Rate of passage of digesta through the alimentary tract of the New Zealand fur seal (Arctocephalus forsteri) and the Australian sea lion (Neophoca cinerea) (Carnivora : Otariidae)

1999 ◽  
Vol 47 (2) ◽  
pp. 193 ◽  
Author(s):  
B. Bodley ◽  
the late J. R. Mercer ◽  
M. M. Bryden

The inert marker titanium dioxide was added to the food of two male New Zealand fur seals (Arctocephalus forsteri) and three Australian sea lions (Neophoca cinerea) in Taronga Zoo, Sydney, in a series of 15 trials. The enclosures were checked constantly during daylight hours, and defaecation times and location of samples noted. Samples were collected at feeding times, at approximately 0930, 1300 and 1500 hours. During the night the animals were checked at 30-min intervals, the location of samples noted, and samples collected at the first feeding time next morning. Faecal collections were made for up to 50 h after dosing. Marker concentrations in faecal dry matter were determined and mean retention times calculated from the mean concentration-time curves. The mean time between dosing and first recovery of marker (Initial Recovery Time) was 4 h for A. forsteri and 6.5 h for N. cinerea. Mean retention time, a better index of rate of passage of digesta, was 14.6 h for A. forsteri and 14.9 h for N. cinerea. Thus, the marker concentration curves indicated a rapid rate of food transit through the gastrointestinal tract, as has been observed in several (but not all) pinniped species.

2010 ◽  
Vol 58 (2) ◽  
pp. 94 ◽  
Author(s):  
Peter D. Shaughnessy ◽  
Jane McKenzie ◽  
Melanie L. Lancaster ◽  
Simon D. Goldsworthy ◽  
Terry E. Dennis

Australian fur seals (Arctocephalus pusillus doriferus) breed on Bass Strait islands in Victoria and Tasmania. They have been recorded in South Australia (SA) for many years as non-breeding visitors and on Kangaroo Island frequently since 1988, mostly in breeding colonies of the New Zealand fur seal (A. forsteri) which is the most numerous pinniped in SA. Australian fur seals have displaced New Zealand fur seals from sections of the Cape Gantheaume colony on Kangaroo Island. North Casuarina Island produced 29 Australian fur seal pups in February 2008. Australian fur seal pups were larger than New Zealand fur seal pups in the same colony and have been identified genetically using a 263-bp fragment of the mitochondrial DNA control region. North Casuarina Island has been an important breeding colony of New Zealand fur seals, but pup numbers there decreased since 1992–93 (contrary to trends in SA for New Zealand fur seals), while numbers of Australian fur seals there have increased. This study confirms that Australian fur seals breed in SA. The two fur seal species compete for space onshore at several sites. Australian fur seals may compete for food with endangered Australian sea lions (Neophoca cinerea) because both are bottom feeders.


2005 ◽  
Vol 32 (1) ◽  
pp. 85 ◽  
Author(s):  
P. D. Shaughnessy ◽  
T. E. Dennis ◽  
P. G. Seager

Two seal species breed on the west coast of South Australia, the Australian sea lion, Neophoca cinerea, and the New Zealand fur seal, Arctocephalus forsteri. Aerial surveys were conducted at intervals of ~3 months between April 1995 and June 1997 to determine the breeding status of sea lions and timing of pupping seasons. Ground surveys between October 1994 and April 2004 aimed at counting sea lions and fur seals, particularly pups. In all, 27 sites were examined. Six new sea lion breeding colonies were documented, at Four Hummocks, Price, North Rocky, Dorothee, West Waldegrave and Nicolas Baudin Islands. All were found or confirmed by ground survey. Pup numbers were equivalent to 12% of the total number of pups estimated in surveys conducted from 1987 to 1992, but primarily in 1990. The sighting of brown pups on aerial surveys of Ward Island, Middle and Western Nuyts Reef supports earlier indications, based on dead pups, that they are breeding colonies. The timing of pupping seasons is not synchronous; estimates are presented for colonies between 1995 and early in 2004, with predictions to the end of 2005. The abundance estimates of sea lion pups highlight the importance of visiting a colony early in the pupping season to determine when pupping begins and ~5 months later when the maximum number of pups is expected. For the New Zealand fur seal, small numbers of pups were recorded at Dorothee, West Waldegrave and Nicolas Baudin Islands, and at Nuyts Reef. These and the previously unknown sea lion breeding colonies on the west coast of South Australia suggest that further colonies may remain to be documented. Because planning for aquaculture ventures is active in South Australia, it is important that the localities and status of sea lion and fur seal colonies be established unequivocally to ensure that the need for Prohibited Area status for islands with breeding colonies and for Marine Protected Areas around them is noted.


1999 ◽  
Vol 26 (3) ◽  
pp. 383 ◽  
Author(s):  
T. E. Dennis ◽  
P. D. Shaughnessy

In December 1996, a survey by helicopter of the Baxter Cliffs region of the Great Australian Bight in Western Australia did not locate any previously unreported colonies of the Australian sea lion or New Zealand fur seal. Although geologically contiguous with the Bunda Cliffs in South Australia (where sea lions have a scattered distribution), the Baxter Cliffs appeared generally more weathered and stable, with fewer collapsed sections of cliff forming platforms and providing habitat for seals. In total, 29 Australian sea lions were observed during the survey. Most were at a previously surveyed site approximately 2 km west of Twilight Cove. Ten other sites were recorded as potentially providing haul- out opportunity for sea lions; they were mainly caves and deep overhangs with access from the sea. No fur seals were seen. From this survey and from other records, we estimate the Australian sea lion population along the Baxter Cliffs in the Great Australian Bight region of Western Australia at less than 100 animals.


Author(s):  
Roger Kirkwood ◽  
Simon Goldsworthy

Fur seals and sea lions are charismatic, large carnivores that engage us with both their skill and playful antics. Although all species in Australian waters were harvested to near extinction 200 years ago, fur seals are recovering and are now common in near-shore waters across southern Australia. Sea lions, however, are endangered. Their populations appear not to have recovered like fur seals and are declining at some locations. Fur seals and sea lions are important top level predators and play an important role in Australia’s temperate marine ecosystems. Key threats they currently face relate to human activities, particularly interactions with fisheries. This book outlines the comparative evolutionary ecology, biology, life-history, behaviour, conservation status, threats, history of human interactions and latest research on the three species of otariids that live in the waters of southern Australia: the Australian fur seal, New Zealand fur seal and Australian sea lion. It also includes brief descriptions of Antarctic and Subantarctic seals that occupy the Antarctic pack-ice and remote Australian territories of Macquarie Island and Heard Island.


2007 ◽  
Vol 4 (1) ◽  
pp. 139-142 ◽  
Author(s):  
R.A Campbell ◽  
N.J Gales ◽  
G.M Lento ◽  
C.S Baker

Pinnipeds (seals, fur seals, sea lions and walrus) form large breeding aggregations with females often remaining faithful to a natal site or area. In these cases, females are philopatric to regional areas on broad geographical scales of hundreds to thousands of kilometres. An investigation of variation in a control region sequence of mtDNA in the Australian sea lion ( Neophoca cinerea ) has shown a case of extreme female natal site fidelity that has resulted in almost fixed population differentiation across its range ( Φ ST =0.93). This high level of population subdivision over short geographical distances (approx. 60 km) is unparalleled in any social marine mammal and reflects the unique life-history traits of this rare species. The high level of population subdivision and exclusive female natal site fidelity has important ramifications for conservation management, and poses many interesting questions of both academic and applied interest.


1996 ◽  
Vol 23 (6) ◽  
pp. 741 ◽  
Author(s):  
TE Dennis ◽  
PD Shaughnessy

In August 1994, a systematic survey of potential haulout sites of the Australian sea lion, Neophoca cinerea, was conducted along the coastline of the Great Australian Bight from Twin Rocks to Wilson Bluff, a distance of 206 km. A total of 289 Australian sea lions was recorded at 23 sites widely dispersed at the base of the Bunda Cliffs, hauled out on perched platforms formed by collapsed sections of cliff at various levels above the sea. Of these, 37 sea lions were recorded in a deep cave accessed from the sea. The total included 86 pups aged under 12 months, which were probably born in the region; six of these had almost completed moulting their natal pelage and were estimated to be near four months old. Only 12 New Zealand fur seals, Arctocephalus forsteri, were recorded. The Australian sea lion sites located in 1994 were surveyed again in August-September 1995, during a predicted breeding season. In this survey, a total of 284 sea lions was recorded at nine sites in South Australia and one site in Western Australia. This included 90 pups under six months of age, of which 44 were still in lanugo. Overall, we recorded 10 breeding sites and 14 haulout sites. Breeding events were recorded at one colony over three seasons and were consistent with an 18-month cycle. By extrapolating from the number of sea lion pups found in 1994, the population for the Great Australian Bight region in South Australia is estimated to be 613-774. This addition increases the previous estimate for South Australia by 9.3% and the previous total population estimate by 6.6%.


2003 ◽  
Vol 81 (2) ◽  
pp. 340-348 ◽  
Author(s):  
Linda L Milette ◽  
Andrew W Trites

Maternal attendance patterns of Alaskan Steller sea lions (Eumetopias jubatus) were compared during the summer breeding seasons in 1994 and 1995 at Sugarloaf Island (a declining population) and Lowrie Island (a stable population). Our goal was to determine whether there were differences in maternal attendance between the two populations that were consistent with the hypothesis that lactating Steller sea lions in the area of decline were food-limited during summer. Our a priori expectations were based on well-documented behavioural responses of otariids to reduced prey availability. We found that foraging trips were significantly shorter in the area of population decline, counter to initial predictions. The mean length of foraging trips in the declining area was 19.5 h compared with 24.9 h in the stable area. In contrast, the mean perinatal period (time between parturition and first feeding trip) was significantly longer in the area of decline (9.9 versus 7.9 days), again countering initial predictions. The mean length of shore visits for the declining population was also significantly longer (27.0 h compared with 22.6 h where the population was stable). For both populations, the mean time that mothers foraged increased as pups grew older, whereas the time that they spent on shore with their pups became shorter. Behavioural observations of maternal attendance patterns are inconsistent with the hypothesis that lactating Steller sea lions from the declining population had difficulty obtaining prey during summer.


2000 ◽  
Vol 203 (23) ◽  
pp. 3655-3665 ◽  
Author(s):  
D.P. Costa ◽  
N.J. Gales

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 months old. Metabolic rate (rate of CO(2) production) and water turnover were measured using the (18)O doubly-labeled water technique, and diving behavior was measured with time/depth recorders (TDRs). Mean total body water was 66.0+/−1.1 % (mean +/− s.d.) and mean rate of CO(2) production was 0. 835+/−0.114 ml g(−)(1)h(−)(1), which provides an estimated mass-specific field metabolic rate (FMR) of 5.47+/−0.75 W kg(−)(1). After correction for time on shore, the at-sea FMR was estimated to be 6.65+/−1.09 W kg(−)(1), a value 5.8 times the predicted standard metabolic rate of a terrestrial animal of equal size. The mean maximum dive depth was 353+/−164 m, with a mean diving depth of 124+/−36 m. The mean maximum dive duration was 8.3+/−1.7 min, with an average duration of 3.4+/−0.6 min. The deepest, 550 m, and longest, 11.5 min, dives were made by the largest animal (155 kg). Our results indicate that the deep and long-duration diving ability of New Zealand sea lions is not due to a decreased diving metabolic rate. Individual sea lions that performed deeper dives had lower FMRs, which may result from the use of energetically efficient burst-and-glide locomotion. There are differences in the foraging patterns of deep and shallow divers that may reflect differences in surface swimming, time spent on the surface and/or diet. Our data indicate that, although New Zealand sea lions have increased their O(2) storage capacity, they do not, or cannot, significantly reduce their at-sea metabolic rates and are therefore likely to be operating near their physiological maximum.


2014 ◽  
Vol 36 (2) ◽  
pp. 154 ◽  
Author(s):  
Peter D. Shaughnessy ◽  
Catherine M. Kemper ◽  
David Stemmer ◽  
Jane McKenzie

Two fur seal species breed on the southern coast of Australia: the Australian fur seal (Arctocephalus pusillus doriferus) and the New Zealand fur seal (A. forsteri). Two other species are vagrants: the subantarctic fur seal (A. tropicalis) and the Antarctic fur seal (A. gazella). We document records of vagrant fur seals in South Australia from 1982 to 2012 based primarily on records from the South Australian Museum. There were 86 subantarctic fur seals: 49 specimens and 37 sightings. Most (77%) were recorded from July to October and 83% of all records were juveniles. All but two specimens were collected between July and November. Sightings were prevalent during the same period, but there were also nine sightings during summer (December–February), several of healthy-looking adults. Notable concentrations were near Victor Harbor, on Kangaroo Island and Eyre Peninsula. Likely sources of subantarctic fur seals seen in South Australia are Macquarie and Amsterdam Islands in the South Indian Ocean, ~2700 km south-east and 5200 km west of SA, respectively. There were two sightings of Antarctic fur seals, both of adults, on Kangaroo Island at New Zealand fur seal breeding colonies. Records of this species for continental Australia and nearby islands are infrequent.


2007 ◽  
Vol 29 (1) ◽  
pp. 103 ◽  
Author(s):  
R.R. McIntosh ◽  
M.D. Murray

Sea lions (Neophoca cinerea) at several South Australian islands were infested with the anopluran louse Antarctophthirus microchir.


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