adjustment factor developed for male walruses in Svalbard to account for animals at sea during the survey, the number of walruses occupying this area was estimated to be 3,943 (95 % CI, 3,605–4,325). No females with calves were seen in this survey (Lydersen et al. 2012).

 

References