Phogue crabier

Crabeater Seals are thought to be the most abundant seal species globally and are among the most numerous large mammals on Earth.
Mass mortality events involving Crabeater Seals have been reported periodically. For example, in 1955, approximately 3,000 individuals died near a research station on the Antarctic Peninsula after becoming trapped 5-25 km from open water. The mortality occurred over a two- to three-month period. Post-mortem examinations revealed that seals were not emaciated; numerous foetal abortions were observed. A disease outbreak was suspected, but not confirmed. In the 1980s, antibodies to canine distemper virus (CDV) were detected in Crabeater Seals from this region (Bengtson and Boveng 1991).
More recently, a potential Unusual Mortality Event (UME) was documented in November 2024, involving 37 adult and subadult Crabeater Seals found within 500 m of each other (Jessica Farrer, pers. comm.). The carcasses appeared to have been deceased for some time, as they were frozen, partially snow-covered, and showed signs of some scavenger activity. Starvation was considered unlikely, as the seals were in good body condition. However, the cause of death was not determined because the carcasses were not sampled or examined. This UME coincided with the arrival of the Highly Pathogenic Avian Influenza (HPAI) in Sub-Antarctic islands and on the Antarctic continent, where the virus has been confirmed in several avian species. Although cases of HPAI-associated mortality have been reported in Southern Elephant Seals (Mirounga leonina) and Antarctic Fur Seals (Arctocephalus gazella), and walruses (Odobenus rosmarus), there is limited monitoring of ice-associated seals. Consequently, the presence of HPAI in Crabeater Seals cannot currently be confirmed or ruled out.
Several short-lived episodes of commercial harvesting of Crabeater Seals were ultimately discontinued due to a lack of economic viability. While there are currently no direct anthropogenic threats across most of the species’ range, large-scale commercial exploitation of Antarctic krill, the primary component of the Crabeater Seal’s diet, could pose a significant threat if it becomes widespread. Although there are no reports of fisheries interactions, at least one mortality of a Crabeater Seal has been reported for the Antarctic toothfish (Dissostichus mawsoni) fishery in the Ross Sea (CCAMLR 2023).
The effects of global climate change on Antarctic seals remain largely unknown. However, Learmonth et al. (2006) suggested that Crabeater Seal populations may decline with increasing temperatures if Antarctic sea ice is significantly reduced. Loss of sufficient areas of pack ice, used for pupping, resting, predator avoidance, and access to preferred foraging grounds, could result in population decreases. 
Furthermore, Crabeater Seals’ high dietary specialisation on Antarctic krill makes them particularly vulnerable to reductions in sea ice, which is critical for the survival of juvenile krill and ultimately determines the biomass available to higher trophic-level predators. Habitat preference models based on movement and diving data project a southward shift in the distribution of Crabeater Seals, consistent with observed and predicted shifts in Antarctic krill distribution (Hückstädt et al. 2020). Such a shift could result in spatial mismatches between suitable haul-out sites and foraging grounds, potentially increasing energetic costs as individuals may need to travel to greater distances to access prey.
It remains unclear whether Crabeater Seals can shift from their highly specialised, krill-based diet to a more generalist foraging strategy in response to the rapid loss of sea ice. Stable isotope analyses of individuals from the Antarctic Peninsula have shown an increased incorporation of fish in their diets during years of reduced sea ice extent (Huckstadt et al. 2012). Similarly, evidence from the 2022-2023 period indicates that the contribution of fish to the Crabeater Seal diet increased during these record-breaking low sea ice years (Anna Pearson, pers. comm.). The broader impacts of large-scale sea ice loss on the Antarctic continent, ongoing climate warming, and sea-level rise – particularly regarding changes to ocean circulation, ecosystem productivity and the implications for Antarctic marine predators such as seals – remain poorly understood.
Seasonal tourism in the Antarctic and Sub-Antarctic regions has increased steadily over the past three decades and bounced back quickly after the COVID-19 pandemic, to reach record numbers during the last austral summer season (Convey 2024). However, the potential effects of increased vessel noise, disturbance from ship traffic, and close human approach, either via small boat or land-based excursions, on the behaviour, distribution, foraging activity, and health of Crabeater Seals remain poorly understood. Additionally, there is a minor but non-negligible risk of physical harm to seals from vessel collisions or crushing injuries due to the passage of large ships through sea ice.

The Crabeater Seal is not listed as endangered or threatened. They are protected from hunting by the Antarctic Treaty and the Convention for the Conservation of Antarctic Seals, and any future commercial harvest would have to be regulated through those international agreements (Reijnders et al. 1993).