Evaluating threats to South Shetland Antarctic fur seals amidst population collapse

Abstract

Antarctic fur seals (Arctocephalus gazella) are an iconic marine mammal, an important component of Antarctic ecosystems, and a key indicator species for regional fisheries management. Recent studies have demonstrated Arctocephalus gazella is composed of at least four distinct subpopulations, including one breeding on the South Shetland Islands. These South Shetland Antarctic fur seals (SSAFS) are the highest latitude population of otariids in the world. As such, this subpopulation faces a unique array of environmental and ecological challenges, harbours a disproportionately large reservoir of genetic diversity for the species, and has experienced catastrophic population decline in the last 15 years (2008–2023). We review the array of current and potential threats to the successful recovery of SSAFS. If decision makers wish to promote resilience and support a robust population of this species with future recovery potential, actions are needed to address threats ranging from uncertain to critical, including debris entanglement, climate change, incidental mortality, and resource competition with the krill fishery. In particular, the risks associated with overlap in the spatial and temporal distribution of the young of the year and the krill fishery should be addressed carefully. There is an urgent need for updated population estimates for all Antarctic fur seal subpopulations, analysis on the population viability of the SSAFS, and further characterising summer and winter foraging behaviours to better inform potential conservation actions.

Future climate‐induced distribution shifts in a sexually dimorphic key predator of the Southern Ocean

“…Global warming was initially predicted to have a neutral effect on Antarctic fur seal populations (Siniff et al, 2008), but there is increasing evidence of population declines both in colonies breeding close to the Antarctic Convergence (Forcada et al, 2023;Forcada & Hoffman, 2014) and in the South Shetland Islands (Krause et al, 2022(Krause et al, , 2023Schwarz et al, 2013). It is worth noting that the three subpopulations in the Atlantic Sector of the Southern Ocean (South Georgia Islands, South Shetland Islands and Bouvet Island) are demographically independent (Krause et al, 2023) and that the reasons for their decline are also different, although at least partially related to global warming (Forcada et al, 2023;Krause et al, 2022Krause et al, , 2023. For all these reasons, the species constitutes an excellent model to test whether males and females will respond differently to global warming.…”