NZ sea lion monitoring at the Auckland Islands 2019/20

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POP2018-03: NZ sea lion monitoring at the Auckland Islands 2019/20 (PDF, 1,626K)

Summary

This report outlines components of New Zealand sea lion (NZSL) population monitoring work
on the Auckland Islands as a part of the wider NZSL Threat Management Plan (TMP).
This work consists of two major components:

• Population monitoring (i.e. pup production) funded by the Conservation Services
  Programme (CSP), and
• Population demographics and pup mortality work funded by the NZSL Threat
  Management Plan (TMP).

Plans for the season were significantly impacted, reducing a field season of commonly six weeks to ten days. During the 2019/20 field season, total pup production was estimated at 1,740 for the Auckland Islands. This estimate is 3.6% higher than the 2018/19 estimate of 1,679, continuing the relatively stable trend over the past 12 years since the lowest pup production recorded in 2008/09. Total pup production was estimated at 289 on Enderby Island (Sandy Bay n=289; South East Point n=0); 1,398 at Dundas Island; and 53 at Figure of Eight Island.

Flipper tags were used to permanently mark 510 pups (284 at Enderby, 200 at Dundas, and 26 at Figure of Eight). All tagged pups on Enderby were microchipped but no chipping was done on Dundas or Figure of Eight. One hundred pups at Dundas Island, 98 pups at Sandy Bay, and 26 pups at Figure of Eight Island were weighed and measured. Sea lion pup mortality investigations were only planned for carcasses found on Enderby and only one gross postmortem was completed during the 2019/20 season. The cause of death for this pup was inconclusive due to moderate decomposition and extensive scavenging of the carcass. 

Publication details

Melidonis, M.C. and Childerhouse, S. 2020. New Zealand Sea Lion (Rāpoka) Monitoring on the Auckland Islands for the 2019/20 Season: Field Research Report. Prepared for the Department of Conservation (DOC). 23p.