The story of the Point Lay walrus haulout continues to provoke a great deal of interest. Today the reins have been taken up by Climate Progress, who have got hold of walrus expert Tony Fischbach, who wants us all to know that what we are seeing is new:
Under historical conditions, there has always been sea ice over the Chukchi Sea over the summer...This is a real change that we see thousands and tens of thousands of animals coming to shore and resting together in these large haul-outs.
This is a pretty interesting statement. I had a look at Cryosphere Today's animation of historic Arctic sea ice and as far as I can see there is rarely any sea ice over the Chukchi Sea in the summer. Take a look and see what you think. Chuckchi is pretty much at twelve o'clock, where the North American and Asian continents almost touch. In passing, we might observe that Dr Fischbach seems to be in the media most years discussing walrus haulouts and their alleged link to sea ice. Here he is discussing the 2010 haulout at Point Lay. This might colour some readers' views of him, but we should observe also that this doesn't make him wrong. Indeed he might just be concerned.
Regardless of the truth here, I'm struck by Susan Crockford's observation that in fact there are records of mass haulouts on land at St Lawrence Island, to the south of the Bering Strait and far from the sea ice. There are also records of mass haulouts on land at Wrangel Island when sea ice was close. Interestingly, the latter events are mentioned in a paper by Jay et al 2012, the author team of which included Dr Fischbach.
In years when the ice edge retreated far to the north, walruses in the western Chukchi Sea often hauled out in large numbers on Wrangel Island.
I'm finding this statement hard to square with the opinion he offered to Climate Progress about summer sea ice in the Chukchi Sea.
The connection between sea ice and walrus haulouts thus seems far from clear. One assumes that to make this case, one would want to find a correlation of some kind between haulout population and distance to the sea ice.
Dr Fischbach's paper doesn't particularly help here - it is mainly about the range of the Pacific walrus rather than haulouts per se, but haulouts are mentioned:
...in September and October in 3 (2009, 2010, and 2011) of our 4 study years, walruses foraged in nearshore areas, in contrast to foraging in offshore areas in the past, because in recent years, sea ice disappeared over the continental shelf and caused young and adult female walruses to haul-out on shore in large numbers, a condition that did not commonly occur in the past (Fay et al. 1984).
...and...
With increasing sea ice loss, it is likely that young and adult female walruses will occupy the Chukchi Sea for longer periods during the year and increase their use of coastal haul-outs and associated nearshore foraging areas (Jay et al. 2011).
I have struggled to find any support in Fay et al for the statement made in the first quote (if you review the PDF, start at p231), although it is not entirely clear what claim the citation is supporting. I'm guessing it's the claim that in the past walruses foraged offshore rather than nearshore areas - in the 1980s concerns over sea ice retreat were presumably few and far between.
However, Fay certainly discusses walruses being in nearshore areas, so this would seem to contradict my supposition. There is certainly no mention in Fay of large shore haulouts, but the paper only occasionally mentions haulout size at all. The citation therefore seems to be spurious, but it's a long paper and I may have missed something.
Interestingly, we do learn from Fay that haulout sites fall in and out of use with the walrus population, sometimes for decades at a time. And what I found particularly intruiging was this map of walrus sightings, to which I have added an arrow showing Point Lay:
There are similar maps for each month of the year and together this set of maps seems to show that there are very large populations of walrus at Point Lay from July to September.
This then leaves us with the question of whether the haulouts are land haulouts or whether the walrus are residing on the sea ice. Here's the sea ice for September 1982, a time when ice extent was much larger than today. As far as I can see, the sea ice is far, far from Point Lay.
Thus I assume that the haulouts at Point Lay that were observed in the past are likely to have been on land rather than on the sea ice.
I'm thus coming to the conclusion that my original supposition was correct. This story is ecodrivel. We know that large haulouts take place in the Bering and Chukchi seas. We know that walruses have always visited Point Lay and that the sea ice at the time is far enough away that they haulouts must have been on the land.
To be fair, the reason walruses visit this part of the world appears to be something of a mystery:
Areas of concentrated walrus foraging generally corresponded to regions of high benthic biomass...A notable exception was the occurrence of concentrated foraging in the nearshore area of northwestern Alaska. This area has low macroinfaunal biomass, a sandy substrate, and is dominated by the sand dollar Echinarachnius parma (Feder et al. 1994), which is not a typical prey item of walruses (Sheffield & Grebmeier 2009). Walruses used this area in June during their northward migration in all study years, then again in late August and September during the period from 2009 to 2011, when sea ice completely disappeared over the continental shelf in the eastern Chukchi Sea. The reasons walruses selected this apparently depauperate area for use in August and September are unclear, and it seems unlikely that the area would adequately support the foraging demands of the large aggregations of walruses that occupied the area.
However, the fact that we don't know why walruses visit the area does not mean that it is reasonable to claim that they do so because of global warming
Bishop Hill