Understanding the relative contributions of different sources of mortality and survival in predator populations can improve ecosystem models and management of marine ecosystems. Within the Antarctic bottom-up processes are widely cited for explaining penguin population declines, whereas for Antarctic fur seals, top-down processes are most cited as the primary driver for declining pup production. This has led to an under emphasis of the role of bottom-up drivers for controlling fur seal production within the system. We review the historical data in Antarctic pup production and provide annual pup production estimates from 2002-2012 for Cape Shirreff, Livingston Island. Age-specific natality rates are provided as an indicator of bottom-up drivers and we contrast these with early season neonate mortality and leopard seal predation rates. Fur seal pup production has undergone a dramatic declines in the last decade (12.1% per annum since 2002). Since 1998, natality rate has also declined 14%, largely driven by poor recruitment and an aging population. However, age-specific natality rate has also declined. Predation rate has increased 4% per year since 2002. We discuss the relative roles of bottom-up and top-down contributions to the decline in fur seals.
Mr Doug Cooper (CCAMLR Secretariat)