Table_1_The Rapid Population Collapse of a Key Marine Predator in the Northern Antarctic Peninsula Endangers Genetic Diversity and Resilience to Clima.docx

Antarctic fur seals (AFS) are an ecologically important predator and a focal indicator species for ecosystem-based Antarctic fisheries management. This species suffered intensive anthropogenic exploitation until the early 1900s, but recolonized most of its former distribution, including the southern-most colony at Cape Shirreff, South Shetland Islands (SSI). The IUCN describes a single, global AFS population of least concern; however, extensive genetic analyses clearly identify four distinct breeding stocks, including one in the SSI. To update the population status of SSI AFS, we analyzed 20 years of field-based data including population counts, body size and condition, natality, recruitment, foraging behaviors, return rates, and pup mortality at the largest SSI colony. Our findings show a precipitous decline in AFS abundance (86% decrease since 2007), likely driven by leopard seal predation (increasing since 2001, p << 0.001) and potentially worsening summer foraging conditions. We estimated that leopard seals consumed an average of 69.3% (range: 50.3–80.9%) of all AFS pups born each year since 2010. AFS foraging-trip durations, an index of their foraging habitat quality, were consistent with decreasing krill and fish availability. Significant improvement in the age-specific over-winter body condition of AFS indicates that observed population declines are driven by processes local to the northern Antarctic Peninsula. The loss of SSI AFS would substantially reduce the genetic diversity of the species, and decrease its resilience to climate change. There is an urgent need to reevaluate the conservation status of Antarctic fur seals, particularly for the rapidly declining SSI population.

To provide empirical data documenting the rapid decline of Antarctic Fur Seals at Cape Shirreff, as well as the important genetic diversity of this population.

Supplementary Data from Krause DJ, Bonin CA, Goebel ME, Reiss CS and Watters GM (2022) The Rapid Population Collapse of a Key Marine Predator in the Northern Antarctic Peninsula Endangers Genetic Diversity and Resilience to Climate Change. Front. Mar. Sci. 8:796488. doi: 10.3389/fmars.2021.796488

Krause DJ, Bonin CA, Goebel ME, Reiss CS and Watters GM (2022) The Rapid Population Collapse of a Key Marine Predator in the Northern Antarctic Peninsula Endangers Genetic Diversity and Resilience to Climate Change. Front. Mar. Sci. 8:796488. doi: 10.3389/fmars.2021.796488

Table S1. Total synoptic pup counts (live and dead) from the South Shetland Archipelago (SSI), and from the subset breeding colonies at Cape Shirreff (CS, reported with standard deviation (±SD) where available) and the San Telmo Islets (STI) during the 1959 – 2020 austral summers. All summers are referred to by the year the season ended. Data collected by the U.S. AMLR Program (this study) unless otherwise indicated.

FAO Area 48.1, CCAMLR Area 48.1, Antarctic Peninsula, South Shetland Islands, South Orkney Islands

Available online at https://www.frontiersin.org/articles/10.3389/fmars.2021.796488/full#supplementary-material

https://www.frontiersin.org/articles/10.3389/fmars.2021.796488/full#supplementary-material

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