Increasing pup production of New Zealand sea lions at Campbell Island/Motu Ihupuku: can it continue?

Abstract

New Zealand (NZ) sea lions (Phocarctos hookeri) were relisted as ‘nationally critical’ by the New Zealand Government in 2010, owing to recent severe declines in pup production at the Auckland Islands. However, research on Campbell Island/Motu Ihupuku indicates that this population's pup production is increasing. Between December 2009 and February 2010, surveys were undertaken aiming to determine production and early mortality rates (up to eight weeks) of NZ sea lion pups on Campbell Island. In total, 402 pups were tagged and a minimum pup production of 681 estimated from direct count. This estimate is 17% higher than the 2008 estimate of 583 pups and equates to 27% of the total pup production of the NZ sea lions in 2009–10. However, early pup mortality (55%) continues to be the highest recorded for any NZ sea lion breeding area and it is hypothesised that this breeding area is unlikely to be able to maintain this pup production increase.