Svalbard walrus thrive in the face of sea ice decline, mocking predictions of future catastrophe

From Polar Bear Science

Dr. Susan Crockford

The extended visit of an immature male walrus to the UK last month (dubbed ‘Thor’, presumably from Svalbard, Norway) has precipitated the tired and vacuous ‘victim of climate change’ cries from the peanut gallery, including Bob Ward of the Grantham Institute. The facts, however, put all that to rest.

I wrote about Ward in my book, Sir David Attenborough and the Walrus Deception, because he has a habit of tenaciously filing official complaints when anyone says or writes anything sensible that just happens to challenge the reigning narrative that climate change is ruining everything and will drive virtually every beloved species to extinction.

And as usual, Ward is wrong again, this time about Atlantic walrus, who have been busily rebuilding their once-decimated populations brought to near-extinction levels by human slaughter over 350 years. Legal protections against hunting enacted by Norway in 1952 have allowed the species to recover, albeit slowly.

That’s because in some areas (like Svalbard) very few females were left to populate the old hauling grounds (NPI 2022), which markedly reduced the rate of recovery until very recently.

Atlantic walrus status

The IUCN Red List classified the Atlantic walrus as ‘near threatened’ in 2016: an important step below ‘vulnerable’ which takes into account current healthy population numbers. This was despite concerns the subspecies could possibly face a population decline of >10% within three generations due to sea ice loss (much less than the Pacific walrus suffered due to food deprivation back in the 1980s (Fay et al. 1989; Lowry 1985), before everything could be blamed on lack of sea ice).

The US Fish and Wildlife Service determined in October 2017 that the Pacific walrus is not being harmed by climate change and is not likely to be harmed within the foreseeable future (MacCracken et al. 2017; USFWS 2017). The IUCN Red List (2015) assessed the Pacific walrus as ‘data deficient‘ (Lowry 2015). Despite these findings, the IUCN listed the walrus species (i.e. both subspecies together), as ‘vulnerable’ (Lowry 2016), apparently based on modelled projections of future declines.

In Svalbard, however, Atlantic walrus numbers have been steadily rising as summer sea ice has been falling. The Norwegian MOSJ website has conveniently graphed this trajectory, copied below:

The numbers on the graph start with two baseline estimated numbers provided in 1980 and 1993 (1980=100 and 1993=741), and conclude with population counts from aerial surveys done in 2006, 2012, and 2018 (2006=2629; 2012=3886; 2018=5503).That’s 109% between 2006 and 2018, and 42% between 2012 and 2018: impressive increases for any species.

However, the 2016 North Atlantic Marine Mammal Commission (NAMMCO) Report on Atlantic walrus (updated in 2021) stated that the tendency of animals to pile on top of each other at haulouts makes it hard to see every individual, even if you are counting them in a photograph. Large numbers of animals in the water are similarly difficult to count, especially if they are close together and actively diving and swimming.

As a consequence, officials determined that all recent counts of Atlantic walrus were probably an underestimate of the true population abundance. This means the 2018 estimate based on an aerial survey was likely an underestimate, which means it’s highly likely (given other evidence) that numbers have continued to climb since then.

Sea ice

Arctic sea ice since 1979 has declined dramatically in summer–and very modestly in winter–but from 2007 to 2019, that declining pattern stalled. That’s not my opinion but the conclusion of Walt Meier of the US National Snow and Ice Data Center (NSIDC), who showed the flat trend in a graph published in September 2019. The same pattern continues to 2022:

However, overall sea ice coverage is of little consequence to the issue of Atlantic walrus health and survival around Svalbard: what we need to know is what the ice has been doing in the Barents Sea, especially over the last 15 years or so.

Data on Barents Sea ice since 2006 has been published by Regehr et al. (2016) but only up to 2015. It shows the greatest decline of all Arctic regions: a loss of 4.11 days per year. It appears that this trend may have continued to 2022 (Frey et al. 2022).

In other words, the Svalbard population of Atlantic walrus increased 109% between 2006 and 2018, even as summer sea ice declined markedly in the Barents Sea.

[In Franz Joseph Land, in the eastern half of the Barents Sea, walrus numbers in 2017 were estimated to be approaching “pre-hunting levels” (9,000-11,000)].

As did Matt Ridley, I call that walrus thriving in the face of sea ice loss. It makes a mockery of model predictions of future calamity based on summer sea ice loss because it is now clear that the less summer sea ice, the more food for walrus and other species (see below). Winter and early spring ice, on the other hand, is declining only modestly and that’s when walrus really need it to mate and give birth.

Primary Productivity Increases

A report by Frey and colleagues this year (Frey et al. 2022) confirms that primary productivity–which generates more food for walrus–has continued to increase due to less sea ice coverage in summer since 2003, especially in the Barents Sea (Crockford 2021).

In the graphic from the report copied below, note the marked overall increase in primary productivity in the Barents Sea compared to other regions (left column, 3rd from the top): it has seen the greatest increase in primary productivity, including a huge spike in 2017 (the year before the last walrus survey).

The increased amount of food available to all species (including walrus) means that the carrying capacity of the Barents marine ecosystem has also increased since 2003–all as a consequence of dramatically less summer sea ice.

Wandering juveniles

Despite all of the above, we shouldn’t forget the individual that started this discussion: a lone male estimated to be 3-5 years of age that visited the UK in December. In other words, an immature animal a decade away from what is considered breeding age for males (about 15 years). Mature walrus congregate on the sea ice to mate and give birth in the winter/early spring (January-April); immature animals and seniors past breeding age do not participate in this activity and are free to wander well away from the pack ice (Freitas et al. 2009; NAMMCO 2021).

Wanderer ‘Thor’, as long as he stuck to shallow coastal regions where he could feed easily (as he apparently did), was not in any danger from climate change on his UK sojourn, which had the added advantage of being well out of range of predatory polar bears.

References

Crockford, S.J. 2021. The State of the Polar Bear Report 2020. Global Warming Policy Foundation Report 48, London. PDF here.

Crockford, S.J. 2022. Sir David Attenborough and the Walrus Deception. Amazon KDP.

Fay, F.H., Kelly, B.P. and Sease, J.L. 1989. Managing the exploitation of Pacific walruses: a tradegy of delayed response and poor communication. Marine Mammal Science 5:1-16. PDF HERE.

Freitas, C., Kovacs, K.M., Ims, R.A. et al. 2009. Deep into the ice: overwintering and habitat selection in Atlantic walruses. Marine Ecology Progress Series 375:247-261.

Frey, K.E., Comiso, J.C., Cooper, L.W., Garcia-Eidell, C., Grebmeier, J.M. and Stock, L.V. 2022. Arctic Ocean primiary productivity: the response of marine algae to climate warming and sea ice decline. 2022 Arctic Report Card. NOAA.DOI: 10.25923/0je1-te61

Kovacs, K.M. 2016. Odobenus rosmarus ssp. rosmarus. The IUCN Red List of Threatened
Species 2016: e.T15108A66992323. http://dx.doi.org/10.2305/IUCN.UK.2016-1.RLTS.T15108A66992323.en

Lowry, L. 1985. “Pacific Walrus – Boom or Bust?” Alaska Fish & Game Magazine July/August: 2-5. pdf here.

Lowry, L. 2015. Odobenus rosmarus ssp. divergensThe IUCN Red List of Threatened Species 2015: e.T61963499A45228901. https://dx.doi.org/10.2305/IUCN.UK.2015-4.RLTS.T61963499A45228901.en.

Lowry, L. 2016. Odobenus rosmarusThe IUCN Red List of Threatened Species 2016: e.T15106A45228501.

MacCracken, J.G., Beatty, W.S., Garlich-Miller, J.L., Kissling, M.L and Snyder, J.A. 2017. Final Species Status Assessment for the Pacific Walrus (Odobenus rosmarus divergens), May 2017 (Version 1.0). US Fish & Wildlife Service, Anchorage, AK. Pdf here (8.6 mb).

NAMMCO. 2021. Atlantic walrus. North Atlantic Marine Mammal Commission Report for 2016, updated January 2021. Tromso, Norway. https://nammco.no/topics/atlantic-walrus/

NPI (Norwegian Polar Institute). 2022. Walrus population in Svalbard. Environmental Monitoring of Svalbard and Jan Mayen (MOSJ). http://www.mosj.no/en/fauna/marine/walrus-population.html

Regehr, E.V., Laidre, K.L, Akçakaya, H.R., Amstrup, S.C., Atwood, T.C., Lunn, N.J., et al. 2016. Conservation status of polar bears (Ursus maritimus) in relation to projected sea-ice declines. Biology Letters 12: 20160556. http://rsbl.royalsocietypublishing.org/content/12/12/20160556USFWS 2017.“Endangered and Threatened Wildlife and Plants; 12-Month Findings on Petitions to List 25 Species as Endangered or Threatened Species” [pdf] 4 October 

via Watts Up With That?

https://ift.tt/CfnIae2

January 8, 2023 at 12:43PM

Leave a Reply

Fill in your details below or click an icon to log in:

WordPress.com Logo

You are commenting using your WordPress.com account. Log Out /  Change )

Twitter picture

You are commenting using your Twitter account. Log Out /  Change )

Facebook photo

You are commenting using your Facebook account. Log Out /  Change )

Connecting to %s