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    Population dynamics and anthropogenic threats to New Zealand fur seal (Arctocephalus forsteri) in New Zealand : a thesis submitted in total fulfilment of the requirements for the degree of Doctor of Philosophy (PhD) in Veterinary Science at Massey University, Palmerston North, Aotearoa New Zealand
    (Massey University, 2025) Hall, Alasdair
    New Zealand fur seals (Arctocephalus forsteri; ‘NZFS’) are New Zealand’s most encountered pinniped. However, substantial gaps exist in the knowledge of their abundance and distribution. This study provides NZFS abundance and distribution data for Kaikōura and Banks Peninsula and investigates anthropogenic risks in both locations. Additionally, the thesis undertakes the first nationwide NZFS abundance estimate in ca. 50 years. The Kaikōura population study was the first since the 2016 earthquake. Kaikōura’s NZFS population has grown and spread post-earthquake, with an upper population estimate of 21,560 – 28,327 NZFS in the 2022/23 breeding season. However, pup production at Ōhau Point, the most impacted colony, has not grown, and breeding distribution has changed significantly. Following earthquake damage, State Highway 1 (SH1), which runs close to NZFS colonies, was reconstructed. This study detected an almost fivefold increase in the annual number of NZFS recorded on SH1 from 2012 – 2022, compared to 1996 – 2005. Ten statistically significant NZFS incident clusters were located, representing 89% of the incidents. Cluster location shifted following post-earthquake road reconstruction. Monthly NZFS incident numbers were significantly positively associated with traffic and windspeed, and significantly negatively associated with temperature and rainfall. Road-abutting NZFS breeding explained most of the spatial variation in NZFS incidents. An abundance estimate of 13,147 – 17,675 NZFS was calculated for Banks Peninsula in 2023/24, and 25 previously unrecorded colonies were assessed. This study considered response strategies for an oil spill impacting Banks Peninsula’s NZFS, as the region is classified as ‘high risk’ for such incidents. Priority response strategies include preventing oil from reaching colonies, and hazing individuals away from waterborne slicks. From the most recently available count data, a minimum nationwide population estimate of 131,338 – 168,269 NZFS was calculated. Using recent counts and stage-structured population modelling, a more reliable estimate of 181,646 – 239,473 NZFS was calculated, a substantial increase on the most cited nationwide abundance figure, 100,000 NZFS. This thesis’ population findings provide useful baselines and highlight the need for improved NZFS population monitoring. This is particularly important due to the changing human-NZFS relationship, evidenced by the Kaikōura road reconstruction and the risk of oil spills in Banks Peninsula.
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    Towards an Abundance Estimate for New Zealand Fur Seal in New Zealand
    (John Wiley and Sons Ltd, Hoboken, USA, 2025-04) Hall A; Chilvers BL; Weir JS; Burdett H
    A lack of population abundance and trajectory data is a conservation and management issue relevant to numerous pinniped species, many of which are exposed to a variety of threats. New Zealand fur seal (Arctocephalus forsteri; ‘NZFS’) populations in different parts of New Zealand have experienced both substantial increases and decreases to their abundance over the last 50 years, since the last nationwide census. Here, existing data and stage-structured matrix modelling were used to provide a contemporary nationwide estimate of NZFS abundance. Graphical depictions demonstrate the spatial inconsistencies in NZFS monitoring in New Zealand through time. A minimum population estimate of 131,338–168,269 NZFS was calculated by combining the most recently available pup production data from around New Zealand and using established multipliers. A second estimate of 181,646–239,473 NZFS was calculated using stage-structured matrix models to project contemporary abundance. Inconsistent NZFS population monitoring and sparse vital rate data for New Zealand's NZFS limited this study, and both population ranges are likely underestimates. However, they still represent substantial increases on the most cited nationwide abundance figure (100,000 NZFS). From these findings, we suggest that a regularised program of monitoring is adopted for New Zealand's NZFS, as has been achieved for similar species in other countries. This would both aid in the management of NZFS in the face of emerging risks, such as H5N1 avian influenza, and enable their use as a sentinel for the health of New Zealand's marine ecosystems.