The State of Circumpolar Walrus Populations

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Garlich-Miller et al. (2011) assumed that summer sea ice loss would result in a walrus population
decline over time, and that subsistence harvests could become unsustainable if not reduced in
concert with any population declines. The Native Villages of Gambell and Savoonga (Alaska) have
recently adopted trip limit ordinances, and a Tribal Wildlife Grant was acquired to ensure
administration (USFWS 2014; Allen and Angliss 2015). These are positive developments for the
continued management of subsistence harvests. The USFWS, in cooperation with the Russian
Federation, has established a comprehensive monitoring program to gather detailed information
on harvest trends and characteristics (Allen and Angliss 2015). The USFWS has developed
Cooperative Agreements with the Eskimo Walrus Commission annually since 1997 to facilitate
local participation in walrus conservation and management activities in Alaska (USFWS 2014).
This co-management process is on-going.
Predation by polar bears and killer whales may also increase as walruses are forced to make
greater use of terrestrial sites and spend more time in open water (Garlich-Miller et al. 2011).
Young walruses will be most at risk from predation by these species. Walruses are consumed most
often by older male polar bears, and there is spatial variation in the importance of walruses as a
prey item (Thiemann et al. 2007, 2008; Galicia et al. 2015). Killer whales prey on Pacific walruses
(Kryukova et al. 2012) but Inuit indicate that killer whales in the eastern Canadian Arctic rarely if
ever feed on Atlantic walrus (Ferguson et al. 2012). If the availability of their other prey declines
they may learn to successfully hunt walruses.
Disease and parasite transmission could increase in response to increased terrestrial haulout use
(Burek et al. 2008; Sonsthagen 2012). Walruses might also be exposed to novel pathogens and
parasites as vector species expand their distributions northward. In September 2011, 6% of the
walruses at the Point Lay haulout had skin lesions that were similar to those observed on ringed
seals that summer and fall and suggestive of a viral infection (Garlich-Miller et al. 2011; USFWS
2014). Nearly half of the seals were dead and the rest were lethargic, but the walruses were in
good physical condition other than the lesions. Most of affected walruses were subadults and
some had healed lesions, which would indicate that the disorder is not necessarily fatal (Garlich-
Miller et al. 2011; USFWS 2014). A number of dead calves at the haulout had both skin lesions
and signs of trampling trauma however, and the ultimate cause of death is not known. In
December 2011, the National Marine Science Fisheries (NMFS) declared the seal mortalities an
unusual mortality event (UME) and with USFWS concurrence, included walrus in the UME due to
the similarities of the lesions (Garlich-Miller et al. 2011; USFWS 2014). No causative agent has
been identified and it is unknown whether or not the same agent is infecting both species
(symptoms appear to be less severe in walruses). Tissue sampling and laboratory analyses are ongoing
(Garlich-Miller et al. 2011; USFWS 2014).