Arctocephalus Forsteri Research Articles

Multisystemic toxoplasmosis associated with a type II-like Toxoplasma gondii strain in a New Zealand fur seal (Arctocephalus forsteri) from New South Wales, Australia

We report the first confirmed case of toxoplasmosis in an Australian pinniped. Presence of Toxoplasma gondii DNA was detected in the brain of a free-ranging subadult New Zealand fur seal (Arctocephalus forsteri) with nonsuppurative meningoencephalitis, hypophysitis, posterior uveitis, retrobulbar cellulitis, and myocarditis associated with protozoan cysts and tachyzoites. The emaciated seal stranded moribund on a beach in northern Sydney in New South Wales. Histopathology coupled with specific immunohistochemistry and PCR assays confirmed the presence of T. gondii. The T. gondii sample (NZfs8825) identified in this study has an identical genotype as the type II (ToxoDB PCR-RFLP genotype #1) based on the direct sequencing and virtual RFLP of multilocus DNA markers including SAG1, 5′- and 3′-SAG2, alt.SAG2, SAG3, BTUB, GRA6, c22-8, c29-2, L358, PK1, and Apico. Direct sequencing of T. gondii B1 DNA marker from the T. gondii sample (NZfs8825) identified a type II-like strain, based on presence of non-archetypal B1 gene polymorphisms previously reported as unique to Australia. This study suggests that T. gondii oocysts originating from mainland Australia, which has a large population of feral cats, may act as a disease threat to native marine fauna. Therefore, emerging toxoplasmosis in the Arctic has a relevant parallel in the Southern Ocean within Australian waters with yet unknown relevance to Antarctica.

THE SEAL TUBERCULOSIS AGENT, MYCOBACTERIUM PINNIPEDII, INFECTS DOMESTIC CATTLE IN NEW ZEALAND: EPIDEMIOLOGIC FACTORS AND DNA STRAIN TYPING

The fur seal (Arctocephalus forsteri), which is abundant in coastal areas of New Zealand, harbors several zoonotic pathogens, including Mycobacterium pinnipedii, a member of the Mycobacterium tuberculosis complex. We describe the microbiology and epidemiology of seven cases of M. pinnipedii infection in beef cattle (Bos primigenius) in coastal areas of New Zealand in 1991-2011. Epidemiologic factors were analyzed on six case farms and a telephone survey of 55 neighboring farms. A DNA-strain typing, using analysis of variable number tandem repeats and the direct repeats (VNTR/DR) of those isolates, was used to compare them to M. bovis isolates commonly found in New Zealand cattle and wildlife. In all cases of M. pinnipedii in cattle, only one animal in the herd was found to be infected. In six of seven cases, the lesions were in the thoracic lymph nodes, indicating a likely aerosol pathway. The lack of multiple cases within a herd suggests that cow-to-cow transmission is uncommon, if it occurs at all. There was no significant difference between case and control farms in distance to sea, herd size, herd type, or farming practice. The odds ratio for access to the beach for cattle on the Chatham Islands was significantly higher than it was for farms on the mainland coastal areas (odds ratio [OR] = 3.6, 95% CI = 1.1-11.4) Likewise, the odds ratio for acquiring tuberculosis was increased when farmers had seen seals on the property (OR = 9, 95% CI = 1.4-56.1 ). In all case farms, cattle had access to seals by beach grazing areas or waterways connecting directly with the ocean. The VNTR/DR typing of the isolates showed some variation in the M. pinnipedii isolates, with only two being identical; all isolates were easily distinguishable from M. bovis isolates.

Changes in the abundance and distribution of the New Zealand fur seal (Arctocephalus forsteri) in Western Australia: are they approaching carrying capacity?

New Zealand fur seals have been increasing in abundance across Australia over the past 20 years, with annual population growth rates of 10–15%. Recent changes in distribution in Western Australia suggested that the population was increasing and expanding in range beyond the known historical distribution. We aimed to determine the growth rate of individual colonies and the overall population across Western Australia and identify new breeding and haulout sites. We used the direct count technique to estimate New Zealand fur seal pup production at 17 breeding sites. We estimated pup production to be 3518 in the 2010/11 austral summer, producing a resultant population estimate of ~17 200 New Zealand fur seals in Western Australia. This represented an exponential growth rate over the past 12 years of ~1% per annum, a significant reduction from the estimated rate of 10% per annum between 1989 and 1999. There were clusters of colonies that showed large annual declines of 6–7% in pup production over the past 12 years and at other colonies maximal rates of increase of pup production were 6–9% per annum. Three new breeding colonies were discovered. It appears that the New Zealand fur seal population is nearing its carrying capacity in Western Australia.

Contrast in the importance of arrow squid as prey of male New Zealand sea lions and New Zealand fur seals at The Snares, subantarctic New Zealand

New Zealand sea lions (Phocarctos hookeri) are threatened by incidental bycatch in the trawl fishery for southern arrow squid (Nototodarus sloanii). An overlap between the fishery and foraging sea lions has previously been interpreted as one piece of evidence supporting resource competition for squid. However, there is currently no consensus about the importance of squid in the diet of New Zealand sea lions. Therefore, we investigated this importance independently of spatial and temporal differences in squid availability through a simultaneous study with sympatric New Zealand fur seals (Arctocephalus forsteri), a species known to target arrow squid. Diet sampling at The Snares (48°01′S 166°32′E), subantarctic New Zealand, in February 2012 coincided with peak annual catch in the nearby squid fishery. Diets were deduced by analyses of diagnostic prey remains from scats (faeces) and casts (regurgitations). The contribution of each prey species to the diet was quantified using the per cent index of relative importance (% IRI) that combined frequency of occurrence, mass and number of prey items. Arrow squid was a minor component in sea lion scats (2 % IRI), and none was found in their casts. In contrast, arrow squid was the major component in fur seal scats and casts (93 and 99 % IRI, respectively). This study found that New Zealand sea lions ate minimal squid at a time when squid was clearly available as evidenced by the diet of New Zealand fur seals; hence, there was no indication of resource competition between sea lions and the squid fishery.

Zooarchaeological and Stable Isotopic Assessments on Pinniped–Human Relations in the Beagle Channel (Tierra del Fuego, Southern South America)

ABSTRACTRecent zooarchaeological investigations in the Beagle Channel region have shown long‐term variations characterised by a high inter‐taxonomic dominance of pinnipeds during the first moments of the archaeological sequence (ca 6400 bp) at the Túnel Locality and a decrease in the relative importance of this resource and a diversification of subsistence in that place since 5500 bp. Two possible explanations for these variations are evaluated: (i) variations in foraging habits of pinnipeds that would lead to changes in the degree of predictability or access to the resource and (ii) a reduction in resource availability because of increased human predation pressure. To analyse these arguments, this paper presents and discusses the results of an analysis of stable isotopes (δ13C and δ15N) from collagen samples of South American fur seals (Arctocephalus australis) and representations of age and size of pinnipeds in the archaeological record of Túnel. Stable isotope analyses suggest that there were variations in the foraging behaviour of southern fur seals at the same time that zooarchaeological analyses record decreases of the ages and sizes of the hunted prey. On the basis of these results, an increase of hunter–gatherer predation pressure on pinnipeds to the Middle–Late Holocene in southern South America is suggested. Copyright © 2013 John Wiley & Sons, Ltd.

Morphometric and molecular characterization of the species of Uncinaria Frölich, 1789 (Nematoda) parasitic in the Australian fur seal Arctocephalus pusillus doriferus (Schreber), with notes on hookworms in three other pinniped hosts

This study presents morphological and molecular data on hookworms from the Australian fur seal Arctocephalus pusillus doriferus (Schreber) currently identified in Australian waters as Uncinaria hamiltoni Baylis, 1933. Additional specimens from the Australian sea lion Neophoca cinerea (Péron) and the New Zealand fur seal Arctocephalus forsteri (Lesson) from Australia, and the Southern elephant seal Mirounga leonina (Linnaeus) from Antarctica, were included. Using the internal transcribed spacer (ITS), hookworms from A. p. doriferus, N. cinerea and A. forsteri were found to be genetically similar but distinct from Uncinaria spp. found in M. leonina from Antarctica, as well as from Zalophus californianus (Lesson) and Callorhinus ursinus (Linnaeus) from California. Few morphological differences were detected between these taxa.

Palaeoenvironmental reconstruction of La Olla, a Holocene archaeological site in the Pampean coast (Argentina)

The evolution of littoral palaeoenvironments in the southern Pampas region of Argentina towards the end of the early Holocene and the beginning of the mid Holocene is discussed, and the formation processes of the archaeological site of La Olla are analysed. This site is located in the intertidal zone of the present beach and is remarkably well-preserved. The human occupation at the site has been dated at between 7400 and 6480 yrs BP, and is interpreted as a place for the processing and consumption of the southern fur seal (Arctocephalus australis) and southern sea-lion (Otaria flavescens). It is concluded that biostabilization by microbial mats of the sedimentary structures and archaeological remains that developed and are present on the tidal flat prevented their erosion by wind, turbulence currents and waves. This is what has permitted the exceptional preservation of the site. On the basis of the analyses of one of the sectors of the site it can be concluded that the sedimentary succession of the La Olla site is the result of the coastal environmental changes during the early–mid Holocene in the pre-maximum transgressive episode. During this interval a tidal flat developed on the Pleistocene abrasion platform. Human occupation occurred during the formation of mixohaline marsh, an upper intertidal–lower supratidal zone ecosystem.

Freezing and thawing of pinniped carcasses results in artefacts that resemble traumatic lesions

The objective of this study was to assess whether the freezing and thawing of pinniped carcasses prior to post-mortem examination could create artefacts that resembled lesions caused by trauma. Necropsy findings in New Zealand fur seals (Arctocephalus forsteri), captured incidental to commercial fishing, and either chilled (n=5) or frozen (n=5), were compared. Changes in frozen, but not in chilled, carcasses included: pseudo-bruising of subcutis; the accumulation of thick dark red fluid (resembling haemorrhage) in the thoracic cavity, pericardial sac and abdominal cavity; apparent subcapsular renal haemorrhage; pseudo-contusions of the brain; apparent haemorrhage from the nares; and blood-staining of the anterior ocular chamber. The processes of freezing and thawing were strongly associated with subcutaneous pseudo-bruises, the presence of thick, dark red abdominal fluid and renal subcapsular 'haemorrhage' (P=0.004). These artefacts probably develop due to a combination of autolysis and 'freeze-thaw' effects including lysis of cell membranes, fluid shifts into the extracellular space, and disruption of blood vessel walls. The results of the study demonstrate that artefacts resembling traumatic lesions are created during freezing and thawing of pinniped bodies. Such changes must be taken into consideration at post-mortem examination of previously frozen carcasses.

Unusual stability of diet of the New Zealand fur seal (Arctocephalus forsteri) at Banks Peninsula, New Zealand

The diet of the New Zealand fur seal Arctocephalus forsteri was determined from examination of scats and regurgitates collected from two breeding colonies at Banks Peninsula, Canterbury. Identifiable otoliths and squid beaks were obtained from 392 scats and 16 regurgitations collected over four seasons in 2008. Nine species were identified in scats and three species were identified in regurgitates. Arrow squid (Nototodarus sloanii) accounted for the greatest proportion of biomass taken (>90%), followed by lanternfish (Lampanyctodes hectoris and Symbolophorus sp.; 4%) and barracouta (Thyrsites atun; 2.6%). Although slight differences in diet were detected spatially and temporally, both colonies had a squid-dominated diet year round. This differs from the seasonal dietary variation shown in other areas around mainland New Zealand.

The assessment of lethal propeller strike injuries in sea mammals

Assessment of injuries in marine mammals may be required to help authorities determine whether human activity was involved. Three cases of marine animal deaths involving propeller blade strikes are reported to demonstrate characteristic features of such cases and diagnostic difficulties that may occur. Case 1: A juvenile New Zealand fur seal (Arctocephalus forsteri) suffered two parallel linear incised wounds of the flank and died following small intestinal herniation. Case 2: An Indo-Pacific bottlenose dolphin neonate (Tursiops aduncus) died from a deeply incised wound of the left side of the head with shattering of the skull and laceration of the underlying brain.Case 3: An adult female Indo-Pacific bottlenose dolphin (T. aduncus) died from two parallel chop wounds to the torso with opening of the thoracic and abdominal cavities with fractures of the ribs and vertebrae. Given that some animals may recover, and that the carcasses of those that are killed may simply not be found or reported, it is impossible to provide an estimate of the incidence of this type of injury amongst wild sea mammals. In cases that do come to forensic attention accurate evaluation of the type of injury may potentially have great medicolegal significance. Post-mortem putrefaction and post-mortem feeding by other sea animals may complicate assessments.

The potential role of forensic pathologists in veterinary forensic medicine

There has been an increasing awareness over recent years of the field of veterinary forensic medicine, with involvement of veterinarians in a wide range of activities extending from the assessment of possible inflicted injuries in domestic animals to wildlife crime concerning the entrapment, transport and killing of protected and endangered species [1, 2]. More publications are occurring in this area, with for example, a special issue of Forensic Science Medicine and Pathology being recently devoted to wildlife crime, and comprehensive textbooks now emerging [2–4]. The opportunity for forensic pathologists to contribute to this area is also being increasingly recognized [5]. The link between human forensic pathology and that involving animals is obvious and the opportunity to foster collaboration between these two areas of practice should be seized upon, as information and techniques utilized by forensic pathologists may be of great use in veterinary practice. As forensic pathologists are exposed on a daily basis to lethal injuries and processes, they also have a wealth of information that can be shared with veterinary colleagues who may not have such intense exposure to this type of material. It is quite obvious that forensic pathologists with training in human disease and injury have a great deal to learn from veterinary colleagues, and that many of the dissections and conditions encountered will be completely outside their experience. However, certain conditions affecting both humans and animals may show common features, and as lethal episodes in humans may have been studied more extensively than in non-humans, cross-species comparison of cases may provide a useful guide for the possible investigation of nonhuman fatalities. A good example of this was a young adult male Indian Ocean Bottlenose dolphin (Tursiops cf aduncus) that was found dead with a small Cobbler Carpetshark (Sutorectus tentaculatus) wedged firmly within its upper aerodigestive tract. Known as cafe coronary syndrome in humans, this type of death raised the possibility of neurological impairment and prompted a search for intrinsic central nervous system disease, or heavy metal poisoning in the affected animal [6]. The use of human imaging modalities, such as CT scanning, in animals with significant injuries may demonstrate more clearly the nature of the injuries than standard dissection or skeletal defleshing. For example, comminuted fracturing of the midfacial skeleton in a juvenile New Zealand fur seal (Arctocephalus forsteri) was far more clearly shown by CT scanning prior to necropsy than afterwards, as the delicate central facial skeleton had collapsed once supporting fascia and soft tissues had been removed [7]. Unfortunately techniques routinely used in humans, such as immunohistochemical staining of tissues for microscopy using anti-human reagents may not always work in animals [8], although on occasion there may be a surprising degree of cross reactivity [9]. Another area that forensic pathologists can contribute to is in lecturing to veterinary science students on basic injury assessment and evaluation. A patterned abrasion, a stab R. W. Byard (&) Discipline of Anatomy and Pathology, Level 3 Medical School North Building, The University of Adelaide, Frome Road, Adelaide 5005, Australia e-mail: roger.byard@sa.gov.au

Invasive species in penguin worlds: An ethical taxonomy of killing for conservation

This paper explores various attempts to manage predation threats to an endangered population of little penguins (<i>Eudyptula minor</i>) living in Sydney's North Harbour. Some of these threats have come from species that are generally termed 'exotic' (such as the red fox, <i>Vulpes vulpes</i>), while other threats have potentially come from 'natives' (such as the New Zealand fur seal, <i>Arctocephalus forsteri</i>). This paper explores the problematic notion of 'invasiveness' as it applies to native and introduced predators, and the role that these rhetorical distinctions play in positioning various species as 'threats' to the continuity of this penguin colony. In particular, the paper is concerned with conservation legislation and practice in New South Wales, and the unique kind of 'ethical work' done by these processes of classifying living things. Finally, the paper asks, in the absence of a simplistic-but helpful-correlation between exotic and invasive species, how might we understand and justify the conservation of an isolated colony of little penguins? What kinds of interventions (from humans and nonhumans) are warranted, and which are not? What might it mean to genuinely inhabit these difficulties, making conservation decisions outside of any space of simple and absolute answers?

How Effective are Posted Signs to Regulate Tourism? An Example with New Zealand Fur Seals

Increased tourism has augmented harassment to wildlife and posted signs are commonly used to manage such interactions. This study determined whether signs increased tourist compliance with regulations to remain &gt;10 m from New Zealand fur seals (Arctocephalus forsteri) at Kaikoura Peninsula. We observed 362 tourist groups interacting with seals. The percentage of groups in which all members respected the posted distance was similar whether tourists saw the signs or not [60.6% vs. 65.9%; G(1) = 0.98, p = 0.32]. Results indicate that posted signs were ineffective in increasing compliance to regulations and suggest that alternative approaches must be considered to increase regulation compliance and better manage interactions between tourists and wildlife.

Effects of the Presence of Official-Looking Volunteers on Harassment of New Zealand Fur Seals

An increased number of tourists viewing animals in the wild have increased stress on these animals (hereafter wildlife). Many wildlife-viewing locations rely on voluntary compliance with posted regulations to protect animals from tourists because of the expense of employing on-site enforcement personnel. Voluntary compliance, however, is ineffective. The presence of official-looking volunteers may decrease the incidence of wildlife harassment by tourists. To test this possibility, we observed tourists interacting with 5- to 12-month-old New Zealand fur seals (Arctocephalus forsteri) at the popular Ohau Stream waterfall while in the absence or presence of a young woman in plain sight wearing a neon vest (i.e., observer) and when an observer was not present. We observed 254 tourist groups at the waterfall when young seals were present. The percentage of groups in which at least one person harassed (approached, touched, or threw objects) a young seal was two-thirds lower when the official-looking observer was present. Frequency of harassment was inversely related to observer presence. Programs in which volunteers work at tourist sites are popular in countries with high tourism rates, such as New Zealand. Our results show that a relatively inexpensive and effective tourism-management strategy may be to post such volunteers as observers at sites where tourists view wildlife.

Fish feed on faeces and vomits of New Zealand fur seals: marine mammals bring nutrients from open to inshore waters

New Zealand fur seals ( Arctocephalus forsteri ) forage mostly in open waters at night and spend parts of the day in coastal sheltered sites, where they may play, rest and eliminate wastes. We recorded the purple wrasse ( Notolabrus fucicola ) feeding on faeces and vomits of these pinnipeds at Fortescue Bay in the Tasman Peninsula, Australia. This behaviour allows the wrasse to get nutrients from open waters that otherwise would not be available. Thus, it is suggested that the fur seals have the role of transferring nutrients from open waters to inshore reefs and provide them as particulate food to fish. This functional role is apparently recorded for only one species of marine mammal so far, the spinner dolphin ( Stenella longirostris ), in tropical oceanic waters.

Numerical anomalies in the dentition of southern fur seals and sea lions (Pinnipedia: Otariidae)

Cases of dental agenesis, supernumerary teeth and dental losses are presented in three species of South American Otariids: Arctocephalus australis (Zimmermann, 1783), A. tropicalis (Gray, 1872) and Otaria flavescens (Shaw, 1800). For the first time, congenital and acquired dental anomalies were comparatively diagnosed in skull samples from southern Brazil and nearby areas. The skulls and mandibles were accessed in the scientific collection of mammals of the Federal University of Santa Catarina, southern Brazil. Agenesis was found only among maxillary post-canine teeth, especially the distal ones (PC/6), due to an evolutionary trend towards reduction of the number of post-canine teeth in this family. Maxillary and mandibular supernumerary teeth were found in A. australis and A. tropicalis, but their positioning is unrelated to cases regarding phylogenetic and evolutionary implications. Dental losses were found in all species and different stages of alveolar obliteration suggest that this process is common in Otariids and does not affect their survival. The investigation of congenital and acquired dental anomalies in pinnipeds can provide information on dental formula evolution in Pinnipeds and in the phylogenetic relationships among Carnivora.

Mechanisms of deaths in captive juvenile New Zealand fur seals (Arctocephalus forsteri)

Juvenile seals are sometimes encountered in waters around South Australia with injuries and/or diseases that require veterinary treatment. Two cases are reported where apparently stable animals died soon after being rescued due to quite disparate conditions. In Case 1 a juvenile male New Zealand fur seal (Arctocephalus forsteri) was found unexpectedly dead in its enclosure. A necropsy examination revealed an emaciated juvenile male with no injuries. The intestine was filled throughout its length with melena stool that was due to heavy infestation of the stomach with roundworms with adjacent gastritis. Death was due to shock from upper gastrointestinal blood loss secondary to parasitosis. In Case 2 a second juvenile male New Zealand fur seal (Arctocephalus forsteri) also died unexpectedly in its enclosure. It had been listless with loud respirations since capture. At necropsy there was no blood around the head, neck or mouth, and no acute external injuries were identified. An area of induration was, however, present over the snout with fragmentation of underlying bones. The maxilla was freely mobile and CT scanning revealed multiple comminuted fractures of the adjacent facial skeleton. Examination of the defleshed skull showed fragmentation of the facial skeleton with roughening of bones in keeping with osteomyelitis. Death was attributed to sepsis from osteomyelitis of a comminuted midfacial fracture. These cases demonstrate two unusual and occult conditions that may be present in recently retrieved juvenile fur seals. Failure to establish the correct diagnosis rapidly may result in death soon after capture. The usefulness of imaging techniques such as CT scanning in delineating underlying injuries prior to necropsy is clearly demonstrated.

Agonistic Behaviour in Female New Zealand Fur Seals, Arctocephalus forsteri

New Zealand fur seals, Arctocephalus forsteri, breed in densely packed colonies where males hold exclusive territories. Both sexes overheat while on land and use shade and pools of water for cooling. In addition, females are aggressive towards one another and rarely tolerate neighbours closer than 1 m away. At a New Zealand colony of this species, agonistic interactions among females occurred most often in areas used for thermoregulation: shaded rock substrate and pools of water. Fewest interactions occurred in sunny, dry areas. These findings suggest that females are competing for a limited resource, which could limit harem size.

Observations of mortality of fur seals between 1998 and 2005 in Tasmania, Australia

Because of their often close relationship with the human environment, the deaths of marine mammals are often documented, particularly if there are links to anthropogenic influences. Between 1998 and 2005 a total of 504 dead Australian Fur Seals, Arctocephalus pusillus doriferus, and New Zealand Fur Seals, Arctocephalus forsteri, were reported in Tasmanian waters. Ninety individuals (18%) were dependent unweaned pups that had been displaced from their natal colonies. Of the 209 adult or subadult seals for which the cause of death could be ascertained,anthropogenic activities were identified as being responsible for the deaths of 172 individuals (82%), with 112 (53%) associated with fish farms. Most fish farm-related deaths occurred during the winter when adult and subadult seals were away from breeding colonies and seal numbers are highest around farms. The next most common cause of death was from firearms (41 individuals - 20%). Death of adults and subadults by natural causes accounted for 37 animals, or 18% of all deaths for which the cause was identified. Excluding pups, most seals were identified as Australian (80%) or New Zealand fur seals (3%). The remainder (17%) were identified as fur seals but not to species. Males were most common (58%), with only 6% identified as females; the sex of 36% could not be determined. Of the males, 106 (26%) were adults and 98 (24%) were subadults or juveniles.

Calibrations to estimate absolute numbers of New Zealand fur seal (Arctocephalus forsteri) pups from direct counts

Annual direct counts of seal pups can indicate long‐term trends in population size, but mark‐recapture estimates are needed to deduce absolute numbers. A calibration between results from these two methods would facilitate the use of direct counts to estimate absolute numbers, an outcome that is relatively quick, cheap and minimises disturbance of animals. Mark‐recapture estimates for the numbers of New Zealand fur seal (Arctocephalus forsteri) pups in 2003 at 10 colonies at Otago, southeastern New Zealand, were compared with independent single counts at the same colonies. A single ratio to estimate absolute numbers (y) from direct counts x was not statistically significant. Instead, two ratios were deduced, based on differences in habitat among colonies: y = 1.51x for colonies with hiding places for pups and y = 0.96x for colonies without hiding places. Application of these calibrations and their 95% prediction intervals produce estimates and ranges for the absolute numbers of pups from single annual counts.