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Foraging ecology of fur seals at Iles Kerguelen
Public summary for project 2128: The aim of this study is to relate the foraging behaviour of Antarctic fur seals breeding on the Kerguelen Plateau at Iles Kerguelen and Heard Island, to the distribution of prey species at sea. Specifically this project seeks to examine the relationship between predators and prey, and how their locations at sea vary according to the position of major productive zones, such as the Antarctic Polar Frontal Zone. This project will provide important data on the relationship between predators and their prey and the developing commercial fisheries in the region. These data are central to improved conservation and management of marine resources on the Kerguelen Plateau. Variations made to the work plan The original comparative aspects of the program planned for the 1999/00 season, where fur seals from Iles Kerguelen and Heard Island were to be satellite tracked simultaneously could not be undertaken because of original 1999/00 field season to Heard Island was re-scheduled to 2000/01. Fortunately the project collaborator Dr Christophe Guinet (French CEBC-CNRS) agreed to extend the work program at Iles Kerguelen another season, and the comparative and integrated fur seal-prey-fisheries study over the Kerguelen Plateau was undertaken the following season (2000/01). Details of this study are presented in ASAC project 1251 (CI - Goldsworthy)and 1085 (CI-Robertson). Significant findings: The distribution of the foraging activity of Antarctic fur seal females was investigated at Cap Noir (49 degrees 07 S, 70 degrees 45E), Kerguelen Island in February 1998. Eleven females were fitted with a satellite transmitter and Time Depth recorder. The two sets of data were combined to locate spatially the diving activity of the seals. The fish component of the fur seal diet was determined by the occurrence of otolotihs found in 55 scats collected during the study period at the breeding colony. Oceanographic parameters were obtained simultaneously through direct sampling and satellite imagery. The mesopelagic fish community was sampled on 20 stations along four transects where epipelagic trawls were conducted at night at 50 meters of depth. We then investigated, using geographic information systems, the relationship between the spatial distribution of the diving activity of the fur seals and oceanographic factors that included sea surface temperature, surface chlorophyll concentration, prey distribution and bathymetry obtained at the same spatio-temporal scale as the spatial distribution of the diving activity of our study animals. An inverse relationship was found between the main fish species preyed by fur seal and those sampled in trawl nets. However, the diving activity of Antarctic fur seal females was found to be significantly related to oceanographic conditions, fish-prey distribution and to the distance from the colony but these relationships changed with the spatial scale investigated. A probabilistic model of the Kerguelen Plateau was developed that predicted where females should concentrate their foraging activity according to the oceanographic conditions of the year, and the locations of their breeding colonies. Maternal allocation in growth of the pup was measured in Antarctic fur seals (Arctocephalus gazella) at Iles Kerguelen during the 1997 austral summer. Absolute mass gain of pups following a maternal foraging trip was independent of the sex of the pup but was positively related to the foraging trip duration and to maternal length. However, daily mass gain, i.e. the absolute mass gain of the pup divided by the foraging trip duration, decreased with increasing foraging trip duration but increased with maternal length. While fasting, the daily mass loss of the pup was related to the sex of the pup and initial body mass, with both heavier pups and female pups losing more mass per day than lighter pups and male pups. The mass specific rate of mass loss was significantly higher in female pups than in male
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Diet and Foraging Area of Antarctic Fur Seals at Heard Island
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Antarctic Fur Seals from Heard Island fed mainly on fish, but the prey species changed both seasonally and inter-annually. The majority of prey were pelagic myctophids characteristic of deep oceanic water, and were generally taken in autumn and winter. The only other fish taken in significant numbers was Champsocephalus gunnari which was mostly taken from late winter through early autumn when it was co-dominant in the diet with the Krefftichthys anderssoni. Males and females foraged in different localities and in different parts of the water column. Males foraged mainly to the south of Heard Island in winter usually diving deep by day, feeding on scattering layers. In summer males also fed on the shelf, presumably to the north and east of Heard Island on K. anderssoni at shallow depths primarily at night. Although diet studies provided little evidence of feeding on crustaceans, diving data indicate that some males may travel to Antarctic waters in winter to feed on krill. The fields in this dataset are: Months Species Scats Time foraging Number of Dives Time Submerged (minutes) Mean Dive Duration (minutes) Maximum Depth (metres)
Weddell Seals of the Vestfold Hills Antarctica
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This dataset contains the results from studies of the Weddell Seal (Lepotonychotes weddellii) in the Vestfold Hills region, Antarctica. Results from tagging surveys, photographs and aerial surveys since 1973 are reported. Numbers, life stage, sex, moult stage and migration patterns have been reported. Fecal samples have been collected and from the otoliths, vertebrae, cephalopod beaks and crustacean remains, the diets and feeding habits have been investigated. Many of the results are reported in the document. This metadata record encompasses ASAC projects 89, 95 and 199 (ASAC_89, ASAC_95, ASAC_199).
Distribution of foraging effort of Antarctic fur seals in relation to oceanographic features around Heard and Kerguelen Islands
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Metadata record for data from ASAC Project 1251 See the link below for public details on this project. ---- Public Summary from Project ---- The aim of this study is to develop spatial GIS models of fur seal foraging density over the Kerguelen Plateau that will enable a rapid assessment method for identifying areas of high conservation value for Marine Protected Area planning and management. These models will be based on data on fur seal foraging densities in the HIMI region, and oceanographic data on bathymetry, sea-surface temperature and ocean colour (primary productivity). From the abstract of the referenced paper: We investigated the spatial and temporal distribution of foraging effort by lactating Antarctic fur seals Arctocephalus gazella at Heard Island using satellite telemetry and time-depth recorders. Two principal diving types were identified: 'deep' dives averaging 48.6 m, and 'shallow' dives averaging 8.6 m. Discriminant function analyses were used to assign dives based on their depth and duration. Generalised linear mixed-effects models of night dives (greater than 80% of all dives) indicated both spatial and temporal effects on the distribution of deep and shallow dives. Deep dives were more common in the deeper shelf waters of the Kerguelen Plateau, and these dives predominantly occurred after sunset and before sunrise. In contrast, shallow dives were more common in slope waters on the southeastern margin of the Kerguelen Plateau in the hours either side of local midnight. We suggest that these 2 distinct diving types reflect the targeting of channichthyid (deep dives) and myctophid (shallow dives ) fish, and are indicative of spatial and temporal differences in the availability of these 2 important prey groups. We also identified 3 distinct behavioural dive groups (based on multidimensional scaling of 19 diving and foraging trip parameters) that also differed in their spatial distribution and in their relative importance of deep and shallow dives. The present study provides some of the first evidence that diving strategies are not only influenced by where foraging takes place, but also when. The fields in the campaign_41_tracks.csv file are: campaign_id (the campaign identifier: aadc_campaign_41) animal_id (the identifier of the individual animal) scientific_name (scientific name: Arctocephalus gazella) ptt_id (the identifier of the PTT device on the animal. Note that individual PTT devices were deployed multiple times on different animals) deployment_location (the location of deployment: Spit Bay, Heard Island)) deployment_longitude (longitude of deployment location) deployment_latitude (latitude of deployment location) observation_date (the date of observation, in ISO8601 format yyyy-mm-ddTHH:MM:SSZ. This information is also separated into the year, month, day, etc components) observation_date_year (the year of the observation date) observation_date_month (the month of the observation date) observation_date_day (the day of the observation date) observation_date_hour (the hour of the observation date) observation_date_minute (the minute of the observation date) observation_date_second (the second of the observation date) observation_date_time_zone (the time zone of the observation date) latitude (the latitude of the observed position, in decimal degrees) longitude (the longitude of the observed position, in decimal degrees) location_class (the Argos location class of the observed position: one of (in increasing order of accuracy) B,A,0,1,2,3) trip (the trip number of the animal) at_sea (whether the observed position occurred at sea) complete (whether the complete trip was recorded) The fields in the campaign_41_supplementary.csv file are: animal_id (the identifier of the individual animal) behavioural_dive_group (1 = deep; 2 = shallow-active; 3 = shallow) departure_date (date of departure of the animal on the trip) departure_mass (mass of the animal on departure, in kg) standard_length (standard length of the
Winter foraging ranges of Weddell seals: a pilot study to assess their role in the winter sea-ice zone and their potential as ocean sampling platforms
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Metadata record for data from ASAC Project 2695 See the link below for public details on this project. Variations in the winter extent of sea ice are thought to have profound effects on biological productivity, such as algal growth and the reproduction of Antarctic krill, with subsequent flow-on effects through the food web. This pilot study aims to measure the winter foraging patterns of Weddell seals (Leptonychotes weddellii) as a first step in investigating their role in the winter sea-ice zone. Our specific objectives are to: Obtain satellite tracks from a sample of adult female Weddell seals Collect diving behaviour (dive depth, duration and frequency) from a sub-set of these seals Collect high precision water temperature data from a subset of these seals These data will enable us to assess the feasibility of including Weddell seals as a candidate species in a long-term study of winter sea-ice and predator performance. This project has now been merged into project number 2794 (ASAC_2794). It also contains data collected as part of project 1171 (ASAC_1171). The download file contains 13 Access Databases containing data from this project. An excel spreadsheet summarising the databases is also included. The data have also been loaded into the Australian Antarctic Data Centre's ARGOS tracking database. The database can be accessed at the provided URL.
Ecology of Southern Elephant Seals
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Metadata record for data from ASAC Project 257 See the link below for public details on this project. From the abstracts of some of the referenced papers: Anatomical and physiological studies of southern elephant seals (Mirounga leonina), particularly in the post-natal period, raise questions of relative musculature growth, control of metabolism, circulation and temperature regulation, which could be important in our understanding of these processes in mammals and of their contribution to adaptation to environmental extremes. The diving behaviour of 14 adult southern elephant seals was investigated using time depth recorders. Each of the seals performed some dives that were longer than its theoretical aerobic dive limit. Forty-four percent of all dives made by post-moult females exceeded the calculated limit compared with 7% of those made by postbreeding females and less than 1% of those made by adult males. The extended dives displayed characteristics that suggested they were predominantly foraging dives, although some were apparently rest dives. Dives longer than the calculated aerobic limits often occurred in bouts; the longest consisted of 63 consecutive dives and lasted 2 days. Postmoult females performed longer bouts of extended dives than postbreeding females. Extended surface periods (longer than 30 min) were not related to the occurrence of extended dives or bouts of extended dives. The possible physiological mechanisms that permit such prolonged continuous dives are discussed. Southern elephant seals may increase the aerobic capacity of dives by lowering their metabolism to approximately 40% of the resting metabolic rate on long dives. There is substantial interseal variability in the methods used to cope with long dives. Some animals appear to use phsyiological strategies that allow them to prolong the time available to them at the bottom of a dive, while others use alternative strategies that may limit the time available at the bottom of their dives. Fourteen time-depth-temperature recorders were recovered from adult southern elephant seals (Mirounga leonina) returning to Macqaurie Island to breed or moult. The resulting temperature/depth profiles indicated that all four males spent most of their time in waters lying over the Antarctic Continental Shelf, whereas only one of the ten females spent any time there. Five of the females foraged just off the Antarctic Continental Shelf, and the other five remained near the Antarctic Polar Front. 1) Mark-resight data were analysed for thirteen cohorts from a declining population of southern elephant seals branded at Macquarie Island between 1951 and 1965. 2) First year survival was essential stable during the 1950s at about 46% for females and 42% for males. There was a dramatic fall in first year survival during the 1960s, declinging to less than 2% for both sexes in 1965. Post-year-1 survival did not change between the 1950s and the 1960s. 3) Comparisons with a stable population of southern elephant seals at South Georgia indicated that both first year and adult survival were lower in the Macquarie Island population. There were no changes in the age at first breeding of the Macquarie Island seals during the study, but this was on average 1 year later than at South Georgia. 4) It is hypothesised that the current decline in elephant seal numbers at several of their major breeding islands is due to the populations returning to pre-sealing levels after they had risen to abnormally high levels with the end of commercial exploitation early this century. 5) Possible tests of the hypothesis include studying the diet and foraging behaviour of southern elephant seals to gain an understanding of the predator-prey relationships, continuing to census the Macquarie Island population to determine if the population levels out at around the estimated pre-sealing levels, and monitoring northern elephant seal populations which were also severely exploited but are currently increasing
Winter Foraging Locations Of Southern Ocean Predators - sub-Antarctic islands
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Metadata record for data expected from ASAC Project 2940 See the link below for public details on this project. Public: The extent of Antarctic winter sea-ice influences all aspects of the Antarctic marine food-web. We will use natural variations in inter-annual ice extent, to assess how a key component of that ecosystem, the predators, use the sea ice zone. Core foraging areas and dietary signals for a key Antarctic predator (Antarctic fur seal) will be identified. We will use newly developed, technology to track the animals, and stable isotopes to examine tropic linkages. Combined with satellite-derived sea-ice data, this will lead to the development of a model to predict how changing sea-ice patterns will influence Antarctic marine predator communities. Project Objectives: 1. Use large samples of newly-developed (and tested) animal-borne miniature geolocating light level recorders to population level information on the spatial extent of movements of Antarctic fur seals, thereby quantifying the extent of the use of the winter pack-ice and associated waters by these abundant predators. 2. To quantify how changes in winter ice extent influence the location of core foraging areas for this species. 3. To develop models to investigate how changing ice conditions in the future will influence the movements of this species and to examine a range of climate-change scenarios. Taken from the 2007-2008 Progress Report: No field work was conducted at Macquarie Island in the last 12 months. This was due to the decision by the state government to not issue permits for the work. With the help of our colleagues from BAS we did however manage to deploy 20 GLS light loggers on Antarctic fur seals at South Georgia. Taken from the 2008-2009 Progress Report: Objective 1 has been revised to the study of Antarctic fur seals only (see below). Research is progressing well with 78 animals tracked in 2008 and a further 80 expected in 2009. Objectives 2 and 3 will follow once field data is available for both years (May 2010). Isotopic analysis of blood and whisker samples for the 2008 season will commence in May 2009 once samples have been received. Taken from the 2010-2011 Progress Report: Public summary of the season progress: This study has quantified the response of the Antarctic fur seal (Arctocephalus gazella) to inter-annual variation in oceanographic and winter ice conditions. We have measured the winter spatial foraging patterns of 66 adult females from three circum-Antarctic populations over two years (2008, 2009) during 114 trips to sea, while simultaneously recording in situ water temperature. Stable isotope analysis of fur seal blood and whisker samples indicates that adult females feed on a range of lower (krill) to higher (fish and squid) trophic levels across their winter range. Broad-scale habitat preferences across the range of the species indicate the importance of shelf, ice edge, frontal and oceanic and continental upwelling features in determining winter foraging movements.
Foraging Ecology of Gentoo Penguins
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Gentoo penguins are the least numerous of the penguins breeding at Macquarie Island, and the only species to rear two chicks. This project examined the interactions between diving behaviour, diet and reproductive strategy. Data were collected on Time Depth Recorders (TDRs), and stored in hexadecimal format. Hexadecimal files can be read using 'Instrument Helper', a free download from Wildlife Computers (see the url given below).
Shallow Coastal Marine Fauna of the Vestfold Hills and Rauer Island Antarctica
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This dataset is a description of the shallow coastal marine fauna found in the Vestfold Hills and Rauer Island area, Antarctica. The results are from various surveys in this region over a 12 month period in 1981-82, and a full listing of species (with photographs) is given in the documentation. It includes benthic, pelagic and planktonic organisms of the coast as well as those that inhabit the ice-water interface.
NZ-Australia Antarctic Ecosystems Voyage to the Ross Sea - Marine Mammal Data
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This metadata record is a parent for all data on Antarctic blue whales collected during the 2015 New Zealand-Australia Antarctic Ecosystems Voyage. Description of specific data sets can be found in the Voyage Science Plan and within child datasets.
Kerguelen Axis salps and Thysanoessa macrura
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Zooplankton were collected with a Rectangular Midwater Trawl (RMT 8+1 net) from 37 sampling sites on and near the Southern Kerguelen Plateau. The contents of each net were preserved in 5% buffered formaldehyde. This dataset covers the counts of the contents of the RMT8 net and includes the abundances for the euphausiid Thysanoessa macrura and the salp Salpa thompsoni. The contents were identified and counted under a Leica M165C stereo-microscope. A flow meter attached to the mouth of the RMT 8 was used to record the volume of seawater passing through the net. The count for Thysanoessa macrura includes the total of all developmental stages. For the salps abundances are shown for the 2 developmental phases - solitary individuals and aggregates.