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 2009Á10. 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.

Winter foraging behaviour of lactating New Zealand sea lions (Phocarctos hookeri)

“…New Zealand sea lions breed predominately (99.9%) on the Auckland and Campbell/Motu Ihupuku islands in the New Zealand subAntarctic between latitudes 488S and 538S (Gales & Mattlin 1997;Chilvers et al 2007). Pup production of NZ sea lions at the Auckland Islands (73% of the species; Maloney et al 2012) has declined by more than 40% since 1998. Fisheries interactions both direct (by-catch) and indirect (resource competition) are considered the most plausible hypotheses for this decline (Robertson & Chilvers 2011;Chilvers 2012).…”

GIS-based multi-criteria analysis of breeding habitats for recolonising species: New Zealand sea lions

“…1). The results of this study provides the sole terrestrial habitat preference knowledge for the species along with some anecdotal references that can also be found in other publications (Marlow, 1975;Chilvers and Wilkinson, 2008;Maloney et al, 2012). These results provide a the best available details on the types of habitat features that New Zealand sea lions require to form a breeding colony at a particular site.…”

“…Due to a limited geographic distribution and a declining population, P. hookeri (previously known as the Hooker's sea lion) has been identified as a conservation priority for the New Zealand Department of Conservation (DOC) (Baker et al, 2010). Only three breeding colonies exist, two in the Auckland Islands, where 73% of pups are born each season (Robertson and Chilvers, 2011), and the other on Campbell Island (Maloney et al, 2012) (Fig. 1).…”

Conservation needs for the endangered New Zealand sea lion, Phocarctos hookeri

“…Figure of Eight Island (50°46′S, 166°01′E) is the second main pupping area at the Auckland Islands (Chilvers et al, ). The last recognized pupping area is at Campbell Island (52°33′S, 169°09′E) at Davis and Paradise Points either side of the entrance to Perseverance Harbour at Campbell Island (Maloney et al, ). There are a further three sites where pupping is or was known to occur: (1) the Otago Peninsula/Catlins area, South Island, NZ; (2) Snares Island; and (3) Stewart Island (Figure ).…”

“…1995; Gales & Fletcher, ). However, apart from pup production estimates at the Auckland Islands, methods and timing of monitoring of NZ sea lions population dynamics, pup production, resighting effort of tagged animals, understanding mortality and many other essential aspects of their biology have changed, with the timing and length of field seasons at all breeding areas (Childerhouse et al, ; Maloney, Chilvers, Muller, & Haley, ; Maloney et al, ) including for the last 3 years at the Auckland Islands changing annually (Childerhouse, , , ).…”