John Arnould - Academia.edu (original) (raw)
Papers by John Arnould
Australian fur seal pup production: has its population reached the ceiling?
Repeated pup censuses for the Australian fur seal (Arctocephalus pusillus doriferus) have been pe... more Repeated pup censuses for the Australian fur seal (Arctocephalus pusillus doriferus) have been performed across the species’ range every five years since 2002 to monitor population trends. Live pup numbers were estimated at 20 pupping sites using one of the following methods: capture-mark-resight, direct count, or count from aerial photograph. From late December 2013 to February 2014, all known pupping sites for the species were visited. We identified the first overall drop in pup production since seal harvesting ceased in the early 1900s. We also report the first overall drop in pup production since exponential increase commenced in the 1980s, following legislative protection in 1975 that likely curtailed shooting by fishers. The 2013-14 estimate of live Australian fur seal pups (mean ± se = 15,063 ± 83) recorded a 6% per annum drop since 2007-08 (mean ± se = 21,882 ± 187). Previously, pup production had increased at 5% per year between 1986-87 and 2002-03 and 0.3% per year between...
Comparative Biochemistry and Physiology B-biochemistry & Molecular Biology, 2001
Chemical characterisation of the oligosaccharides in ž / hooded seal Cystophora cristata and Aust... more Chemical characterisation of the oligosaccharides in ž / hooded seal Cystophora cristata and Australian fur seal ž / Arctocephalus pusillus doriferus milk Abstract Ž . Carbohydrates were extracted from hooded seal milk, Crystophora cristata family Phocidae . Free oligosaccharides T. Urashima .
Marine Mammal Science, 2005
We estimated the number of live Australian fur seal pups using capture-markresights, direct groun... more We estimated the number of live Australian fur seal pups using capture-markresights, direct ground counts, or aerial photography at all breeding sites following the pupping season of November-December 2002. Pups were recorded at 17 locations; nine previously known colony sites, one newly recognized colony and seven haul-out sites where pups are occasionally born. In order of size, the colonies were Lady Julia Percy Island (5,899 pups), Seal Rocks (4,882), The Skerries (2,486), Judgment Rocks (2,427), Kanowna Island (2,301), Moriarty Rocks (1,007), Reid Rocks (384), West Moncoeur Island (257), and Tenth Island (124). The newly recognized site was Rag Island, in the Cliffy Group, where we recorded 30 pups. We also recorded pups at the following haul-out sites: Cape Bridge-water (7 pups), Bull Rock (7), Wright Rock (5), Twin Islet (1), The Friars (1), He des Phoques (1), and Montague Island (1). In total, we estimate there were 19,819 (SE = 163) live pups at the time of the counts. We discuss trends in pup numbers and derive current population estimates for the Australian fur seal.
Canadian Journal of Zoology-revue Canadienne De Zoologie, 2001
The dive behaviour, foraging locations, and colony-attendance patterns of female Australian fur s... more The dive behaviour, foraging locations, and colony-attendance patterns of female Australian fur seals (Arctocephalus pusillus doriferus) from Kanowna Island (39°10′ S, 146°18′ E) in Bass Strait, southeastern Australia, were determined throughout lactation during 1997-1999. Foraging-trip durations increased as lactation progressed, being shortest in summer (3.71 ± 0.24 days; mean ± 1 SE) and longest in winter (6.77 ± 0.57 days, P < 0.05), but maternalattendance periods did not differ in duration (1.70 ± 0.10 days, P > 0.5). Individual mean attendance periods and trip durations were positively correlated (r 2 = 0.21, P < 0.005). Diving commenced shortly after seals left the colony (2.6 ± 0.4 h), was continuous for long periods (up to 36 h), occurred mostly during daylight hours, and lacked regular diel variation in depth. The majority of dives (78%) were typically U-shaped and reached depths corresponding to the prevailing depths in Bass Strait (65-85 m), indicating that these animals forage mostly on the benthos of the shallow continental shelf in this region. Such behaviour is unusual for fur seals but is reminiscent of that of some sea lion species. Mean dive durations varied between 2.0 and 3.7 min (maximum 8.9 min) and the theoretical aerobic dive limit (3.91-4.26 min) was exceeded on 17.3% of dives. Dive frequency (8.3 ± 0.6/h) and the proportion of time at sea spent diving (40.7 ± 2.1%) were weakly negatively related to the duration of the foraging trip (r 2 = 0.07, P < 0.004, and r 2 = 0.13, P < 0.0001, respectively). Data from at-sea locations showed that lactating females forage almost exclusively within Bass Strait during all seasons.
![Research paper thumbnail of The Composition of Australian Fur Seal ([ITAL]Arctocephalus pusillus doriferus[/ITAL]) Milk throughout Lactation](https://attachments.academia-assets.com/48846979/thumbnails/1.jpg)
](Physiological and Biochemical Zoology, 1999
The proximate chemical composition of milk was determined throughout lactation in the Australian ... more The proximate chemical composition of milk was determined throughout lactation in the Australian fur seal (Arctocephalus pusillus doriferus Wood Jones), a temperate species with an 11mo lactation period typical of most temperate otariids. Average lipid and protein contents were 42% and 10%, respectively, which is similar to that recorded for the polar otariid species but higher than reported in other temperate, long-lactation species. Milk composition, however, varied substantially throughout lactation, with lipid content rising from 30% soon after parturition to 50% at 230 d postpartum before decreasing to 45% toward weaning. The trend in water content was opposite to that of lipid, while protein content increased only slightly during lactation from 10% to 12%. The peak in lipid content occurred at approximately 70% of the way through lactation, similar to that found in the Australian sea lion and several phocid seal species. Significant positive relationships were found between milk lipid content and both the duration of the preceding foraging trip and body mass. A highly significant and close correlation was found between milk water and lipid contents such that gross energy content may be accurately predicted from water content alone. Similar predictive equations have been found for several other otariid and phocid species, but these appear to differ between phylogenetic groups.
Marine Mammal Science, 2009
Journal of Zoology, 2002
Pre-weaning growth rates, body composition, milk consumption and mass gain ef®ciency were measure... more Pre-weaning growth rates, body composition, milk consumption and mass gain ef®ciency were measured in Australian fur seal Arctocephalus pusillus doriferus pups born in two consecutive breeding periods. Australian fur seals have the highest birth mass of any fur seal species (male 8.3 kg; female 7.2 kg). While their absolute pre-weaning growth rate (male 62 gÁday 71 ; female 53 gÁday 71 ) is similar to that of other temperate latitude fur seals, they have the longest birth-mass doubling time of any otariid species (134±136 days). Daily milk consumption increased from 400 gÁday 71 (5 MJÁday 71 ) after birth to 675 gÁday 71 (13.7 MJÁday 71 ) at age 210 day. However, mean mass-speci®c milk consumption (41 gÁkg 71 ) is substantially lower than in other otariid species (58±70 gÁkg 71 ) and, combined with a low mass gain ef®ciency (0.12 gÁg 71 ), contributes to the low mass-speci®c growth rates observed. There were no signi®cant differences in either absolute or mass-speci®c milk consumption between the sexes. Signi®cant differences, however, were found between the sexes in the body composition of pups with females generally having larger body lipid stores than males for any given mass. Peak milk yield by Australian fur seal females is estimated at 0.60 MJ Ç kg 70.75 , substantially less than in Antarctic fur seals. The low level of maternal energy transfer in Australian fur seals may re¯ect the relatively low marine productivity of their foraging areas.
Aquatic Conservation-marine and Freshwater Ecosystems, 2007
1.Numerous studies have determined the foraging areas of marine apex predators and investigated t... more 1.Numerous studies have determined the foraging areas of marine apex predators and investigated their relationship to oceanographic features. Most of these, however, have concentrated on surface-feeding seabirds or epipelagic-foraging marine mammals and there is little information on habitat selection in benthic divers.2.Satellite telemetry was used during the winters of 2001–2003 to determine the foraging areas of 48 female Australian fur seals (Arctocephalus pusillus doriferus) from four breeding sites in northern Bass Strait whose colonies together represent >80% of the total species population.3.All individuals foraged over the shallow continental shelf of Bass Strait supporting earlier studies that suggested the species is an exclusively benthic forager. Individual females showed a high degree of foraging site-fidelity and several foraging ‘hot spot’ areas could be identified.4.Analysis of habitat use indicated that individuals selected areas with depths of 60–80 m significantly more (λ=0.216, P<0.001) than any other bathymetric class. There was also evidence for foraging areas being influenced by SST, with individuals selecting regions of 16.0–16.8°C SST (λ=0.008, P<0.01), but not surface chlorophyll-a concentration (P>0.05).5.Temporal analysis of at-sea movements indicated, due to their primarily benthic foraging mode, the areas frequented by female Australian fur seals did not overlap substantially with areas targeted by commercial fisheries. An exception to this was in far eastern Bass Strait where the Otter Trawl component of the Commonwealth Trawl Sector is highly active over the continental shelf and encompasses the areas frequented by females from The Skerries colony. Copyright © 2008 John Wiley & Sons, Ltd.Numerous studies have determined the foraging areas of marine apex predators and investigated their relationship to oceanographic features. Most of these, however, have concentrated on surface-feeding seabirds or epipelagic-foraging marine mammals and there is little information on habitat selection in benthic divers.Satellite telemetry was used during the winters of 2001–2003 to determine the foraging areas of 48 female Australian fur seals (Arctocephalus pusillus doriferus) from four breeding sites in northern Bass Strait whose colonies together represent >80% of the total species population.All individuals foraged over the shallow continental shelf of Bass Strait supporting earlier studies that suggested the species is an exclusively benthic forager. Individual females showed a high degree of foraging site-fidelity and several foraging ‘hot spot’ areas could be identified.Analysis of habitat use indicated that individuals selected areas with depths of 60–80 m significantly more (λ=0.216, P<0.001) than any other bathymetric class. There was also evidence for foraging areas being influenced by SST, with individuals selecting regions of 16.0–16.8°C SST (λ=0.008, P<0.01), but not surface chlorophyll-a concentration (P>0.05).Temporal analysis of at-sea movements indicated, due to their primarily benthic foraging mode, the areas frequented by female Australian fur seals did not overlap substantially with areas targeted by commercial fisheries. An exception to this was in far eastern Bass Strait where the Otter Trawl component of the Commonwealth Trawl Sector is highly active over the continental shelf and encompasses the areas frequented by females from The Skerries colony.
Marine Ecology-progress Series, 2005
Marine top-predators such as marine mammals forage in a heterogeneous environment according to th... more Marine top-predators such as marine mammals forage in a heterogeneous environment according to their energetic requirements and to the variation in environmental characteristics. In this study, the behaviour of breeding females in 2 sympatric fur seal species, Antarctic fur seal Arctocephalus gazella and Subantarctic fur seal A. tropicalis, was investigated in relation to foraging effort. Foraging effort was hypothesised to be greater in Antarctic fur seal than in Subantarctic fur seal due to their shorter lactation period. Using satellite telemetry, time-depth recorders and satellite images of sea-surface temperature and chlorophyll a concentration, the foraging grounds, the at-sea activity budgets and the environmental features were determined for both species breeding on the Crozet Archipelago. Foraging cycle duration was similar for the 2 species, and the seals exhibited similar at-sea activity budgets. Only the proportion of time spent at sea was higher in Antarctic fur seals. Separate foraging areas were identified for the 2 species. Antarctic fur seal distribution was related to bathymetric features, while we did not find any direct relationship between chlorophyll a concentration and seal foraging areas. Our results suggest that Antarctic fur seals tend to respond to the higher needs of their pups by having a higher foraging efficiency and concentrating their foraging activity in the most productive areas.
Physiological and Biochemical Zoology, 2003
The fasting metabolism of 71-to 235-d-old subantarctic fur seal (Arctocephalus tropicalis) pups f... more The fasting metabolism of 71-to 235-d-old subantarctic fur seal (Arctocephalus tropicalis) pups from Amsterdam Island, southern Indian Ocean, was investigated during the long foraging trips of their mothers. Body lipid reserves were proportionally greater in female than male pups and higher in postmoult (37%) than premoult (10%) animals. The mass-specific rate of mass loss did not differ between the sexes but was lower than observed in other species. Daily mass loss was estimated to 56% fat, 10% protein, and 34% water. The rate of protein catabolism (15 g d Ϫ1 ) was negatively related to the size of initial lipid stores and accounted for 9% )%1ע( of total energy expenditure. However, body composition changes during the fast were not equal between the sexes, with females relying more on protein catabolism than males (11% and 5% of total energy expenditure, respectively). Energy expenditure (270 kJ kg Ϫ1 d Ϫ1 ) and metabolic water production (11.5 mL kg Ϫ1 d Ϫ1 ) rates are the lowest reported for an otariid species. These results suggest that subantarctic fur seal pups greatly reduce activity levels to lower energy expenditure in addition to adopting proteinsparing metabolic pathways in order to survive the extreme fasts they must endure on Amsterdam Island.
Marine Mammal Science, 2008
Marine Pollution Bulletin, 1997
The Antarctic marine environment has relatively few direct sources of man-made marine debris; how... more The Antarctic marine environment has relatively few direct sources of man-made marine debris; however, there is concern over the dangers posed to wildlife by increasing amounts of such debris. Between 1990 and 1995 beached debris was monitored at Bird Island, South Georgia. This was part of a programme developed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) to monitor compliance with waste disposal under MARPOL and the effectiveness of additional regulations to reduce entanglement of marine mammals and birds. Overall, and in all but one year, the highest incidence of debris occurred during the winter months when 75% of all items were collected. The most numerous category overall (76%), and in all samples since 1991, was pieces of synthetic line as used in the long-line fishery for the Patagonian toothfish Dissostichus eleginoides around South Georgia. Packaging bands (6%) and polythene bags (6%) were the next commonest items. There was a substantial increase in the number of items found ashore in 1995 which coincided with an apparent increase in the long-line fishing effort in the area. The increase in the incidence of synthetic line found ashore corresponds to the increase in the proportion of Antarctic fur seal Arctocephalus gazella entangled in this material at South Georgia in a parallel study. An increasing use of environmentally-aware scientific observers on all fishing vessels, leading to an increased awareness of existing legislation, should result in less man-made debris entering the marine environment in the area around South Georgia.
The diet of Antarctic fur seals Arctocephalus gazella during the breeding season at South Georgia
Polar Biology, 1996
... frequency of calculated standard lengths of Champsocephalus gunnari (Sept/Oct ft Nov/Dec .+I.... more ... frequency of calculated standard lengths of Champsocephalus gunnari (Sept/Oct ft Nov/Dec .+I.. Jan/Feb --++- Channichthys rhinoceratus (Sept-Nov -e-Dec-Feb --Q--), Electrona antarctica (Sept-Nov 4 Dec-Feb --O--) and Gymnoscopelus nicholsi (Dec + JanWeb --O--) taken ...
Marine Mammal Science, 2008
The vocal repertoire, structure, and behavioral context of airborne vocalizations produced by Aus... more The vocal repertoire, structure, and behavioral context of airborne vocalizations produced by Australian fur seals (Arctocephalus pusillus doriferus) are described using recordings made at a breeding colony on Kanowna Island, Bass Strait, Australia. The study identified six different call types: three produced by males (bark, guttural threat, and submissive call); five produced by females (bark, guttural threat, submissive call, growl, and pup attraction call) and the female attraction call produced by pups and yearlings. Vocalizations were compared according to age and sex classes. The overall structure and function of the pup attraction and female attraction call produced by females, yearlings, and pups, was similar. However, while similar in their overall appearance, certain call types have a lower fundamental frequency when compared with other fur seals. In addition, the male bark call alters in rate of production according to the context used, where calls are slower when males are stationary and advertising their territorial status and faster when males are involved in confrontations with other males or actively herding females. Further research is required to investigate changes in environmental conditions and 913 914 MARINE MAMMAL SCIENCE, VOL. 24, NO. 4, 2008 their effects on shaping the call structure and communication in Australian fur seals.
Australian fur seal pup production: has its population reached the ceiling?
Repeated pup censuses for the Australian fur seal (Arctocephalus pusillus doriferus) have been pe... more Repeated pup censuses for the Australian fur seal (Arctocephalus pusillus doriferus) have been performed across the species’ range every five years since 2002 to monitor population trends. Live pup numbers were estimated at 20 pupping sites using one of the following methods: capture-mark-resight, direct count, or count from aerial photograph. From late December 2013 to February 2014, all known pupping sites for the species were visited. We identified the first overall drop in pup production since seal harvesting ceased in the early 1900s. We also report the first overall drop in pup production since exponential increase commenced in the 1980s, following legislative protection in 1975 that likely curtailed shooting by fishers. The 2013-14 estimate of live Australian fur seal pups (mean ± se = 15,063 ± 83) recorded a 6% per annum drop since 2007-08 (mean ± se = 21,882 ± 187). Previously, pup production had increased at 5% per year between 1986-87 and 2002-03 and 0.3% per year between...
Comparative Biochemistry and Physiology B-biochemistry & Molecular Biology, 2001
Chemical characterisation of the oligosaccharides in ž / hooded seal Cystophora cristata and Aust... more Chemical characterisation of the oligosaccharides in ž / hooded seal Cystophora cristata and Australian fur seal ž / Arctocephalus pusillus doriferus milk Abstract Ž . Carbohydrates were extracted from hooded seal milk, Crystophora cristata family Phocidae . Free oligosaccharides T. Urashima .
Marine Mammal Science, 2005
We estimated the number of live Australian fur seal pups using capture-markresights, direct groun... more We estimated the number of live Australian fur seal pups using capture-markresights, direct ground counts, or aerial photography at all breeding sites following the pupping season of November-December 2002. Pups were recorded at 17 locations; nine previously known colony sites, one newly recognized colony and seven haul-out sites where pups are occasionally born. In order of size, the colonies were Lady Julia Percy Island (5,899 pups), Seal Rocks (4,882), The Skerries (2,486), Judgment Rocks (2,427), Kanowna Island (2,301), Moriarty Rocks (1,007), Reid Rocks (384), West Moncoeur Island (257), and Tenth Island (124). The newly recognized site was Rag Island, in the Cliffy Group, where we recorded 30 pups. We also recorded pups at the following haul-out sites: Cape Bridge-water (7 pups), Bull Rock (7), Wright Rock (5), Twin Islet (1), The Friars (1), He des Phoques (1), and Montague Island (1). In total, we estimate there were 19,819 (SE = 163) live pups at the time of the counts. We discuss trends in pup numbers and derive current population estimates for the Australian fur seal.
Canadian Journal of Zoology-revue Canadienne De Zoologie, 2001
The dive behaviour, foraging locations, and colony-attendance patterns of female Australian fur s... more The dive behaviour, foraging locations, and colony-attendance patterns of female Australian fur seals (Arctocephalus pusillus doriferus) from Kanowna Island (39°10′ S, 146°18′ E) in Bass Strait, southeastern Australia, were determined throughout lactation during 1997-1999. Foraging-trip durations increased as lactation progressed, being shortest in summer (3.71 ± 0.24 days; mean ± 1 SE) and longest in winter (6.77 ± 0.57 days, P < 0.05), but maternalattendance periods did not differ in duration (1.70 ± 0.10 days, P > 0.5). Individual mean attendance periods and trip durations were positively correlated (r 2 = 0.21, P < 0.005). Diving commenced shortly after seals left the colony (2.6 ± 0.4 h), was continuous for long periods (up to 36 h), occurred mostly during daylight hours, and lacked regular diel variation in depth. The majority of dives (78%) were typically U-shaped and reached depths corresponding to the prevailing depths in Bass Strait (65-85 m), indicating that these animals forage mostly on the benthos of the shallow continental shelf in this region. Such behaviour is unusual for fur seals but is reminiscent of that of some sea lion species. Mean dive durations varied between 2.0 and 3.7 min (maximum 8.9 min) and the theoretical aerobic dive limit (3.91-4.26 min) was exceeded on 17.3% of dives. Dive frequency (8.3 ± 0.6/h) and the proportion of time at sea spent diving (40.7 ± 2.1%) were weakly negatively related to the duration of the foraging trip (r 2 = 0.07, P < 0.004, and r 2 = 0.13, P < 0.0001, respectively). Data from at-sea locations showed that lactating females forage almost exclusively within Bass Strait during all seasons.
Physiological and Biochemical Zoology, 1999
The proximate chemical composition of milk was determined throughout lactation in the Australian ... more The proximate chemical composition of milk was determined throughout lactation in the Australian fur seal (Arctocephalus pusillus doriferus Wood Jones), a temperate species with an 11mo lactation period typical of most temperate otariids. Average lipid and protein contents were 42% and 10%, respectively, which is similar to that recorded for the polar otariid species but higher than reported in other temperate, long-lactation species. Milk composition, however, varied substantially throughout lactation, with lipid content rising from 30% soon after parturition to 50% at 230 d postpartum before decreasing to 45% toward weaning. The trend in water content was opposite to that of lipid, while protein content increased only slightly during lactation from 10% to 12%. The peak in lipid content occurred at approximately 70% of the way through lactation, similar to that found in the Australian sea lion and several phocid seal species. Significant positive relationships were found between milk lipid content and both the duration of the preceding foraging trip and body mass. A highly significant and close correlation was found between milk water and lipid contents such that gross energy content may be accurately predicted from water content alone. Similar predictive equations have been found for several other otariid and phocid species, but these appear to differ between phylogenetic groups.
Marine Mammal Science, 2009
Journal of Zoology, 2002
Pre-weaning growth rates, body composition, milk consumption and mass gain ef®ciency were measure... more Pre-weaning growth rates, body composition, milk consumption and mass gain ef®ciency were measured in Australian fur seal Arctocephalus pusillus doriferus pups born in two consecutive breeding periods. Australian fur seals have the highest birth mass of any fur seal species (male 8.3 kg; female 7.2 kg). While their absolute pre-weaning growth rate (male 62 gÁday 71 ; female 53 gÁday 71 ) is similar to that of other temperate latitude fur seals, they have the longest birth-mass doubling time of any otariid species (134±136 days). Daily milk consumption increased from 400 gÁday 71 (5 MJÁday 71 ) after birth to 675 gÁday 71 (13.7 MJÁday 71 ) at age 210 day. However, mean mass-speci®c milk consumption (41 gÁkg 71 ) is substantially lower than in other otariid species (58±70 gÁkg 71 ) and, combined with a low mass gain ef®ciency (0.12 gÁg 71 ), contributes to the low mass-speci®c growth rates observed. There were no signi®cant differences in either absolute or mass-speci®c milk consumption between the sexes. Signi®cant differences, however, were found between the sexes in the body composition of pups with females generally having larger body lipid stores than males for any given mass. Peak milk yield by Australian fur seal females is estimated at 0.60 MJ Ç kg 70.75 , substantially less than in Antarctic fur seals. The low level of maternal energy transfer in Australian fur seals may re¯ect the relatively low marine productivity of their foraging areas.
Aquatic Conservation-marine and Freshwater Ecosystems, 2007
1.Numerous studies have determined the foraging areas of marine apex predators and investigated t... more 1.Numerous studies have determined the foraging areas of marine apex predators and investigated their relationship to oceanographic features. Most of these, however, have concentrated on surface-feeding seabirds or epipelagic-foraging marine mammals and there is little information on habitat selection in benthic divers.2.Satellite telemetry was used during the winters of 2001–2003 to determine the foraging areas of 48 female Australian fur seals (Arctocephalus pusillus doriferus) from four breeding sites in northern Bass Strait whose colonies together represent >80% of the total species population.3.All individuals foraged over the shallow continental shelf of Bass Strait supporting earlier studies that suggested the species is an exclusively benthic forager. Individual females showed a high degree of foraging site-fidelity and several foraging ‘hot spot’ areas could be identified.4.Analysis of habitat use indicated that individuals selected areas with depths of 60–80 m significantly more (λ=0.216, P<0.001) than any other bathymetric class. There was also evidence for foraging areas being influenced by SST, with individuals selecting regions of 16.0–16.8°C SST (λ=0.008, P<0.01), but not surface chlorophyll-a concentration (P>0.05).5.Temporal analysis of at-sea movements indicated, due to their primarily benthic foraging mode, the areas frequented by female Australian fur seals did not overlap substantially with areas targeted by commercial fisheries. An exception to this was in far eastern Bass Strait where the Otter Trawl component of the Commonwealth Trawl Sector is highly active over the continental shelf and encompasses the areas frequented by females from The Skerries colony. Copyright © 2008 John Wiley & Sons, Ltd.Numerous studies have determined the foraging areas of marine apex predators and investigated their relationship to oceanographic features. Most of these, however, have concentrated on surface-feeding seabirds or epipelagic-foraging marine mammals and there is little information on habitat selection in benthic divers.Satellite telemetry was used during the winters of 2001–2003 to determine the foraging areas of 48 female Australian fur seals (Arctocephalus pusillus doriferus) from four breeding sites in northern Bass Strait whose colonies together represent >80% of the total species population.All individuals foraged over the shallow continental shelf of Bass Strait supporting earlier studies that suggested the species is an exclusively benthic forager. Individual females showed a high degree of foraging site-fidelity and several foraging ‘hot spot’ areas could be identified.Analysis of habitat use indicated that individuals selected areas with depths of 60–80 m significantly more (λ=0.216, P<0.001) than any other bathymetric class. There was also evidence for foraging areas being influenced by SST, with individuals selecting regions of 16.0–16.8°C SST (λ=0.008, P<0.01), but not surface chlorophyll-a concentration (P>0.05).Temporal analysis of at-sea movements indicated, due to their primarily benthic foraging mode, the areas frequented by female Australian fur seals did not overlap substantially with areas targeted by commercial fisheries. An exception to this was in far eastern Bass Strait where the Otter Trawl component of the Commonwealth Trawl Sector is highly active over the continental shelf and encompasses the areas frequented by females from The Skerries colony.
Marine Ecology-progress Series, 2005
Marine top-predators such as marine mammals forage in a heterogeneous environment according to th... more Marine top-predators such as marine mammals forage in a heterogeneous environment according to their energetic requirements and to the variation in environmental characteristics. In this study, the behaviour of breeding females in 2 sympatric fur seal species, Antarctic fur seal Arctocephalus gazella and Subantarctic fur seal A. tropicalis, was investigated in relation to foraging effort. Foraging effort was hypothesised to be greater in Antarctic fur seal than in Subantarctic fur seal due to their shorter lactation period. Using satellite telemetry, time-depth recorders and satellite images of sea-surface temperature and chlorophyll a concentration, the foraging grounds, the at-sea activity budgets and the environmental features were determined for both species breeding on the Crozet Archipelago. Foraging cycle duration was similar for the 2 species, and the seals exhibited similar at-sea activity budgets. Only the proportion of time spent at sea was higher in Antarctic fur seals. Separate foraging areas were identified for the 2 species. Antarctic fur seal distribution was related to bathymetric features, while we did not find any direct relationship between chlorophyll a concentration and seal foraging areas. Our results suggest that Antarctic fur seals tend to respond to the higher needs of their pups by having a higher foraging efficiency and concentrating their foraging activity in the most productive areas.
Physiological and Biochemical Zoology, 2003
The fasting metabolism of 71-to 235-d-old subantarctic fur seal (Arctocephalus tropicalis) pups f... more The fasting metabolism of 71-to 235-d-old subantarctic fur seal (Arctocephalus tropicalis) pups from Amsterdam Island, southern Indian Ocean, was investigated during the long foraging trips of their mothers. Body lipid reserves were proportionally greater in female than male pups and higher in postmoult (37%) than premoult (10%) animals. The mass-specific rate of mass loss did not differ between the sexes but was lower than observed in other species. Daily mass loss was estimated to 56% fat, 10% protein, and 34% water. The rate of protein catabolism (15 g d Ϫ1 ) was negatively related to the size of initial lipid stores and accounted for 9% )%1ע( of total energy expenditure. However, body composition changes during the fast were not equal between the sexes, with females relying more on protein catabolism than males (11% and 5% of total energy expenditure, respectively). Energy expenditure (270 kJ kg Ϫ1 d Ϫ1 ) and metabolic water production (11.5 mL kg Ϫ1 d Ϫ1 ) rates are the lowest reported for an otariid species. These results suggest that subantarctic fur seal pups greatly reduce activity levels to lower energy expenditure in addition to adopting proteinsparing metabolic pathways in order to survive the extreme fasts they must endure on Amsterdam Island.
Marine Mammal Science, 2008
Marine Pollution Bulletin, 1997
The Antarctic marine environment has relatively few direct sources of man-made marine debris; how... more The Antarctic marine environment has relatively few direct sources of man-made marine debris; however, there is concern over the dangers posed to wildlife by increasing amounts of such debris. Between 1990 and 1995 beached debris was monitored at Bird Island, South Georgia. This was part of a programme developed by the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) to monitor compliance with waste disposal under MARPOL and the effectiveness of additional regulations to reduce entanglement of marine mammals and birds. Overall, and in all but one year, the highest incidence of debris occurred during the winter months when 75% of all items were collected. The most numerous category overall (76%), and in all samples since 1991, was pieces of synthetic line as used in the long-line fishery for the Patagonian toothfish Dissostichus eleginoides around South Georgia. Packaging bands (6%) and polythene bags (6%) were the next commonest items. There was a substantial increase in the number of items found ashore in 1995 which coincided with an apparent increase in the long-line fishing effort in the area. The increase in the incidence of synthetic line found ashore corresponds to the increase in the proportion of Antarctic fur seal Arctocephalus gazella entangled in this material at South Georgia in a parallel study. An increasing use of environmentally-aware scientific observers on all fishing vessels, leading to an increased awareness of existing legislation, should result in less man-made debris entering the marine environment in the area around South Georgia.
The diet of Antarctic fur seals Arctocephalus gazella during the breeding season at South Georgia
Polar Biology, 1996
... frequency of calculated standard lengths of Champsocephalus gunnari (Sept/Oct ft Nov/Dec .+I.... more ... frequency of calculated standard lengths of Champsocephalus gunnari (Sept/Oct ft Nov/Dec .+I.. Jan/Feb --++- Channichthys rhinoceratus (Sept-Nov -e-Dec-Feb --Q--), Electrona antarctica (Sept-Nov 4 Dec-Feb --O--) and Gymnoscopelus nicholsi (Dec + JanWeb --O--) taken ...
Marine Mammal Science, 2008
The vocal repertoire, structure, and behavioral context of airborne vocalizations produced by Aus... more The vocal repertoire, structure, and behavioral context of airborne vocalizations produced by Australian fur seals (Arctocephalus pusillus doriferus) are described using recordings made at a breeding colony on Kanowna Island, Bass Strait, Australia. The study identified six different call types: three produced by males (bark, guttural threat, and submissive call); five produced by females (bark, guttural threat, submissive call, growl, and pup attraction call) and the female attraction call produced by pups and yearlings. Vocalizations were compared according to age and sex classes. The overall structure and function of the pup attraction and female attraction call produced by females, yearlings, and pups, was similar. However, while similar in their overall appearance, certain call types have a lower fundamental frequency when compared with other fur seals. In addition, the male bark call alters in rate of production according to the context used, where calls are slower when males are stationary and advertising their territorial status and faster when males are involved in confrontations with other males or actively herding females. Further research is required to investigate changes in environmental conditions and 913 914 MARINE MAMMAL SCIENCE, VOL. 24, NO. 4, 2008 their effects on shaping the call structure and communication in Australian fur seals.