Vagrant Subantarctic fur seal in the Mayumba National Park,Gabon

A vagrant adult male Subantarctic fur seal Arctocephalus tropicalis was seen and photographed on the beach in Mayumba National Park in the Gabonese Republic. This is the northern most sighting on record for the species. The likely source of the vagrant is the population at Gough Island, South Atlantic.     

Serengeti III: Human Impacts on Ecosystem Dynamics

During a survey of seals in September and October 2009 at Gough Island, South Atlantic Ocean, we recorded goose barnacles (Lepas australis) attached to the pelage of two of the 12 elephant seals (Mirounga leonina) inspected and one of the seven vagrant Antarctic fur seals (Arctocephalus gazella) which were found amongst the resident Subantarctic fur seals (A. tropicalis). We also recorded a goose barnacle attached to a Northern rockhopper penguin (Eudyptes chrysocome moseleyi).     

Geographical Distribution of African Mammals

This is a report of a marine predator (the white shark) being threatened by a member of the species on which it preys (a male Cape fur seal). Although these events may be rarely observed or occur infrequently, they may have important implications for the predator and its prey.We suggest that shark mobbing by adult male Cape fur seals is adaptive for the reduction of risk of predation by sharks. Mobbing of sharks is likely to alert conspecifics to the presence of a predator, and/or reduce the shark's hunting motivation near the mobbing site.     

A record of the sub-Antarctic fur seal Arctocephalus tropicalis in Angola

Two individuals of the sub-Antarctic fur seal, Arctocephalus tropicalis, one of which was photographed, were seen on the beach 1 km south of the mouth of the Kwanza River, Angola, on 2 October 1983. This record represents a northerly extension by some 2 700 km of the previously recorded range. The nearest breeding colony is at Tristan da Cunha about 4 000 km south-west of this sighting.     

Prevalence of Coxiella burnetii and Brucella spp. in tissues from subsistence harvested northern fur seals (Callorhinus ursinus) of St. Paul Island,Alaska

Background

The northern fur seal (Callorhinus ursinus) is an important cultural and nutritional resource for the Aleut community on St. Paul Island Alaska. In recent years, an increasing number of zoonotic pathogens have been identified in the population, but the public health significance of these findings is unknown. To determine the prevalence of Coxiella burnetii and Brucella spp. in northern fur seal tissues, eight tissue types from 50 subsistence-harvested fur seals were tested for bacterial DNA by real-time polymerase chain reaction.

Findings

Of the 400 samples tested, only a single splenic sample was positive for Brucella spp. and the cycle threshold (ct) value was extremely high suggesting a low concentration of DNA within the tissue. C. burnetii DNA was not detected.

Conclusions

Findings suggest that the risk of humans contracting brucellosis or Q fever from the consumption of harvested northern fur seals is low.     

Current prevalence of adult Uncinaria spp. in northern fur seal (Callorhinus ursinus) and California sea lion (Zalophus californianus) pups on San Miguel Island, California, with notes on the biology of these hookworms

A prevalence survey for hookworms (Uncinaria spp.) was done in northern fur seal (Callorhinus ursinus) and California sea lion (Zalophus californianus) pups on San Miguel Island, CA, in 2000. Intestines of dead pups were examined for adult hookworms in July. These parasites were found in 95% of 20 fur seal pups and 100% of 31 sea lion pups. The number of hookworms varied from 4 to 2142 (mean = 760) in fur seal pups and from 20 to 2634 (mean = 612) in sea lion pups. A direct relationship was evident between body condition and number of hookworms in the pups; that is, pups in poor condition had fewer hookworms than those in good condition. There was a decline in the number of hookworms in sea lion pups in 2000 compared to collections in 1996. Eggs of Uncinaria spp. were found in rectal feces (collected in late September and early October) of none of 35 (0%) live fur seal pups and 41 of 48 (85%) live sea lion pups. Packed cell volume values, determined for most of the same live pups, were essentially normal for C. ursinus but were much lower than normal for most Z. californianus. Hookworm larvae were not found in blubber of fur seal and sea lion pups or in rookery sand in July. Rookery sand, positive for live hookworm larvae when put in a refrigerator, was negative at removal 2.5 years later. The average number of eggs in utero of female hookworms was 285 for three specimens from a fur seal pup and 281 from three specimens from a sea lion pup. One hookworm larva was recovered from milk stripped from the teats of a stranded Z. californianus female at The Marine Mammal Center, Sausalito, CA.     

Pathology and bacteriology of adult male Antarctic fur seals, Arctocephalus gazella, dying at Bird Island, South Georgia

A high mortality rate occurs in Antarctic fur seal males on the breeding breaches of Bird Island, South Georgia. The main causes of death were infections of fighting wounds and pneumonias. The bacteria involved appear to be opportunistic pathogens, predominantly various strains of streptococci.     

Inshore occurrence of southern right whales (Eubalaena australis ) at Subantarctic Marion Island

Opportunistic shore-based sightings of southern right whales Eubalaena australis for Marion Island (46°54’S, 37°45’E) were documented at five different times between 1974 and 2009. Whales were sighted between May and September and exclusively on the eastern lee side of the Island. Notwithstanding some observer biases over this time frame, the species appears to be an infrequent visitor to the inshore marine environment of Marion Island.     

Preliminary investigation of a possible lung worm (Parafilaroides decorus), fish (Girella nigricans), and marine mammal (Callorhinus ursinus) cycle for San Miguel sea lion virus type 5

Colostrum-deprived neonatal Northern fur seal pups (Callorhinus ursinus) were exposed to San Miguel sea lion virus type 5 (SMSV-5) by feeding them fish (Girella nigricans) infected with virus or fish infected with both the sea lion lung worm larvae (Parafilaroides decorus) and virus. Virus infection was demonstrated in 8 of 9 pups, and 1 of these developed a vesicular lesion on the flipper. In this sequence, P decorus larvae exposed to SMSV-5 were fed to G nigricans held at 15 C in a salt water aquarium; 32 days later, these fish were killed, then fed to the fur seal pups. The vesicle developed 22 days subsequent to this and SMSV-5 was reisolated from the lesion. The SMSV-5 was shown to persist for at least 23 days in infected neonatal fur seals. Attempts to establish P decorus infection in Northern fur seal pups were apparently unsuccessful.     

New Zealand's cetaceans and pinnipeds

The 8 species of baleen whale in New Zealand waters range in length from 6 to 30+ metres, and the 25 species of toothed whale range up to 18 metres. A single porpoise species is known in New Zealand sub-Antarctic waters. The baleen whales and many of the toothed whales are migratory, and New Zealand straddles their well-defined routes: a combination which allowed whaling to flourish. The toothed whales are the more gregarious and may indulge in mass strandings. Current research aims to investigate the biology of all of the whale species. The otariid, or eared seals found in the New Zealand region are the New Zealand sealion and the New Zealand fur seal. The commonest of the phocid, or earless seals on the New Zealand coast are the elephant and leopard seals. All of these breed in the southern parts of the region but range further north. The fur seal population is rising slowly, but the small population size of the New Zealand sealion gives cause for concern. Marine mammals form an important part of the fauna of the New Zealand region, and veterinary knowledge and general research should be increased.     

Bilateral ocular anomalies in a South African fur seal (Arctocephalus pusillus pusillus)

A female South African fur seal (Arctocephalus pusillus pusillus) began having obvious clinical ophthalmologic problems by 8 weeks of age. The initial clinical sign was diffuse corneal edema, which progressed to bullae formation and ulcers; the underlying cause of corneal edema and bullous keratopathy was not identified antemortem. An ophthalmological evaluation was performed when the fur seal was approximately 6 months of age, but due to the diffuse corneal edema, intraocular structures could not be easily evaluated. An underlying infectious etiology was suspected; therefore, appropriate diagnostics were pursued, but did not identify a cause. Initial improvement was noted, but the fur seal then became blind and eventually became very painful. Due to decreased quality of life and aggressive behavior, the fur seal was euthanized. Histopathological diagnoses were persistent tunica vasculosa lentis and persistent hyperplastic primary vitreous with bilateral hypermature resorbed cataracts and retinal detachments with rosette formation.     

Serological survey of pre-weaned New Zealand fur seals (Arctocephalus forsteri) for brucellosis and leptospirosis

AIM: To conduct a longitudinal serological survey for evidence of Brucella spp and Leptospira spp infection of pre-weaned New Zealand fur seals in a colony on the Otago Peninsula. METHODS: Seal pups were repeatedly captured on a monthly basis from February through to July 2001. Pups were tagged at first capture and a blood sample was taken at each capture event. A total of 163 sera were collected from 118 seal pups. Where sufficient volume was collected, the sera were tested for leptospirosis using the microscopic agglutination test (MAT), and for brucellosis using the competitive enzyme-linked immunosorbent assay (ELISA) for Brucella abortus. RESULTS: None of 128 sera from 101 seals tested positive to the ELISA for B. abortus. All tests for Leptospira interrogans serovars Grippotyphosa, Copenhageni, Bratislava and Leptospira borgpetersenii serovar Ballum were negative at a cut-off of <1/100 dilution. Positive or suspicious titres were found to L. interrogans serovars Canicola and Pomona and L. borgpetersenii serovar Hardjo. The highest titres (12,800) were found to serovar Pomona. The titre to serovar Pomona in one seal rose from <1/50 in March to 12,800 in April and was <1/50 when re-sampled in July. The titre to serovar Pomona in another seal dropped from 12,800 in May to <1/50 in June. These seals also had titres to serovar Hardjo, which rose or fell in the same manner. All suspicious or positive titres occurred in late April and early May, when the pups were approximately 4-5 months old. In June and July, all seals tested were negative. CONCLUSIONS: There was no serological evidence of Brucella infection in the pre-weaned fur seals at the colony. Positive titres to serovars Pomona, Hardjo, or Canicola suggest that a Leptospira species was present at the colony, however isolation or visualisation of the organism is required to confirm this. Care should be exercised when handling New Zealand fur seals to prevent human infection or inadvertent transfer of leptospirosis to another marine mammal species.     

New Zealand’s Cetaceans and Pinnipeds

The 8 species of baleen whale in New Zealand waters range in length from 6 to 30+ metres, and the 25 species of toothed whale range up to 18 metres. A single porpoise species is known in New Zealand sub-Antarctic waters.

The baleen whales and many of the toothed whales are migratory, and New Zealand straddles their well-defined routes: a combination which allowed whaling to flourish. The toothed whales are the more gregarious and may indulge in mass strandings. Current research aims to investigate the biology of all of the whale species.

The otariid, or eared seals found in the New Zealand region are the New Zealand sealion and the New Zealand fur seal. The commonest of the phocid, or earless seals on the New Zealand coast are the elephant and leopard seals. All of these breed in the southern parts of the region but range further north. The fur seal population is rising slowly, but the small population size of the New Zealand sealion gives cause for concern.

Marine mammals form an important part of the fauna of the New Zealand region, and veterinary knowledge and general research should be increased.     

Identification of novel DNA fragments and partial sequence of a genomic island specific of Brucella pinnipedialis

Since the 1990s, Brucella strains have been isolated from a wide variety of marine mammals and were recently recognized as two different species, i.e. Brucella pinnipedialis for pinniped isolates and Brucella ceti for cetacean isolates. The aim of this study was to identify specific DNA fragments of marine mammal Brucella strains using a previously described infrequent restriction site-PCR (IRS-PCR) method but with three new couples of restriction enzymes applied on a larger panel of marine mammal Brucella isolates (n=74) and one human isolate from New Zealand likely from marine mammal origin. This study revealed five DNA fragments specific of Brucella strains isolated from marine mammals. Among them two new DNA fragments were specific of B. pinnipedialis but were not detected in hooded seal isolates. DNA fragment I identified in the previous IRS-PCR study and fragment VI of this study were located on a cloned and sequenced 6kb SacI fragment. Its nucleotide sequence revealed that it is likely part of a putative genomic island. Sequence analysis showed that it carries four ORFs coding for putative metabolic functions. Although hooded seal isolates are classified within B. pinnipedialis it was shown in this study that they do not carry this genomic island and this raises the question about their evolutionary history within B. pinnipedialis.     

White shark (Carcharodon carcharias)-inflicted bite wounds observed on Cape fur seals (Arctocephalus pusillus pusillus) at Black Rocks,Algoa Bay,South Africa

This paper presents the first quantitative study on the seasonal occurrence and body location of white shark (Carcharodon carcharias)-inflicted injuries on Cape fur seals (Arctocephalus pusillus pusillus) at Black Rocks, in Algoa Bay. Between January 2010 and October 2011, 22 boat trips were made to Black Rocks to chum for white sharks. On 19 of the trips a series of overlapping photographs were taken of the northern side of Black Rocks and the percentage of seals, which exhibited fresh white shark bite wounds recorded. A total of 53 sharks and 28 fresh shark-inflicted injuries were recorded on seals over the course of the study period. The maximum number of sharks sighted per hour (1.2) was in July and the highest percentage of shark bitten seals in November (0.6%). There was no significant relationship between the monthly sighting rate of sharks and the percentage of shark bitten seals (P = 0.40). The percentage of shark-inflicted injuries observed on seals increased with seal size. Most injuries were observed in the forebody (37.5%) and lower body regions (37.5%). Very few injuries (6.3%) were observed in the head and neck region. The low number of bite-inflicted injuries observed suggests that white sharks attack seals infrequently at Black Rocks.     

Serological survey of pre-weaned New Zealand fur seals (Arctocephalus forsteri) for brucellosis and leptospirosis

AIM: To conduct a longitudinal serological survey for evidence of Brucella spp and Leptospira spp infection of pre-weaned New Zealand fur seals in a colony on the Otago Peninsula.

METHODS: Seal pups were repeatedly captured on a monthly basis from February through to July 2001. Pups were tagged at first capture and a blood sample was taken at each capture event. A total of 163 sera were collected from 118 seal pups. Where sufficient volume was collected, the sera were tested for leptospirosis using the microscopic agglutination test (MAT), and for brucellosis using the competitive enzyme-linked immunosorbent assay (ELISA) for Brucella abortus.

RESULTS: None of 128 sera from 101 seals tested positive to the ELISA for B. abortus. All tests for Leptospira interrogans serovars Grippotyphosa, Copenhageni, Bratislava and Leptospira borgpetersenii serovar Ballum were negative at a cut-off of <1/100 dilution. Positive or suspicious titres were found to L. interrogans serovars Canicola and Pomona and L. borgpetersenii serovar Hardjo. The highest titres (12,800) were found to serovar Pomona. The titre to serovar Pomona in one seal rose from <1/50 in March to 12,800 in April and was <1/50 when re-sampled in July. The titre to serovar Pomona in another seal dropped from 12,800 in May to <1/50 in June. These seals also had titres to serovar Hardjo, which rose or fell in the same manner. All suspicious or positive titres occurred in late April and early May, when the pups were approximately 4–5 months old. In June and July, all seals tested were negative.

CONCLUSIONS: There was no serological evidence of Brucella infection in the pre-weaned fur seals at the colony. Positive titres to serovars Pomona, Hardjo, or Canicola suggest that a Leptospira species was present at the colony, however isolation or visualisation of the organism is required to confirm this. Care should be exercised when handling New Zealand fur seals to prevent human infection or inadvertent transfer of leptospirosis to another marine mammal species.     

Helicobacter spp. from gastric biopsies of stranded South American fur seals (Arctocephalus australis)

Gastrointestinal lesions with uncertain etiology have been widely described among pinnipeds. The aim of our study was to investigate the presence of Helicobacter spp. in the gastric mucosa of South American fur seals (Arctocephalusaustralis). Gastric biopsies from thirteen seals, stranded on the shores of the Southwestern Atlantic Ocean in Argentina, were evaluated for the presence of Helicobacter spp. by PCR and DNA sequence analysis. Six gastric biopsies were positive for Helicobacter spp. Pairwise sequence comparisons showed less than 95% identity to novel Helicobacter spp. described from pinnipeds from North America and Australia. However, phylogenetic analysis revealed that the South American fur seal sequences clustered with 99-100% homology with H. cetorum, a species isolated from dolphins and whales. The presence of H. cetorum in pinnipeds, if confirmed by its isolation from the gastric mucosa of these mammals, demonstrates the wide host range of this bacterium in the marine environment.     

Freshwater invertebrates of sub-Antarctic Marion Island

The freshwater habitats (mires, streams, lakes, pools and wallows) on sub-Antarctic Marion Island were examined for invertebrates. Sixty-eight species were found, including 45 new records for the Island. Of these 56 were bona fide aquatic invertebrates, the rest being terrestrial or brackish interlopers that had fallen or been blown into the water. The aquatic species include five platyhelminthes, a gastrotrich, three tardigrades, 28 rotifers, six nematodes, two annelids and 11 arthropods. Most are familiar species that have been recorded on other sub-Antarctic islands. The invertebrate faunas of the various freshwater habitats were basically similar in species composition, with the abundances of particular species dependent upon the water body’s size, distance from the sea and degree of eutrophication resulting from seal and seabird manuring.     

Comparison of age determination techniques for known-age Cape fur seals

Known-age teeth were used to validate age determination techniques for the Cape fur seal (Arctocephalus pusillus pusillus). Thin sectioning and staining of decalcified teeth produced the poorest age estimates. For etched half canines, only upper canines could be used to estimate age with good results, and coating improved the accuracy. Scanning electron microscopy produced poor accuracy in age estimation. External ridges reflected age accurately only in younger age classes and should only be used to verify counts of internal growth layer groups, or when rapid, preliminary estimates of age are necessary. This study has highlighted the importance of comparing different age determination techniques and validating such techniques with known-age animals. The reliability with which age can be estimated for the Cape fur seal has also been improved.     

Vesicular exanthema of swine and San Miguel sea lion virus: experimental and field studies in otarid seals, feeding trials in swine

The naturally occurring disease caused by San Miguel sea lion virus in fur seals was characterized by small fluid-filled vesicles 1 to 25 mm in diameter on the nonhaired portions of the flippers. Early epithelial lesions contained multifocal sites of cell lysis. The resultant microvesicles enlarged and coalesced, forming grossly visible macrovesicles. Mature vesicles progressed to involve all layers of the epithelium but did not involve the underlying dermis. Intradermal inoculation of vesicular exanthema of swine virus type A48 or San Miguel sea lion virus type 2 into otarid (fur) seal pups caused plaque-like lesions around inoculated coronary bands. These swellings regressed without rupture by 96 hours postinoculation. One seal inoculated with San Miguel sea lion virus had a linear lingual erosion at ten days postinoculation. Virus was isolated from this site and from two uninoculated sites, the tonsil and testicle. Contact controls showed no evidence of infection. Virus was isolated in low titers from some sites of inoculation and draining lymph nodes from seals infected with vesicular exanthema of swine virus. Virus was recovered more easily, in higher titers, and from more tissues, from seals infected with San Miguel sea lion virus. Inoculated seals tested after four to ten days seroconverted. Feeding swine seal tissues from the inoculation experiments resulted in seroconversion in swine which were fed tissues from seals infected with vesicular exanthema of swine virus but not in those which were fed tissues from seals infected with San Miguel sea lion virus.