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Journal articles on the topic 'Cape fur seal'

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Published: 4 June 2021

Last updated: 28 January 2023

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1

Strydom, Zanri, Lauren J. Waller, Mark Brown, Hervé Fritz, Kevin Shaw, and Jan A. Venter. "Factors that influence Cape fur seal predation on Cape gannets at Lambert’s Bay, South Africa." PeerJ 10 (June 13, 2022): e13416. http://dx.doi.org/10.7717/peerj.13416.

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Seabird populations experience predation that can impact their breeding density and breeding success. The Cape gannet Morus capensis is endemic to the Benguela upwelling ecosystem and is classified as Endangered by the IUCN. They are affected by several threats, including predation by the Cape fur seal Arctocephalus pusillus pusillus. Many fledglings succumb to predation during their maiden flight across waters around the island. To curb predation, the selective culling of individual predatory seals was implemented in 2014, 2015, and 2018. Our first study objective was to determine if selective culling of Cape fur seals significantly reduced predation probability on Cape gannets. We tested whether predation probability in 2014, 2015, and 2018 was affected by fish biomass, gannet fledgling numbers, and/or the presence/absence of selective culling. Our second objective was to determine what led to fluctuations in Cape fur seal predation on Cape gannet fledglings between 2007 and 2018. We tested whether fish biomass and the amount of Cape gannet fledglings in the water affected predation probability on the fledglings. Results indicated that selective culling reduced predation within years. We found that with both increased fledgling numbers and increased fish biomass, seal predation probability was reduced. This suggests that a sustainable way to promote the conservation of Cape gannets would be to increase food availability for both the Cape fur seals and Cape gannets. Our findings, collectively with the global trend of the declining Cape gannet population and their endemism, provide reasons advocating for the conservation of the food resources of both the Cape fur seal and the Cape gannet in the Benguela system.

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2

Shaughnessy, Peter D., Jane McKenzie, Melanie L. Lancaster, Simon D. Goldsworthy, and Terry E. Dennis. "Australian fur seals establish haulout sites and a breeding colony in South Australia." Australian Journal of Zoology 58, no. 2 (2010): 94. http://dx.doi.org/10.1071/zo10017.

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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.

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3

martin, r. aidan, neil hammerschlag, ralph s. collier, and chris fallows. "predatory behaviour of white sharks (carcharodon carcharias) at seal island, south africa." Journal of the Marine Biological Association of the United Kingdom 85, no. 5 (October 2005): 1121–35. http://dx.doi.org/10.1017/s002531540501218x.

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between 1997 and 2003, there were 2088 natural predations by white sharks (carcharodon carcharias) on cape fur seals (arctocephalus pusillus pusillus) and 121 strikes on towed seal-shaped decoys were documented from observation vessels at seal island, south africa. white sharks at seal island appear to selectively target lone, incoming young of the year cape fur seals at or near the surface. most attacks lasted <1 min and consisted of a single breach, with predatory success rate decreasing rapidly with increasing duration and number of subsequent breaches. a white shark predatory ethogram, composed of four phases and 20 behavioural units, is presented, including four varieties of initial strike and 11 subsequent behaviour units not previously defined in the literature. behaviour units scored from 210 predatory attacks revealed that, for both successful and unsuccessful attacks, polaris breach was the most commonly employed initial strike, while surface lunge was the most frequent second event, closely followed by lateral snap. examination of video footage, still images, and tooth impressions in decoys indicated that white sharks at seal island bite prey obliquely using their anterolateral teeth via a sudden lateral snap of the jaws and not perpendicularly with their anterior teeth, as previously supposed. analysis of white shark upper tooth morphology and spacing suggest the reversed intermediate teeth of white sharks occur at the strongest part of the jaw and produce the largest wound. white shark predatory success at seal island is greatest (55%) within one hour of sunrise and decreases rapidly with increasing ambient light; the sharks cease active predation on seals when success rate drops to ±40%; this is the first evidence of cessation of foraging at unproductive times by any predatory fish. at seal island, white shark predatory success is significantly lower at locations where frequency of predation is highest, suggesting that white sharks may launch suboptimal strikes in areas of greatest intraspecific competition; this is the first evidence of social influence on predation in any elasmobranch. idiosyncratic predatory behaviours and elevated success rates of known individual white sharks at seal island suggest some degree of trial-and-error learning. a hypothetical decision tree is proposed that models predatory behaviour of white sharks attacking cape fur seals at the surface.

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4

Troy, S. K., R. Mattlin, P. D. Shaughnessy, and P. S. Davie. "Morphology, age and survival of adult male New Zealand fur seals, Arctocephalus forsteri, in South Australia." Wildlife Research 26, no. 1 (1999): 21. http://dx.doi.org/10.1071/wr97103.

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Nineteen adult male New Zealand fur seals, Arctocephalus forsteri, were marked and measured at the start of the breeding seasons in November 1992 and 1993 at Cape Gantheaume, Kangaroo Island in South Australia. The age of each seal was estimated from the number of cementum layers in a post-canine tooth. The males that were attempting to hold territories were 7–15 years old and the heaviest was 160 kg. The mass of males could be predicted accurately from linear measurements and several predictive equations enable estimation of mass in the field. The mean annual survival rate for adult male New Zealand fur seals was 76%, which is higher than that in other fur seal species, perhaps reflecting the expanding nature of the A. forsteri population in Australia.

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5

VOORBERGEN, ANNE, WILLEM F. DE BOER, and LES G. UNDERHILL. "Natural and human-induced predation on Cape Cormorants at Dyer Island." Bird Conservation International 22, no. 1 (March 2012): 82–93. http://dx.doi.org/10.1017/s0959270912000032.

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SummaryTo develop conservation strategies for vulnerable seabird species that need attention, it is important to know which factors influence their breeding productivity. Predation of eggs and chicks can have large influences on seabird reproduction, especially when human disturbance facilitates predation. On Dyer Island, Kelp GullsLarus dominicanusprey on Cape CormorantPhalacrocorax capensiseggs and chicks, whereas Cape fur sealsArctocephalus pusillus pusillusprey on Cape Cormorant fledglings in the waters surrounding the island. Kelp Gulls were estimated to predate 3.8% of the total number of Cape Cormorant eggs and 2.0% of the chicks on the island. These percentages can be expressed as a loss of 4.8% of Cape Cormorant fledglings, which is low compared to the estimated 24.3% mortality of Cape Cormorant fledglings by Cape fur seal predation. Human disturbance facilitated Kelp Gull egg and chick predation and increased the mobbing of cormorant fledglings by Kelp Gulls. Cormorant egg predation by gulls was more frequently reported in the late afternoon. Seal predation was more abundant at the northern side of the island compared to the southern side, was recorded more frequently in the morning, and increased through the breeding season. The altered abundance and distribution of prey, the availability of suitable breeding habitat and mortality from avian cholera, have also influenced the Cape Cormorant’s population size. Hence, the possibility that Cape Cormorants may be locked in a predator-pit, where seals and gulls prevent the population from increasing in size, needs further attention.

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6

Mecenero, Silvia, Stephen P. Kirkman, and Jean-Paul Roux. "A refined fish consumption model for lactating Cape fur seals (Arctocephalus pusillus pusillus), based on scat analyses." ICES Journal of Marine Science 63, no. 8 (January 1, 2006): 1551–66. http://dx.doi.org/10.1016/j.icesjms.2006.06.005.

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Abstract A refined fish consumption model for lactating Cape fur seals in Namibia during the eight-month lactation period, which allows for spatio-temporal variation in the diet as determined by scat analyses, has been developed. Previous estimates of prey consumption by Cape fur seals have been based mostly on coarse diet composition models. Sensitivity analyses showed that the energetic requirement and mass of lactating females (bioenergetic variables), as well as the energetic density of prey (diet variable), contributed most to the uncertainty in consumption estimates. Uncertainty in the remaining input variables had minimal effects on the estimates of food consumption. The consumption of commercial prey (horse mackerel, hake and pelagic fish) was greatest by the colony at Cape Cross. The model estimated that a female of average mass 55 kg ingested, on average, 11% of her body mass per day. This model is easily applied to other age/sex classes of the seal population. It permits improvement of the estimates of prey consumption by seals, which are useful for assessing levels of competitive interactions between seals and fisheries or other predators, or the impacts of seals on prey species.

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7

Penry, Gwenith S., Ashwynn C. Baartman, and Marthán N. Bester. "Vagrant elephant seal predation on Cape fur seal pups, Plettenberg Bay, South Africa." Polar Biology 36, no. 9 (June 8, 2013): 1381–83. http://dx.doi.org/10.1007/s00300-013-1350-4.

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8

Kirkman, S. P., D. P. Costa, A. L. Harrison, P. G. H. Kotze, W. H. Oosthuizen, M. Weise, J. A. Botha, and J. P. Y. Arnould. "Dive behaviour and foraging effort of female Cape fur seals Arctocephalus pusillus pusillus." Royal Society Open Science 6, no. 10 (October 2019): 191369. http://dx.doi.org/10.1098/rsos.191369.

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While marine top predators can play a critical role in ecosystem structure and dynamics through their effects on prey populations, how the predators function in this role is often not well understood. In the Benguela region of southern Africa, the Cape fur seal ( Arctocephalus pusillus pusillus ) population constitutes the largest marine top predator biomass, but little is known of its foraging ecology other than its diet and some preliminary dive records. Dive information was obtained from 32 adult females instrumented with dive recorders at the Kleinsee colony (29°34.17′ S, 16°59.80′ E) in South Africa during 2006–2008. Most dives were in the depth range of epipelagic prey species (less than 50 m deep) and at night, reflecting the reliance of Cape fur seals on small, vertically migrating, schooling prey. However, most females also performed benthic dives, and benthic diving was prevalent in some individuals. Benthic diving was significantly associated with the frequency with which females exceeded their aerobic dive limit. The greater putative costs of benthic diving highlight the potential detrimental effects to Cape fur seals of well-documented changes in the availability of epipelagic prey species in the Benguela.

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9

Klein, Richard G., Kathryn Cruz-Uribe, David Halkett, Tim Hart, and John E. Parkington. "Paleoenvironmental and Human Behavioral Implications of the Boegoeberg 1 Late Pleistocene Hyena Den, Northern Cape Province, South Africa." Quaternary Research 52, no. 3 (November 1999): 393–403. http://dx.doi.org/10.1006/qres.1999.2068.

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Boegoeberg 1 (BOG1) is located on the Atlantic coast of South Africa, 850 km north of Cape Town. The site is a shallow rock shelter in the side of a sand-choked gully that was emptied by diamond miners. Abundant coprolites, chewed bones, and partially digested bones implicate hyenas as the bone accumulators. The location of the site, quantity of bones, and composition of the fauna imply it was a brown hyena nursery den. The abundance of Cape fur seal bones shows that the hyenas had ready access to the coast. Radiocarbon dates place the site before 37,000 14C yr ago, while the large average size of the black-backed jackals and the presence of extralimital ungulates imply cool, moist conditions, probably during the early part of the last glaciation (isotope stage 4 or stage 3 before 37,000 14C yr ago) or perhaps during one of the cooler phases (isotope substages 5d or 5b) within the last interglaciation. Comparisons of the BOG1 seal bones to those from regional Middle Stone Age (MSA) and Later Stone Age (LSA) archeological sites suggest (1) that hyena and human seal accumulations can be distinguished by a tendency for vertebrae to be much more common in a hyena accumulation and (2) that hyena and LSA accumulations can be distinguished by a tendency for hyena-accumulated seals to represent a much wider range of individual seal ages. Differences in the way hyenas and people dismember, transport, and consume seal carcasses probably explain the contrast in skeletal part representation, while differences in season of occupation explain the contrast in seal age representation. Like modern brown hyenas, the BOG1 hyenas probably occupied the coast year-round, while the LSA people focused their coastal visits on the August–October interval when nine-to-eleven-month-old seals were abundant. The MSA sample from Klasies River Mouth Cave 1 resembles BOG1 in seal age composition, suggesting that unlike LSA people, MSA people obtained seals more or less throughout the year.

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10

Rotherham, L. S., M. van der Merwe, M. N. Bester, and W. H. Oosthuizen. "Morphology and distribution of sweat glands in the Cape fur seal, Arctocephalus pusillus pusillus (Carnivora:Otariidae)." Australian Journal of Zoology 53, no. 5 (2005): 295. http://dx.doi.org/10.1071/zo04075.

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The present study examined whether sweat glands are present in the skin of the Cape fur seal, Arctocephalus pusillus pusillus. Sweat glands have an important role in thermoregulation; the presence or absence of sweat glands in the fur-covered and naked skin areas of the Cape fur seal was investigated using standard histological procedures and light and scanning electron microscopy. Sweat glands were present in both fur-covered and naked skin areas. The skin layers in the naked skin areas were thicker than those in the fur-covered areas, presumably to protect them against abrasions in the absence of hair. The density of apocrine sweat glands did not differ among the body regions; however, both apocrine and eccrine sweat glands were larger in naked skin areas than in fur-covered areas. This increased size of the glands suggests a more active role for the glands in the naked skin areas, and a higher heat-loss capability through evaporative cooling in these body regions.

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11

Rand, R. W. "Reproduction in the female Cape Fur Seal, Arctocephalus pusillus (Schreber)*." Proceedings of the Zoological Society of London 124, no. 4 (May 7, 2010): 717–40. http://dx.doi.org/10.1111/j.1469-7998.1955.tb07812.x.

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12

Torres, Daniel, Jorge Acevedo, Daniel E. Torres, Romeo Vargas, and Anelio Aguayo-Lobo. "Vagrant Subantarctic fur seal at Cape Shirreff, Livingston Island, Antarctica." Polar Biology 35, no. 3 (August 23, 2011): 469–73. http://dx.doi.org/10.1007/s00300-011-1082-2.

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13

Balmelli, M., and P. A. Wickens. "Estimates of daily ration for the South African (Cape) fur seal." South African Journal of Marine Science 14, no. 1 (June 1994): 151–57. http://dx.doi.org/10.2989/025776194784287111.

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14

De Vos, Alta, and M. Justin O'Riain. "Sharks shape the geometry of a selfish seal herd: experimental evidence from seal decoys." Biology Letters 6, no. 1 (September 30, 2009): 48–50. http://dx.doi.org/10.1098/rsbl.2009.0628.

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Many animals respond to predation risk by forming groups. Evolutionary explanations for group formation in previously ungrouped, but loosely associated prey have typically evoked the selfish herd hypothesis. However, despite over 600 studies across a diverse array of taxa, the critical assumptions of this hypothesis have remained collectively untested, owing to several confounding problems in real predator–prey systems. To solve this, we manipulated the domains of danger of Cape fur seal ( Arctocephalus pusillus pusillus ) decoys to provide evidence that a selfish reduction in a seals' domain of danger results in a proportional reduction in its predation risk from ambush shark attacks. This behaviour confers a survival advantage to individual seals within a group and explains the evolution of selfish herds in a prey species. These findings empirically elevate Hamilton's selfish herd hypothesis to more than a ‘theoretical curiosity’.

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15

Shaughnessy, Peter D., and Simon D. Goldsworthy. "Increasing abundance of pups of the long-nosed fur seal (Arctocephalus forsteri) on Kangaroo Island, South Australia, over 26 breeding seasons to 2013–14." Wildlife Research 42, no. 8 (2015): 619. http://dx.doi.org/10.1071/wr14209.

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Context Long-nosed (or New Zealand) fur seals breed on the southern coast of Australia, in New Zealand and on its subantarctic islands. They are recovering from over-harvesting that occurred in the early nineteenth century. Aims We estimated the rate of increase of the population at two colonies on Kangaroo Island, South Australia: Cape Gantheaume and Cape du Couedic. Methods From 1988–89 to 2013–14, pup abundance was estimated using a mark–resight procedure with multiple resights in large aggregations of pups and by direct counting in small aggregations. Key results At Cape Gantheaume, pup numbers increased by a factor of 10.7 from 457 to 5333 over 26 breeding seasons and the exponential rate of increase averaged 10.0% per annum (p.a.). Between 1988–89 and 1997–98, the population increased at 17.3% p.a., after which the increase was 7.2% p.a. At Cape du Couedic, pup numbers increased by a factor of 12.8 from 295 to 4070 over 21 breeding seasons at 11.4% p.a. Between 1988–89 and 1997–98, the increase averaged 14.2% p.a., after which it was 9.6% p.a. These increases have been accompanied by expansion in sub-colonies that existed in January 1989 and establishment of several new sub-colonies. Increases are likely to continue on Kangaroo Island. Conclusions There are few examples of increasing population levels for Australian native mammals and this is one of the best documented. It demonstrates that fur seal populations can recover from uncontrolled harvesting provided breeding habitat ashore is protected. Implications Fur seals interfere with fishers, disturb farmed tuna in aquaculture pens, and prey on little penguins.

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16

Botha, JA, SP Kirkman, JPY Arnould, AT Lombard, GJG Hofmeyr, MA Meÿer, PGH Kotze, and PA Pistorius. "Geographic variation in at-sea movements, habitat use and diving behaviour of female Cape fur seals." Marine Ecology Progress Series 649 (September 10, 2020): 201–18. http://dx.doi.org/10.3354/meps13446.

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Knowledge of animal foraging behaviour has implications for management and conservation. While Cape fur seals Arctocephalus pusillus pusillus comprise a major proportion of the southern African marine predator biomass, little is known about their at-sea movements. We investigated foraging distribution, habitat use and diving behaviour for 35 adult female Cape fur seals from 3 breeding colonies experiencing contrasting oceanographic regimes. Animals from Black Rocks, the smallest and eastern-most colony, undertook shorter foraging trips and utilised shallower waters over the shelf. In comparison, animals from the larger west coast colonies, at Kleinsee and False Bay, travelled further and utilised deeper shelf and shelf-slope waters. However, across colonies, females typically preferred depths of <500 m and slopes of <5°. Kleinsee and False Bay seals selected sea surface temperatures within the range typically preferred by pelagic prey species such as round herring, sardine and anchovy (14-19°C). Black Rocks individuals showed bimodal preferences for colder (16°C) and warmer waters (>22°C). Dive behaviour was similar between Kleinsee and False Bay individuals (unavailable from Black Rocks), with both pelagic and benthic foraging evident. Diel patterns were apparent at both sites, as dive depth and benthic diving increased significantly during daylight hours, likely reflecting vertical movements of prey species. We provide the first assessment of Cape fur seal movement behaviour for the South African component of the population. Observed geographic differences likely reflect the availability of suitable habitat but may also indicate differences in foraging strategies and density-dependent effects throughout the range of this species.

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17

Lyamin, O. I., and I. S. Chetyrbok. "Unilateral EEG activation during sleep in the Cape fur seal, Arctocehalus pusillus." Neuroscience Letters 143, no. 1-2 (August 1992): 263–66. http://dx.doi.org/10.1016/0304-3940(92)90279-g.

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18

Cressie, N. A. C., and P. D. Shaughnessy. "STATISTICAL METHODS FOR ESTIMATING NUMBERS OF CAPE FUR SEAL PUPS FROM AERIAL SURVEYS." Marine Mammal Science 3, no. 4 (October 1987): 297–307. http://dx.doi.org/10.1111/j.1748-7692.1987.tb00317.x.

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19

Arnould, J. P. Y., and R. M. Warneke. "Growth and condition in Australian fur seals (Arctocephalus pusillus doriferus) (Carnivora : Pinnipedia)." Australian Journal of Zoology 50, no. 1 (2002): 53. http://dx.doi.org/10.1071/zo01077.

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Mass and length growth models were determined for male (n = 69) and female (n = 163) Australian fur seals (Arctocephalus pusillus doriferus) collected at a breeding colony on Seal Rocks (38˚31′S, 145˚06′E), Bass Strait, in south-east Australia, between February and November during 1970–72. Growth was best described by the logistic model in males and the von Bertalanffy model in females. Asymptotic mass and length were 229 kg and 221 cm for males, and 85 kg and 163 cm for females. In all, 95% of asymptotic mass and length were attained by 11 years and 11 years, respectively, in males compared with 9 years and 5 years, respectively, in females. Males grew in length faster than females and experienced a growth spurt in mass coinciding with the onset of puberty (4–5 years). The onset of puberty in females occurs when approximately 86% of asymptotic length is attained. The rate of growth and sexual development in Australian fur seals is similar to (if not faster than) that in the conspecific Cape fur seal (A. p. pusillus), which inhabits the nutrient-rich Benguela current. This suggests that the low marine productivity of Bass Strait may not be cause of the slow rate of recovery of the Australian fur seal population following the severe over-exploitation of the commercial sealing era. Sternal blubber depth was positively correlated in adult animals with a body condition index derived from the residuals of the mass–length relationship (males: r2 = 0.38, n = 19, P < 0.001; females: r2 = 0.22, n = 92, P < 0.001), confirming the validity of using such indices on otariids. Sternal blubber depth varied significantly with season in adult animals. In males it was lowest in winter and increased during spring prior to the breeding season (r2 = 0.39, n = 19, P < 0.03) whereas in females it was greatest during winter (r2 = 0.05, n = 122, P< 0.05).

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20

Kirkman, SP, WH Oosthuizen, MA Meÿer, SM Seakamela, and LG Underhill. "Prioritising range-wide scientific monitoring of the Cape fur seal in southern Africa." African Journal of Marine Science 33, no. 3 (November 2011): 495–509. http://dx.doi.org/10.2989/1814232x.2011.637354.

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21

P. N. Odendaal, M. N. Bester, M. van der Merwe, and W. H. Oosthuizen. "Seasonal changes in the ovarian structure ofthe Cape fur seal, Arctocephalus pusillus pusillus." Australian Journal of Zoology 50, no. 5 (2002): 491. http://dx.doi.org/10.1071/zo01016.

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The annual reproductive cycle of the female Cape fur seal (Arctocephalus pusillus pusillus) was described by noting monthly gross changes in ovaries from 159 females, histological changes in 46 females and placental scars in 119 females. The size and weight of an ovary containing a corpus luteum was significantly greater than that of an ovary containing a corpus albicans for most of the year, the latter only approaching, or exceeding the former during the breeding season. Follicular activity initially increased in ovaries containing either a corpus luteum or a corpus albicans; however, it declined in the ovary containing a corpus luteum after implantation, while in that containing a corpus albicans it increased, reaching a maximum in December of 32.0 ± 10.08 follicles, averaging 5.41 ± 0.73 mm. The corpus luteum increased in size following ovulation, attaining a maximum size of 22.28 ± 3.38 mm in August (eight months after ovulation). Thereafter, it gradually decreased in size, generally becoming invisible to the naked eye by 30–32 months after ovulation. Luteal cells increased until seven months after ovulation, reaching a maximum size of 34.36 ± 1.26 μm before regressing, disappearing from the corpus luteum by 18 months after ovulation. Using placental scarring and CA counts in 119 females, a pregnancy rate of 77.4% was calculated, with 6.5% abortions and 16.1% non-implantations making up the remainder.

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22

Koep, K. S. C., L. C. Hoffman, L. M. T. Dicks, and E. Slinde. "Chemical composition of meat and blubber of the Cape fur seal (Arctocephalus pusillus pusillus)." Food Chemistry 100, no. 4 (January 2007): 1560–65. http://dx.doi.org/10.1016/j.foodchem.2005.12.035.

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23

Baylis, A. M. M., B. Page, K. Peters, R. McIntosh, J. Mckenzie, and S. Goldsworthy. "The ontogeny of diving behaviour in New Zealand fur seal pups (Arctocephalus forsteri)." Canadian Journal of Zoology 83, no. 9 (September 1, 2005): 1149–61. http://dx.doi.org/10.1139/z05-097.

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This study investigated the development of diving in 21 New Zealand fur seal pups, Arctocephalus forsteri (Lesson, 1828), prior to weaning at Cape Gantheaume, Kangaroo Island. Diving behaviour was examined using time–depth recorders, which were deployed during two time periods, 5 months prior to weaning (n = 6) and 2 months prior to weaning (n = 15). Scats were also examined to assess whether fur seal pups foraged prior to weaning. The maximum dive depth attained was 44 m, while the maximum dive duration was 3.3 min. Immediately prior to weaning, fur seal pups spent a greater proportion of their time diving at night, and concomitantly several measures of diving performance also increased. In general, pups dived successively deeper (6–44 m between June and September), and the average number of dives per day, dive frequency, and vertical distance travelled increased. Prey remains were present in approximately 30% of scats and indicated that some pups were foraging as early as June (5–6 months of age, approximately 4–5 months prior to weaning). Of the scats that contained prey remains, fish (South American pilchard, Sardinops sagax (Jenyns, 1842); Australian anchovy, Engraulis australis (White, 1790); and redbait, Emmelichthys nitidus Richardson, 1845) accounted for 43% of the prey items found, crustaceans accounted for 36%, and cephalopods (Gould's squid, Nototodarus gouldi (McCoy, 1888)) accounted for 20%.

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Butterworth, D. S., A. E. Punt, W. H. Oosthuizen, and P. A. Wickens. "The effects of future consumption by the Cape fur seal on catches and catch rates of the Cape hakes. 3. Modelling the dynamics of the Cape fur sealArctocephalus pusillus pusillus." South African Journal of Marine Science 16, no. 1 (December 1995): 161–83. http://dx.doi.org/10.2989/025776195784156511.

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25

Punt, A. E., J. H. M. David, and R. W. Leslie. "The effects of future consumption by the Cape fur seal on catches and catch rates of the Cape hakes. 2. Feeding and diet of the Cape fur sealArctocephalus pusillus pusillus." South African Journal of Marine Science 16, no. 1 (December 1995): 85–99. http://dx.doi.org/10.2989/025776195784156647.

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26

Stewardson, C. L. "THE IMPACT OF THE FUR SEAL INDUSTRY ON THE DISTRIBUTION AND ABUNDANCE OF CAPE FUR SEALSARCTOCEPHALUS PUSILLUS PUSILLUSON THE EASTERN CAPE COAST OF SOUTH AFRICA." Transactions of the Royal Society of South Africa 54, no. 2 (January 1999): 217–45. http://dx.doi.org/10.1080/00359199909520626.

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27

Oosthuizen, W. H., and E. H. Miller. "BACULAR AND TESTICULAR GROWTH AND ALLOMETRY IN THE CAPE FUR SEAL ARCTOCEPHALUS P. PUSILLUS (OTARIIDAE)." Marine Mammal Science 16, no. 1 (January 2000): 124–40. http://dx.doi.org/10.1111/j.1748-7692.2000.tb00908.x.

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Pharo, Elizabeth A., Kylie N. Cane, Julia McCoey, Ashley M. Buckle, W. H. Oosthuizen, Christophe Guinet, and John P. Y. Arnould. "A colostrum trypsin inhibitor gene expressed in the Cape fur seal mammary gland during lactation." Gene 578, no. 1 (March 2016): 7–16. http://dx.doi.org/10.1016/j.gene.2015.11.042.

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Punt, A. E., and D. S. Butterworth. "The effects of future consumption by the Cape fur seal on catches and catch rates of the Cape hakes. 4. Modelling the biological interaction between Cape fur sealsArctocephalus pusillus pusillusand the Cape hakesMerluccius capensisandM. paradoxus." South African Journal of Marine Science 16, no. 1 (December 1995): 255–85. http://dx.doi.org/10.2989/025776195784156494.

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Martin, R. A. "Natural mortality of puffadder shysharks due to Cape fur seals and black-backed kelp gulls at Seal Island, South Africa." Journal of Fish Biology 64, no. 3 (March 2004): 711–16. http://dx.doi.org/10.1111/j.1095-8649.2004.00339.x.

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Goldsworthy, SD, and PD Shaughnessy. "Breeding biology and haul-out pattern of the New Zealand fur seal, Arctopehalus forsteri, at Cape Gantheaume, South Australia." Wildlife Research 21, no. 3 (1994): 365. http://dx.doi.org/10.1071/wr9940365.

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New Zealand fur seals, Arctocephalus forsteri, breed at Cape Gantheaume (36�04'S,137�28'E), Kangaroo Island, South Australia, on broken rock platforms. In 1988-89, pups were born between late November and mid-January, 90% of them over 34 days between 3 December and 6 January. The median date of birth was 21 December. A re-analysis of data for this species from three breeding seasons at the Open Bay Islands (South Island, New Zealand, 43�52'S,l68�53'E) indicates that: (i) the breeding season at Cape Gantheaume occurs 5-12 days later than at the Open Bay Islands, (ii) the period containing 90% of births was the same duration for both populations, and (iii) the median date of birth spanned seven days in three seasons at the Open Bay Islands. In addition, the timing and duration of the pupping season varied within the Cape Gantheaume colony, it being later in recently colonised areas. We suggest that this pattern is a consequence of changes in the age distribution of females through the colony. The sex ratio of pups born in the colony over four breeding seasons did not differ significantly from 1:l. Females were mated on average 7.4 days after birth and left for sea 2.3 days later. The mean date of observed matings was 29 December; copulations lasted about 13 min. The operational sex ratio (OSR) in the colony was 8.6 females per territorial male (the maximum ratio of territorial males to pups was 1:16), which was within the range reported for other southern fur seal species. In two consecutive breeding seasons, the estimated fecundity rate of adult females averaged 67%. Non-breeding animals (sub-adult males, juveniles and yearlings) occurred in areas not occupied by breeding animals. The number of juveniles ashore increased after the breeding season, but no pattern was found for sub-adults and yearlings. Yearlings were uncommon in the colony at all times; it is suggested that they are mostly pelagic and do not moult in their second year.

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Shaughnessy, PD, SD Goldsworthy, and JA Libke. "Changes in the abundance of New Zealand fur seals, Arctocephalus forsteri, on Kangaroo Island, South Australia." Wildlife Research 22, no. 2 (1995): 201. http://dx.doi.org/10.1071/wr9950201.

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Kangaroo Island was an important seal-harvesting site during the early years of European colonisation of Australia. A recent survey of the New Zealand fur seal, Arctocephalus forsteri, in South and Western Australia indicates that Kangaroo I. is still an important centre for the species. In order to determine changes in the abundance of the population, numbers of pups were determined at four colonies on Kangaroo Island by mark-recapture in up to five breeding seasons from 1988-89 to 1992-93. Clipping was the preferred technique for mark-recapture estimation of pups because it was quick, easy and effective. Recaptures were conducted visually; they were repeated several times in each season to improve precision of the estimates. No pups were marked between recaptures in order to minimise disturbance. Assumptions made in estimating population size by the mark-recapture technique pertinent to this study are reviewed. Pup numbers increased at three colonies: at Cape Gantheaume, from 458 to 867 over five years (with exponential rate of increase r = 0.16, n = 5); at Nautilus North, from 182 to 376 over five years (at r = 0.19, n = 4); and at North Casuarina Islet, from 442 to 503 over four years (at r = 0.043, n = 2). Rates of increase in the first two colonies are similar to those at the most rapidly increasing fur seal populations in the Southern Hemisphere. The Kangaroo I. population is estimated to be 10000 animals in 1992-93. It is likely to be at the recolonisation phase of growth, with high rates of increase at individual colonies (or parts of colonies) resulting from local immigration. As space does not appear to be limiting expansion in these colonies, fur seal numbers may continue to increase there.

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Delling, Cora, Denny Böttcher, Vivien Schiffbauer, Andreas Bernhard, and Ronald Schmäschke. "First report of pulmonary cysticercosis caused by Taenia crassiceps in a Cape fur seal (Arctocephalus pusillus)." International Journal for Parasitology: Parasites and Wildlife 10 (December 2019): 83–86. http://dx.doi.org/10.1016/j.ijppaw.2019.07.006.

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Acevedo, Jorge, Anelio Aguayo-Lobo, and Daniel Torres. "Fetus presentation and time taken for parturition in Antarctic fur seal, Arctocephalus gazella, at Cape Shirreff, Antarctica." Polar Biology 31, no. 9 (May 22, 2008): 1137–41. http://dx.doi.org/10.1007/s00300-008-0446-8.

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Baylis, A. M. M., B. Page, and S. D. Goldsworthy. "Effect of seasonal changes in upwelling activity on the foraging locations of a wide-ranging central-place forager, the New Zealand fur seal." Canadian Journal of Zoology 86, no. 8 (August 2008): 774–89. http://dx.doi.org/10.1139/z08-055.

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Lactating New Zealand fur seals ( Arctocephalus forsteri (Lesson, 1828)) that breed at Cape Gantheaume, South Australia, experience broad-scale seasonal changes in ocean productivity. To assess how seasonal changes in ocean productivity influenced foraging behaviour, 18 lactating New Zealand fur seals were fitted with satellite transmitters and time–depth recorders (TDRs). Using temperature and depth data from TDRs, we used the presence of thermoclines as a surrogate measure of upwelling activity in continental-shelf waters. During the austral autumn 80% of lactating fur seals foraged on the continental shelf (114 ± 44 km from the colony), in a region associated with the Bonney upwelling. In contrast, during winter months seals predominantly foraged in oceanic waters (62%), in a region associated with the Subtropical Front (460 ± 138 km from the colony). Our results indicate that lactating New Zealand fur seals shift their foraging location from continental-shelf to oceanic waters in response to a seasonal decline in productivity over the continental shelf, attributed to the cessation of the Bonney upwelling. This study identified two regions used by lactating New Zealand fur seals: (1) a nearby and seasonally productive upwelling system and (2) a distant and permanent oceanic front.

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Hofmeyr, GJG, M. du Toit, and SP Kirkman. "Early post-release survival of stranded Cape fur seal pups at Black Rocks, Algoa Bay, South Africa." African Journal of Marine Science 33, no. 3 (November 2011): 463–68. http://dx.doi.org/10.2989/1814232x.2011.637352.

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Punt, A. E., and R. W. Leslie. "The effects of future consumption by the Cape fur seal on catches and catch rates of the Cape hakes. 1. Feeding and diet of the Cape hakesMerluccius capensisandM. paradoxus." South African Journal of Marine Science 16, no. 1 (December 1995): 37–55. http://dx.doi.org/10.2989/025776195784156539.

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de Bruyn, P. J. N., M. N. Bester, S. P. Kirkman, S. Mecenero, J. P. Roux, and N. T. W. Klages. "Cephalopod diet of the Cape fur seal,Arctocephalus pusillus pusillus, along the Namibian coast: variation due to location." African Zoology 40, no. 2 (October 2005): 261–70. http://dx.doi.org/10.1080/15627020.2005.11407325.

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Wilhelm, Margit R., Jean-Paul Roux, Coleen L. Moloney, and Astrid Jarre. "Data from fur seal scats reveal when Namibian Merluccius capensis are hatched and how fast they grow." ICES Journal of Marine Science 70, no. 7 (July 19, 2013): 1429–38. http://dx.doi.org/10.1093/icesjms/fst101.

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Abstract Wilhelm, M. R., Roux, J-P., Moloney, C. L., and Jarre, A. 2013. Data from fur seal scats reveal when Namibian Merluccius capensis are hatched and how fast they grow. – ICES Journal of Marine Science, 70: . Scat samples were collected regularly at several breeding colonies of Cape fur seals along the Namibian coast. Merluccius capensis otoliths were obtained from these samples, identified, and measured. Cohorts were easily distinguishable using otolith length measurements converted to fish total length. Growth rates of 2- to 21-month-old hake and hatch dates for each of 15 cohorts were estimated from September 1994 to October 2009 (1994–2008 cohorts) using a Schnute growth function and a non-linear mixed-effects model. The function describing growth of these young hake was length Lt (cm) at age t (years) Lt = 3.17 + (25.0 − 3.17) × [1 − e−0.665 × (t − 0.140)]/[1 − e−0.665 × (1.74–0.140)]. Cohort-specific random effects showed a population hatch date estimate of 31 July (austral winter), varying by 94 days among cohorts, from 31 May (1996 cohort) to 1 September (2004 cohort). The mean growth rate from ages 6 to 12 months was 1.26 cm month−1 for the population, ranging between 0.97 cm month−1 (1996 cohort) and 1.38 cm month−1 (2004 cohort). As this rate is almost double the previously estimated value, which is currently used in the stock assessment models, this result may have major implications for the current stock assessment results and the management of the stock. Re-examination of growth rates needs to be extended to older fish.

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Huisamen, J., SP Kirkman, CD van der Lingen, LH Watson, VG Cockcroft, R. Jewell, and PA Pistorius. "Diet of the Cape fur seal Arctocephalus pusillus pusillus at the Robberg Peninsula, Plettenberg Bay, and implications for local fisheries." African Journal of Marine Science 34, no. 3 (October 1, 2012): 431–41. http://dx.doi.org/10.2989/1814232x.2012.725524.

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Stewardson, C. L., M. N. Bester, and W. H. Oosthuizen. "Reproduction in the male Cape fur seal Arctocephalus pusillus pusillus: age at puberty and annual cycle of the testis." Journal of Zoology 246, no. 1 (September 1998): 63–74. http://dx.doi.org/10.1111/j.1469-7998.1998.tb00133.x.

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Stewardson, C. L., and M. Brett. "Aggressive behaviour of an adult male Cape fur seal (Arctocephalus pusillus pusillus) towards a great white shark (Carcharodon carcharias)." African Zoology 35, no. 1 (April 2000): 147–50. http://dx.doi.org/10.1080/15627020.2000.11407201.

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Skern-Mauritzen, M., S. P. Kirkman, E. Olsen, A. Bjørge, L. Drapeau, M. A. Meÿer, J.-P. Roux, S. Swanson, and W. H. Oosthuizen. "Do inter-colony differences in Cape fur seal foraging behaviour reflect large-scale changes in the northern Benguela ecosystem?" African Journal of Marine Science 31, no. 3 (December 2009): 399–408. http://dx.doi.org/10.2989/ajms.2009.31.3.12.1000.

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Kirkman, Steve P., D. Yemane, W. H. Oosthuizen, M. A. Meÿer, P. G. H. Kotze, H. Skrypzeck, F. Vaz Velho, and L. G. Underhill. "Spatio-temporal shifts of the dynamic Cape fur seal population in southern Africa, based on aerial censuses (1972-2009)." Marine Mammal Science 29, no. 3 (July 12, 2012): 497–524. http://dx.doi.org/10.1111/j.1748-7692.2012.00584.x.

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Hammerschlag, Neil, R. Aidan Martin, and Chris Fallows. "Effects of environmental conditions on predator–prey interactions between white sharks (Carcharodon carcharias) and Cape fur seals (Arctocephalus pusillus pusillus) at Seal Island, South Africa." Environmental Biology of Fishes 76, no. 2-4 (June 3, 2006): 341–50. http://dx.doi.org/10.1007/s10641-006-9038-z.

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Erdsack, Nicola, Guido Dehnhardt, and Wolf Hanke. "Coping with Heat: Function of The Natal Coat of Cape Fur Seal (Arctocephalus Pusillus Pusillus) Pups in Maintaining Core Body Temperature." PLoS ONE 8, no. 8 (August 8, 2013): e72081. http://dx.doi.org/10.1371/journal.pone.0072081.

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Matthee, C. A., F. Fourie, W. H. Oosthuizen, M. A. Meyër, and K. A. Tolley. "Mitochondrial DNA sequence data of the Cape fur seal (Arctocephalus pusillus pusillus) suggest that population numbers may be affected by climatic shifts." Marine Biology 148, no. 4 (October 25, 2005): 899–905. http://dx.doi.org/10.1007/s00227-005-0121-3.

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STEWARDSON, CAROLYN L., SUSAN HEMSLEY, MIKE A. MEYER, PAUL J. CANFIELD, and JOHN H. MAINDONALD. "Gross and microscopic visceral anatomy of the male Cape fur seal, Arctocephalus pusillus pusillus (Pinnipedia: Otariidae), with reference to organ size and growth." Journal of Anatomy 195, no. 2 (August 1999): 235–55. http://dx.doi.org/10.1046/j.1469-7580.1999.19520235.x.

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Wiesel, Ingrid. "Killing of Cape fur seal (Arctocephalus pusillus pusillus) pups by brown hyenas (Parahyaena brunnea) at mainland breeding colonies along the coastal Namib Desert." acta ethologica 13, no. 2 (June 8, 2010): 93–100. http://dx.doi.org/10.1007/s10211-010-0078-1.

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De Vos, Alta, M. Justin O'Riain, Michael A. Meyer, P. Gideon H. Kotze, and Alison A. Kock. "Behavior of Cape fur seals (Arctocephalus pusillus pusillus) in relation to temporal variation in predation risk by white sharks (Carcharodon carcharias)around a seal rookery in False Bay, South Africa." Marine Mammal Science 31, no. 3 (April 1, 2015): 1118–31. http://dx.doi.org/10.1111/mms.12208.

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