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POP2023-05 Auckland Islands New Zealand sea lions 2024-25 (PDF, 2,488K)
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 field team spent a total of eight weeks at the Auckland Islands (2 December 2024 – 25 January 2025): 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 conducted a mark-recapture survey and direct counts of pups. At Sandy Bay, Enderby Island, 283 pups were microchipped and 280 of those pups were also double-flipper tagged. At Dundas Island, 200 pups were double-flipper tagged. All 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.
Resightings of marked (flipper tagged/microchipped) animals of all age and sex classes were collected during daily dedicated surveys at Sandy Bay, Enderby Island, and opportunistically at Dundas and Figure of Eight Islands. Total counts of pups, females, sub-adult males, and adult males were undertaken daily at Sandy Bay, and weekly around the accessible areas of Enderby Island.
New Zealand sea lion pup production at the Auckland Islands in 2024/25 was estimated as 1376 ± 28 pups (mean ± 1 SE) which is lower than last year’s estimate of 1457 ± 19 pups and only slightly higher than the historic low of 1278 ± 23 pups reported in 2022/23 (Manno & Young 2023, Manno et al. 2024). This year’s pup production estimate again falls below the minimum level set to trigger review of the New Zealand sea lion Threat Management Plan (NZSL TMP) (DOC & MPI 2017).
The drop in pup production over the past three years could indicate a temporary reduction in breeding rate or a decline in survival or fecundity of this population of breeding females. The Department has been actively reviewing 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 as the Department reviews the New Zealand sea lion Threat Management Plan with Te Rūnanga o Ngāi Tahu and Fisheries New Zealand.
Publication information
Manno KL, Whyte J. 2025. New Zealand sea lion/pakake/whakahao field research report Auckland Islands 2024/25. Dunedin: Department of Conservation. 29 p.