| foraging energetics and diving behavior of lactating new zealand sea lions, phocarctos hookeri. | the new zealand sea lion, phocarctos hookeri, is the deepest- and longest-diving sea lion. we were interested in whether the diving ability of this animal was related to changes in its at-sea and diving metabolic rates. we measured the metabolic rate, water turnover and diving behavior of 12 lactating new zealand sea lions at sandy bay, enderby island, auckland islands group, new zealand (50 degrees 30's, 166 degrees 17'e), during january and february 1997 when their pups were between 1 and 2 mo ... | 2000 | 11060226 |
| aerobic dive limit: how often does it occur in nature? | diving animals offer a unique opportunity to study the importance of physiological constraint in their everyday behaviors. an important component of the physiological capability of any diving animal is its aerobic dive limit (adl). the adl has only been measured in a few species. the goal of this study was to estimate the aerobic dive limit from measurements of body oxygen stores and at sea metabolism. this calculated adl (cadl) was then compared to measurements of diving behavior of individual ... | 2001 | 11440864 |
| a comparison of salmonella serotypes isolated from new zealand sea lions and feral pigs on the auckland islands by pulsed-field gel electrophoresis. | the salmonella serotypes s. cerro and s. newport were isolated from new zealand sea lions (phocarctos hookeri) and feral pigs on the auckland islands in the new zealand subantarctic region. the isolates were typed by pulsed-field gel electrophoresis using xba1 as the restriction enzyme. the isolates were indistinguishable, which suggests that salmonella infection cycles between sea lions and pigs in this environment. apart from a previous isolation from a single new zealand fur seal (arctocephal ... | 2004 | 15465727 |
| new zealand sea lion (phocarctos hookeri) epidemic 2002 (abstract). | the new zealand sea lion is a threatened species and two unusual events contributed to a decrease in recruitment in 2002. the first was a marked reduction (20%) in the number of pups born at the principal auckland island rookeries. secondly, the mortality rate for pups was significantly elevated and was 33% by the end of february, almost three times the mean for that time of the year. counts of females at rookeries indicated that the lowered fecundity was possibly due to a scarcity of food resou ... | 2003 | 16032296 |
| first report and characterization of adult uncinaria spp. in new zealand sea lion (phocarctos hookeri) pups from the auckland islands, new zealand. | two species of hookworms (uncinaria lucasi and uncinaria hamiltoni) have been formally described from pinnipeds, but dissimilar types are noted from these hosts. this report is the first description of hookworms (uncinaria spp.) from the new zealand sea lion, phocarctos hookeri. the nematodes were collected from dead pups on enderby island (auckland islands, 50 degrees 30', 166 degrees 17') during january and february, 2004. standard measurements of male and female hookworms were obtained, provi ... | 2006 | 16362338 |
| characterization of klebsiella pneumoniae isolates from new zealand sea lion (phocarctos hookeri) pups during and after the epidemics on enderby island, auckland islands. | the 2001/2002 and 2002/2003 breeding seasons of new zealand sea lions (nzsls) on the auckland islands were marked by a high pup mortality caused by acute bacterial infections. as part of a health survey from 1998/1999 to 2004/2005, tissues and swabs of lesions had been collected at necropsy to identify the bacteria associated with pup mortality. klebsiella pneumoniae was grown in pure culture from 83% of various organs and lesions in 2001/2002 and 76% in 2002/2003, and less frequently in the fol ... | 2007 | 17250977 |
| epidemiology of hookworm (uncinaria spp.) infection in new zealand (hooker's) sea lion (phocarctos hookeri) pups on enderby island, auckland islands (new zealand) during the breeding seasons from 1999/2000 to 2004/2005. | this is the first investigation of the epidemiology of hookworm (uncinaria spp.) infection in new zealand sea lions (nzsls; phocarctos hookeri) on enderby island, auckland islands. the examination of faeces for hookworm eggs in various age categories of sea lions revealed that only pups up to at least 3 months of age harboured adult hookworms in their intestines. gross necropsy of more than 400 pups from 1999/2000 to 2004/2005 showed that the prevalence of hookworm infection varied significantly ... | 2007 | 17268806 |
| neonatal mortality in new zealand sea lions (phocarctos hookeri) at sandy bay, enderby island, auckland islands from 1998 to 2005. | as part of a health survey of new zealand sea lions (phocarctos hookeri) on enderby island, auckland islands (50 degrees 30's, 166 degrees 17'e), neonatal mortality was closely monitored at the sandy bay colony for seven consecutive years. throughout the breeding seasons 1998-99 to 2004-05, more than 400 postmortem examinations were performed on pups found dead at this site. the primary causes of death were categorized as trauma (35%), bacterial infections (24%), hookworm infection (13%), starva ... | 2007 | 17699084 |
| characterization of klebsiella pneumoniae isolates from new zealand sea lion pups. | | 2007 | 17875370 |
| humoral immune response to klebsiella spp. in new zealand sea lions (phocarctos hookeri) and the passive transfer of immunity to pups. | during the 2001-02 and 2002-03 breeding seasons, epizootics of klebsiella pneumoniae resulted in a dramatic increase of pup mortality in new zealand sea lions (phocarctos hookeri; nzsls) on enderby island (auckland islands). to estimate the prevalence of infection in the nzsl population, a serologic test was developed using a western blot and a polysaccharide antigen derived from a k. pneumoniae isolate from a nzsl pup. all archived serum samples collected between 1997 and 1998 and 2004 and 2005 ... | 2008 | 18263817 |
| serologic evaluation of new zealand sea lions for exposure to brucella and leptospira spp. | a serologic survey of anti-brucella and antileptospiral antibodies was conducted on 147 adult, female new zealand sea lions (phocarctos hookeri). most sea lions (n=138) were sampled at sandy bay, enderby island, auckland islands (50°30's, 166°17'e), january 2000-march 2005. nine were sampled at otago, new zealand (46°0's, 170°40'e); four in april 2008 and five in march 2009. serum from one of the enderby island females was weakly positive for antibodies to brucella abortus using the competitive ... | 2010 | 20966283 |
| examining the role of components of slc11a1 (nramp1) in the susceptibility of new zealand sea lions (phocarctos hookeri) to disease. | the new zealand sea lion (nzsl, phocarctos hookeri) is a threatened marine mammal with a restricted distribution and a small, declining, population size. the species is susceptible to bacterial pathogens, having suffered three mass mortality events since 1998. understanding the genetic factors linked to this susceptibility is important in mitigating population decline. the gene solute carrier family 11 member a1 (slc11a1) plays an important role in mammalian resistance or susceptibility to a wid ... | 2015 | 25874773 |
| extensive variation at mhc drb in the new zealand sea lion (phocarctos hookeri) provides evidence for balancing selection. | marine mammals are often reported to possess reduced variation of major histocompatibility complex (mhc) genes compared with their terrestrial counterparts. we evaluated diversity at two mhc class ii b genes, dqb and drb, in the new zealand sea lion (phocarctos hookeri, nzsl) a species that has suffered high mortality owing to bacterial epizootics, using sanger sequencing and haplotype reconstruction, together with next-generation sequencing. despite this species' prolonged history of small popu ... | 2013 | 23572124 |
| septicaemia and meningitis caused by infection of new zealand sea lion pups with a hypermucoviscous strain of klebsiella pneumoniae. | this study describes a syndrome of neonatal septicemia and meningitis in new zealand sea lions, caused by a strain of klebsiella pneumoniae that is phenotypically similar to strains causing environmentally-acquired septicemia and neuro-invasive disease in humans. between late 2006 and early 2010, 123 pups from the enderby island breeding colony died of k. pneumoniae infection, with lesions including fibrinous to fibrinosuppurative meningitis, subdural hemorrhage, septic arthritis, herniation and ... | 2015 | 25682024 |
| seroprevalence of toxoplasma gondii in mainland and sub-antarctic new zealand sea lion (phocarctos hookeri) populations. | to investigate the seroprevalence of antibodies to toxoplasma gondii in new zealand sea lions (phocarctos hookeri), as a potential contributor to reproductive failure. | 2016 | 27211206 |
| molecular systematics of pinniped hookworms (nematoda: uncinaria): species delimitation, host associations and host-induced morphometric variation. | hookworms of the genus uncinaria have been widely reported from juvenile pinnipeds, however investigations of their systematics has been limited, with only two species described, uncinaria lucasi from northern fur seals (callorhinus ursinus) and uncinaria hamiltoni from south american sea lions (otaria flavescens). hookworms were sampled from these hosts and seven additional species including steller sea lions (eumetopias jubatus), california sea lions (zalophus californianus), south american fu ... | 2013 | 24162075 |
| enamel ultrastructure of fossil and modern pinnipeds: evaluating hypotheses of feeding adaptations in the extinct walrus pelagiarctos. | this study aimed to assess the enamel ultrastructure in modern otariid pinnipeds and in the extinct walrus pelagiarctos. teeth of the new zealand fur seal (arctocephalus forsteri), sea lion (phocarctos hookeri), and fossil walrus pelagiarctos thomasi were embedded, sectioned, etched, and analyzed via scanning electron microscopy. the enamel of nz otariids and pelagiarctos was prismatic and moderately thick, measuring 150-450 μm on average. it consisted of transversely oriented hunter-schreger ba ... | 2016 | 27142598 |
| interspecies differences in plasma concentrations of 25-hydroxyvitamin d3 and dermal vitamin d synthesis of kiwi (apteryx mantelli), tuatara (sphenodon punctatus), and new zealand sea lions (phocarctos hookeri). | vitamin d plays a central role in calcium homeostasis of most vertebrates, and is obtained in different species through diet, dermal synthesis, or a combination of both. the aim of this study was to determine the predominant routes of vitamin d synthesis in three disparate species, brown kiwi (apteryx mantelli), tuatara (sphenodon punctatus), and new zealand sea lions (phocarctos hookeri). we surveyed plasma concentrations of 25-hydroxyvitamin d2 and d3, analysed environmental conditions and lif ... | 2017 | 28755031 |
| novel morphological and molecular data for corynosoma hannae zdzitowiecki, 1984 (acanthocephala: polymorphidae) from teleosts, fish-eating birds and pinnipeds from new zealand. | the polymorphid acanthocephalan, corynosoma hannae zdzitowiecki, 1984 is characterised on the basis of newly collected material from a new zealand sea lion, phocarctos hookeri (gray), and long-nosed fur seal, arctophoca forsteri (lesson) (definitive hosts), and from stewart island shags, leucocarbo chalconotus (gray), spotted shags, phalacrocorax punctatus (sparrman) and yellow-eyed penguins, megadyptes antipodes (hombron & jacquinot) (non-definitive hosts) from new zealand. specimens are descri ... | 2017 | 27765681 |
| redescription of antarctophthirus microchir (anoplura: echinophthiriidae) from the south american sea lion, otaria flavescens, from patagonia, argentina. | antarctophthirus microchir was originally described from phocarctos hookeri on the basis of 1 female and 1 male only. we redescribe adults and describe, for the first time, the 3 nymphal stages from specimens collected from otaria flavescens from patagonia, using light and scanning electron microscopy. the present material can be distinguished from other antarctophthirus species by the presence of a fringe of setae on the back of the head, only present in antarctophthirus trichechi and antarctop ... | 2009 | 19463036 |
| first report of systemic toxoplasmosis in a new zealand sea lion (phocarctos hookeri). | a 1-year-old female new zealand sea lion (phocarctos hookeri) was intermittently observed in the otago region of new zealand over an 11-month period, always dragging her hind flippers. in december 2012 the sea lion was found dead, after a period of several days being observed to be harassed by male sea lions. | 2017 | 27588458 |
| human-mediated extirpation of the unique chatham islands sea lion and implications for the conservation management of remaining new zealand sea lion populations. | while terrestrial megafaunal extinctions have been well characterized worldwide, our understanding of declines in marine megafauna remains limited. here, we use ancient dna analyses of prehistoric (<1450-1650 ad) sea lion specimens from new zealand's isolated chatham islands to assess the demographic impacts of human settlement. these data suggest there was a large population of sea lions, unique to the chatham islands, at the time of polynesian settlement. this distinct mitochondrial lineage be ... | 2016 | 27289078 |
| pathology and epidemiology of stillbirth in new zealand sea lions (phocarctos hookeri) from enderby island, auckland islands, 1998-2012. | stillbirth is a small and often cryptic fraction of neonatal mortality in mammals including pinnipeds. as part of an investigation into the poor reproductive success of the endangered new zealand sea lion (phocarctos hookeri), archived tissues from 37 stillborn pups born on enderby island between 1998 and 2012 were examined using histopathological techniques. apart from bronchopneumonia with neutrophilic infiltration in 4 cases, few inflammatory conditions were identified in stillborn pups. howe ... | 2016 | 27034387 |
| genetic evidence of a population bottleneck and inbreeding in the endangered new zealand sea lion, phocarctos hookeri. | the new zealand sea lion (nzsl) is of high conservation concern due to its limited distribution and its declining population size. historically, it occupied most of coastal new zealand, but is now restricted to a few coastal sites in southern mainland new zealand and the sub-antarctic islands. nzsls have experienced a recent reduction in population size due to sealing in the 1900s, which is expected to have resulted in increased inbreeding and a loss of genetic variation, potentially reducing th ... | 2016 | 26995741 |
| heterozygote advantage at mhc drb may influence response to infectious disease epizootics. | the effect of mhc polymorphism on individual fitness variation in the wild remains equivocal; however, much evidence suggests that heterozygote advantage is a major determinant. to understand the contribution of mhc polymorphism to individual disease resistance or susceptibility in natural populations, we investigated two mhc class ii b loci, dqb and drb, in the new zealand sea lion (nzsl, phocarctos hookeri). the nzsl is a threatened species which is unusually susceptible to death by bacterial ... | 2015 | 25728376 |
| extinction and recolonization of coastal megafauna following human arrival in new zealand. | extinctions can dramatically reshape biological communities. as a case in point, ancient mass extinction events apparently facilitated dramatic new evolutionary radiations of surviving lineages. however, scientists have yet to fully understand the consequences of more recent biological upheaval, such as the megafaunal extinctions that occurred globally over the past 50 kyr. new zealand was the world's last large landmass to be colonized by humans, and its exceptional archaeological record docume ... | 2014 | 24827440 |
| traumatic brain injury, axonal injury and shaking in new zealand sea lion pups. | trauma is a common cause of death in neonatal new zealand sea lion pups, and subadult male sea lions have been observed picking up and violently shaking some pups. in humans, axonal injury is a common result of traumatic brain injury, and can be due to direct trauma to axons or to ischaemic damage secondary to trauma. 'shaken baby syndrome', which has been described in human infants, is characterised by retinal and intracranial subdural haemorrhages, and has been associated with axonal injury to ... | 2014 | 24565687 |
| foraging behaviour of juvenile female new zealand sea lions (phocarctos hookeri) in contrasting environments. | foragers can show adaptive responses to changes within their environment through morphological and behavioural plasticity. we investigated the plasticity in body size, at sea movements and diving behaviour of juvenile female new zealand (nz) sea lions (phocarctos hookeri) in two contrasting environments. the nz sea lion is one of the rarest pinnipeds in the world. most of the species is based at the subantarctic auckland islands (ai; considered to be marginal foraging habitat), with a recolonizi ... | 2013 | 23671630 |
| sexual segregation in juvenile new zealand sea lion foraging ranges: implications for intraspecific competition, population dynamics and conservation. | sexual segregation (sex differences in spatial organisation and resource use) is observed in a large range of taxa. investigating causes for sexual segregation is vital for understanding population dynamics and has important conservation implications, as sex differences in foraging ecology may affect vulnerability to area-specific human activities. although behavioural ecologists have proposed numerous hypotheses for this phenomenon, the underlying causes of sexual segregation are poorly underst ... | 2012 | 23028978 |
| body regional distribution and stratification of fatty acids in the blubber of new zealand sea lions: implications for diet predictions. | fatty acids (fas) from blubber are often analysed to assess the diet of marine mammals. however, distribution of blubber fas is not necessarily uniform along the body. it is therefore important to understand the deposition of dietary fat to be able to estimate the diet. we analysed the fa compositions of the thoracic ventral (t region) blubber of 28 new zealand (nz) sea lions phocarctos hookeri by-caught by the southern arrow squid nototodarus sloani fishery. each blubber sample was divided into ... | 2013 | 22847500 |
| hookworm infection, anaemia and genetic variability of the new zealand sea lion. | hookworms are intestinal blood-feeding nematodes that parasitize and cause high levels of mortality in a wide range of mammals, including otariid pinnipeds. recently, an empirical study showed that inbreeding (assessed by individual measures of multi-locus heterozygosity) is associated with hookworm-related mortality of california sea lions. if inbreeding increases susceptibility to hookworms, effects would expectedly be stronger in small, fragmented populations. we tested this assumption in the ... | 2009 | 19605394 |
| [corynosoma hannae zdzitowiecki, 1984--a parasite of sea leopard from the pacific sector of antarctic]. | specimens of the acanthocephalan corynosoma hannae zdzitowiecki, 1984 from the pacific (balleni islands) and atlantic (south shetland) sectors of antarctic are compared with those from the pacific sector of subantarctic (auckland and campbell islands). probably new zealand sea lion phocarctos hookeri (gray, 1844) is the secondary definitive host for corynosoma hannae. description and figures of the specimens examined are provided. | 2007 | 17957958 |
| blood volume and diving ability of the new zealand sea lion, phocarctos hookeri. | we test the hypothesis that the new zealand sea lion is physiologically better equipped for prolonged, continuous diving than other otariids (fur seals and sea lions) by measuring its blood volume, an important component of its oxygen storage. mass, hematocrit, and plasma volume were measured and blood volume calculations were completed on 14 adult females and five juvenile females. plasma volume was determined using the evans blue dye dilution technique. mean plasma volume for all subjects was ... | 2006 | 9548653 |
| pup mortality in new zealand sea lions (phocarctos hookeri) at enderby island, auckland islands, 2013-18. | new zealand sea lions (phocarctos hookeri) are an endemic and endangered species. pup mortality at enderby island (50.5°s, 166.28°e) in the new zealand sub-antarctic has been well studied, with subsequent investigations yielding more intricate detail of the causes of mortality, as new diagnostic methods become available. klebsiella pneumoniae was first reported in 2001-02 at this site, causing a pup mortality epizootic and is now known to be present at several colonies. this bacterium is a commo ... | 2019 | 31751414 |
| pathology and molecular epidemiology of mycobacterium pinnipedii tuberculosis in native new zealand marine mammals. | mycobacterium pinnipedii causes tuberculosis in a number of pinniped species, and transmission to cattle and humans has been reported. the aims of this study were to: characterize the pathology and prevalence of tuberculosis in new zealand marine mammals; use molecular diagnostic methods to confirm and type the causal agent; and to explore relationships between type and host characteristics. tuberculosis was diagnosed in 30 pinnipeds and one cetacean. most affected pinnipeds had involvement of t ... | 2019 | 30753243 |
| causes of adult mortality in two populations of new zealand sea lions (phocarctos hookeri). | the new zealand sea lion is an endangered species endemic to new zealand. while causes of death are well described for pups of this species, mortality in adults is poorly characterised. this study investigated causes of death in 136 new zealand sea lions in two different populations: a major breeding site on remote, uninhabited enderby island in the sub-antarctic, and a slowly increasing recolonising population on the inhabited mainland. for animals with at least a partial diagnostic investigati ... | 2019 | 32734078 |
| draft whole-genome sequences of seven isolates of klebsiella pneumoniae from new zealand sea lions. | klebsiella pneumoniae is a gram-negative bacterium that may cause infection in a broad range of hosts. we report here the genome sequences of seven k. pneumoniae isolates from new zealand sea lions. | 2018 | 30533818 |
| no evidence of cryptic bycatch causing new zealand sea lion population decline. | | 2018 | 30135103 |
| reply to roberts et al.: faith in no fishery impact on new zealand sea lions based on misunderstandings and unsubstantiated claims. | | 2018 | 30135102 |
| marine mammal population decline linked to obscured by-catch. | declines of marine megafauna due to fisheries by-catch are thought to be mitigated by exclusion devices that release nontarget species. however, exclusion devices may instead conceal negative effects associated with by-catch caused by fisheries (i.e., unobserved or discarded by-catch with low postrelease survival or reproduction). we show that the decline of the endangered new zealand (nz) sea lion (phocarctos hookeri) is linked to latent levels of by-catch occurring in sub-antarctic trawl fishe ... | 2017 | 29078271 |