The primary objective of the population management plan for New Zealand sea lions, Phocarctos hookeri, is to move the species from its current conservation status of ‘Threatened’ to ‘Non-threatened’. The mechanism by which this will occur is through the establishment of new breeding colonies away from the only existing colonies at Auckland Islands and Campbell Island. Otago, on the southeast coast of the South Island of New Zealand, is one of only three locations where breeding has been recorded away from these islands in modern times. We found only one female at the initiation of our surveys here in 1991, an individual that had been tagged as a pup at Auckland Islands. This female has remained resident at Otago and is now breeding. Her first live birth, in the 1993/94 breeding season, represented the first record of a P. hookeri pup on the New Zealand mainland since the elimination of the species here by humans c. 150 years ago. Up to and including the 2000/01 breeding season she had produced six pups. Her surviving pups have remained at Otago and her eldest two daughters have started breeding, producing a further three pups. From this total of nine live births, two pups have died. Although 6 - 8 other migrant females have been recorded, to our knowledge none have bred at Otago. We conclude that the initiation of breeding by P. hookeri at Otago has been a serendipitous event attributable to atypical behaviour by a single female.
Campbell Island is the only major breeding site for the New Zealand sea lion Phocarctos hookeri outside the Auckland Islands. Minimum pup production was estimated at 78 for the 1997/98 breeding season, compared with the only previous estimate of 122 from 1991/92, and represents less than 5% of the total pup production for the species. Sea lions at Campbell Island have a widespread distribution, clumped at the coast and scattered inland. Local concentrations of sea lions were seen at Davis Point, Sandy Bay and both Northeast and Southeast Harbours. Isolated individuals were found up to 1.5 km inland and at altitudes up to 250 m. Breeding females at Campbell Island are generally solitary and give birth inland, in contrast to the highly gregarious colonies seen on the coasts of the Auckland Islands. In some years a small breeding colony forms on the coast, often at Davis point, but its location is variable. Overall, the present distribution and abundance of sea lions on Campbell Island does not appear to differ considerably from previous reports stretching back as far as the 1950s. Line transects proved inappropriate for estimating sea lion density, due to a low encounter rate and poor visibility in dense vegetation. Future work could include surveys for pups, which aggregate on the coast during March or April.
Nine weeks field work was completed during two trips in January/February and March/ April 2003 to investigate the distribution and abundance of New Zealand sea lion Phocarctos hookeri pups at Campbell Island. A total of 161 pups were tagged and a further 138 dead pups were found. A closed mark-recapture model was used to estimate the total number of live pups (e.g., tagged plus untagged pups) at Campbell Island in April as 247 (SE = 28,. Pup production at Campbell Island is estimated at 385, which comprises 13% of the total pup production for the species in the 2003 season. This is the first robust estimate of pup production for New Zealand sea lions at Campbell Island. The figure of 385 pups is considerably higher than any of the previous estimates reported from Campbell Island. The high level
The present management strategy for New Zealand sea lions Phocarctos hookeri assumes that kills in a squid trawl fishery around Auckland Islands, the species population base, have prevented an increase in abundance of sea lions. This strategy also assumes that emigration will be initiated as the population reaches carrying capacity, and that emigration rates will be density dependent. We used the combination of photographic identification of individuals and diagnostic features of age classes to estimate immigration rates of P. hookeri to Otago, South Island, New Zealand. Most immigrants were males ≤ 2 years old at arrival, and included animals tagged as pups at Auckland Islands. Estimates for total numbers of immigrants to Otago from four consecutive cohorts, 1991/92 -1994/95, varied three-fold through a period of constant annual pup production at Auckland Islands. The greatest influx was from the 1993/94 cohort, a breeding season that predated the enforcement of early closures of the squid fishery. We suggest published records from the Auckland Islands indicate that this population is already at carrying capacity. If so, then factors other than, or in addition to, pup production and fishery mortality have an impact on emigration rates.
1. Species' ranges are changing at accelerating rates. Species distribution models (SDMs) are powerful tools that help rangers and decision-makers prepare for reintroductions, range shifts, reductions and/or expansions by predicting habitat suitability across landscapes. Yet, range-expanding or -shifting species in particular face other challenges that traditional SDM procedures cannot quantify, due to large differences between a species' currently occupied range and potential future range. The realism of SDMs is thus lost and not as useful for conservation management in practice. Here, we address these challenges with an extended assessment of habitat suitability through an integrated SDM database (iSDMdb).2. The iSDMdb is a spatial database of predicted sites in a species' prediction range, derived from SDM results, and is a single spatial feature that contains additional, user-friendly data fields that synthesise and summarise SDM predictions and uncertainty, human impacts, restoration features, novel preferences in novel spaces and management priorities. To illustrate its utility, we used the endangered New Zealand sea lion Phocarctos hookeri. We consulted with wildlife rangers, decisionmakers and sea lion experts to supplement SDM predictions with additional, more realistic and applicable information for management.3. Almost half the data fields included in this database resulted from engaging with these end-users during our study. The SDM found 395 predicted sites. However, the iSDMdb's additional assessments showed that the actual suitability of most sites (90%) was questionable due to human impacts. >50% of sites contained unnatural barriers (fences, grazing grasslands), and 75% of sites had roads located within the species' range of inland movement. Just 5% of the predicted sites were mostly (>80%) protected.4. Integrating SDM results with supplemental assessments provides a way to address SDM limitations, especially for range-expanding or -shifting species. SDM products for conservation applications have been critiqued for lacking transparency and interpretation support, and ineffectively communicating uncertainty.This is an open access article under the terms of the Creat ive Commo ns Attri bution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
customersupport@researchsolutions.com
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
This site is protected by reCAPTCHA and the Google Privacy Policy and Terms of Service apply.
Copyright © 2025 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.