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POP2023-05 Auckland Islands New Zealand sea lions 2025-26 (PDF, 1,173K)
Summary
This report summarises fieldwork undertaken by the Department of Conservation (DOC) Marine Bycatch and Threats team as part of Conservation Services Programme (CSP) project POP2023-05 ‘Auckland Islands New Zealand sea lions’ (DOC 2024).
The DOC CSP-funded team spent a total of seven weeks at the Auckland Islands undertaking sea lion research and active management (8 December 2025 to 23 January 2026), which comprised six weeks at Enderby Island, three nights on Dundas Island, and one day on Figure of Eight Island. Direct counts of pups were undertaken each day at Sandy Bay, Enderby Island. At Dundas Island, the team conducteda mark-recapture survey and direct counts of pups. At Sandy Bay, Enderby Island, 297 pups were microchipped and 295 of those pups were also double flipper-tagged. At Dundas Island, 200 pups were double flipper-tagged, and 100 of those pups were microchipped. Female pups born at Sandy Bay, Enderby Island, were treated with a subcutaneous injection of ivermectin (a deworming medication) at approximately one week of age, in accordance with a veterinary operating instruction (VOI). A second DOC team, funded directly by DOC’s Marine Bycatch and Threats team, were deployed to Enderby Island from 15 January to 12 March 2026 to conduct investigations into pup survivorship and mortality,
and to continue the programme of active management to recover this population.
Resightings of marked animals of all age and sex classes were collected during daily dedicated surveys at Sandy Bay, Enderby Island, and opportunistically at other areas of the Auckland Islands, from November 2025 to March 2026. Total counts of pups, females, sub-adult males, and adult males were undertaken daily at Sandy Bay up to 16 January 2026, and weekly around accessible areas of Enderby Island.
New Zealand sea lion pup production at the Auckland Islands in 2025/26 was estimated as 1,425 ± 30 pups (mean ± 1 SE), which is higher than last year’s estimate of 1,375 pups, but lower than the estimate of 1,457 pups in 2023/24 (Manno et al. 2024; Manno & Whyte 2025).
The drop in pup production over the past four years suggests a recent decline in survival or fecundity of this population of breeding females, which can be investigated using resighting and productivity information. DOC has recently reviewed management actions to recover the New Zealand sea lion population, and the decision to treat pups with ivermectin at Enderby Island is a direct result of that review. Further management actions will be considered by DOC in partnership with Te Rūnanga o Ngāi Tahu and Fisheries New Zealand.
The increase in the number of tourist vessel landings and numbers of passengers landed per day since 2016, in addition to the timing of landings at Enderby Island during periods critical for wildlife breeding and research, had substantial impacts on the team’s ability to complete their work this year. The period between the cessation of pup birthing on and post-colonial movement away from the Auckland Islands harems is a narrow biological window of ten days (10 to 20 January annually). Changes to tourist vessel schedules, allowing access to Sandy Bay during the pup tagging period, resulted in difficulty achieving pup tagging, counts, and active management safely. A review of tourist access is required to ensure that conservation management activity is prioritised at these islands during critical time periods.
Publication information
Whyte, J., Manno, K. and Young, M. 2026. New Zealand sea lion/pakake/whakahao Auckland Islands 2026-26. Conservation Services Programme, Department of Conservation, Wellington, Aotearoa New Zealand. 25 p.