Conservation needs for the endangered New Zealand sea lion, <scp><i>Phocarctos hookeri</i></scp>

Abstract

Abstract Understanding population size and trend is critical information in species management and conservation. To enable accurate population trend estimates, consistent robust monitoring of a species is essential, particularly for a species such as the New Zealand (NZ) sea lion, Phocarctos hookeri , which has experienced an almost continuous decline in pup production since the late 1990s. This research examines the pup production estimates for all known breeding sites for this species, and using a stage‐structured matrix population model, estimates population size and trend between 1995 and 2015. Overall, it is estimated that 2,316 pups were born in 2015, a decrease of 13% since 1995 and a 27% decline since the highest pup production estimate in 1998. This decline has been driven by the significant decline of 48% at the main breeding area, the Auckland Islands since 1998. Using the stage‐structured matrix population model a total species population size of 11,767 sea lions (95% CrI: 10,790–12,923) was estimated. This is the lowest population size of any sea lion species. Trend data for the Auckland Islands indicated that pup and population numbers have decreased at 1.9% yr −1 in the last 20 yr, while total species population decline is 0.6% yr −1 . Estimates of population trends for this species have been hindered by inconsistent monitoring at most breeding sites. This study strengthens the growing field of research highlighting the need for consistent long‐term monitoring for the conservation management of endangered species.