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Macquarie Island Elephant Seal Populations 1985 Onwards
This dataset contains the results from studies of the Elephant Seal (Mirounga leonina) at Macquarie Island. Results from branding surveys and photographs from 1985 onwards are reported. Numbers, life stage, sex, moult stage and migration patterns have been reported. Currently some 2000 pups a year are branded and the dataset includes birth dates, weights at birth and weaning and at 6, 12 and 18 months. This work was completed as part of ASAC (AAS) project 2265 (ASAC_2265). Objectives: To prepare research papers, from the extensive southern elephant seal dataset, that deal with key demographic parameters of the population such as size, age specific survivorship, fecundity, recruitment into the breeding population, age specific growth rates, and intrinsic rate of change of the population. In addition, later papers will investigate interannual variability in these parameters, how these relate to changing environmental conditions, and the effects of this on long term population fluctuations. To analyse and compare stable isotope ratios in the facial vibrissae of the seals and the hard parts of their prey to determine the geographical positions of the major foraging grounds of the seals. The isotope values will also allow the food webs, that support the seals, to be better defined. To measure the growth rates of elephant seal vibrissae so that changing isotope values, related to the prey and foraging areas, can be referred to particular foraging periods. Elephant seals characteristically have two separate periods of foraging: one in summer and one in winter. The positions of these episodes on a vibrissa can be identified once the growth rates of vibrissae are known. Taken from the progress report for the 2009-2010 season: Progress against objectives: 1. One paper published from the elephant seal dataset. Two papers also published during 2009/10 using data collected opportunistically during the life of this project. PhD student Andrea Walters continues to analyse the results of the whisker analyses. She has presented some of her results at the AMSA 2009 marine connectivity conference in Adelaide. An honours student has been engaged (start date March 2010) to analyse the squid component of the seals' diet. John van den Hoff spent the early summer at Macquarie Island finalising the collection of the demographic data. 2154 tag/brand resights were recorded. Collection of the data has continued on the island by Chris Oosthuizen, Ben Arthur and Iain Field since John returned to Australia. When those field workers return data collection will cease.
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Annual population estimates of Southern Elephant Seals at Macquarie Island from censuses made annually on October 15th.
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INDICATOR DEFINITION Count of all adult females, fully weaned pups and dead pups hauled out on, or close to, the day of maximum cow numbers, set for October 15. TYPE OF INDICATOR There are three types of indicators used in this report: 1.Describes the CONDITION of important elements of a system; 2.Show the extent of the major PRESSURES exerted on a system; 3.Determine RESPONSES to either condition or changes in the condition of a system. This indicator is one of: CONDITION RATIONALE FOR INDICATOR SELECTION Elephant seals from Macquarie Island are long distance foragers who can utilise the Southern Ocean both west as far as Heard Island and east as far as the Ross Sea. Thus their populations reflect foraging conditions across a vast area. The slow decline in their numbers (-2.3% annually from 1988-1993) suggests that their ocean foraging has been more difficult in recent decades. Furthermore, interactions with humans are negligible due to the absence of significant overlap in their diet with commercial fisheries. This suggests that changes in 'natural' ocean conditions may have altered aspects of prey availability. It is clear that seal numbers are changing in response to ocean conditions but at the moment these conditions cannot be specified. DESIGN AND STRATEGY FOR INDICATOR MONITORING PROGRAM Spatial Scale: Five beaches on Macquarie Island (lat54 degrees 37' 59.9' S, long 158 degrees 52' 59.9' E): North Head to Aurora Point; Aurora Point to Caroline Cove; Garden Cove to Sandy Bay; Sandy Bay to Waterfall Bay; Waterfall Bay to Hurd Point. Frequency: Annual census on 15th October Measurement Technique: Monitoring the Southern Elephant Seal population on Macquarie island requires a one day whole island adult female census on October 15 and a daily count of cow numbers, fully weaned pups and dead pups on the west and east isthmus beaches throughout October. Daily cow counts during October, along the isthmus beaches close to the Station, provide data to identify exactly the day of maximum numbers. The isthmus counts are recorded under the long-established (since 1950) harem names. Daily counts allow adjustment to the census totals if the day of maximum numbers of cows ashore happens to fall on either side of October 15. Personnel need to be dispersed around the island by October 15 so that all beaches are counted for seals on that day. This has been achieved successfully for the last 15 years. On the day of maximum haul out (around 15th October) the only Elephant seals present are cows, their young pups and adult males. The three classes can be readily distinguished and counted accurately. Lactating pups are not counted, their numbers are provided by the cow count on a 1:1 proportion. The combined count of cows, fully weaned pups and dead pups provides an index of pup production. The count of any group is made until there is agreement between counts to better than +/- 5%. Thus there is always a double count as a minimum; the number of counts can reach double figures when a large group is enumerated. The largest single group on Macquarie Island is that at West Razorback with greater than 1,000 cows; Multiple counts are always required there. RESEARCH ISSUES Much research has been done already to acquire demographic data so that population models can be produced. Thus there will be predicted population sizes for elephant seals on Macquarie Island in 2002 onwards and the annual censuses will allow these predictions to be tested against the actual numbers. The censuses are also a check on the population status of this endangered species. LINKS TO OTHER INDICATORS
Register of tagging data of Elephant Seals at Macquarie Island 1987-1991
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This is a scanned copy of a register of Elephant Seal tagging data from Macquarie Island from October 1987 to March 1991.
The Commercial Biology of the Elephant Seal (Mirounga leonina linn) on Macquarie Island - 1948
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Taken from the report prepared by R Kenny: In this report our comparatively brief knowledge of the Elephant Seal at Macquarie Island (based only on one year's observations) have been augmented by abstracting notes from "The Natural History of the Elephant Seal" by L. Harrison Matthews Discovery Reports, vol. 1 p. 233. 1929., based on observations at South Georgia. The Elephant Seal herds at the two islands are comparable - at South Georgia the animals had been overfished almost to the point of extinction by 1885, but were then not hunted for many years, and by 1929 had "increased in numbers till at the present time they are probably as numerous as ever", and are now fished under Government regulation to prevent extermination; the Macquarie Island herd has a similar history.
Elephant Seal Sightings, Heard Island (1949 to 1960)
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At Heard Island, Southern Indian Ocean, seals were branded between 1949-1953. Seal length was measured in feet and inches. Recaptures of seals were made up until 1955, and growth and age-specific survival was calculated.
Subset of data from the TAGS database of known age seals - Elephant Seals
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This database is a compendium of histories of known age seals (Southern elephant) from observations across the Southern Ocean but focussed on Macquarie Island, Marion Island, Heard Island, Mawson and the Vestfold Hills. At Macquarie Island 1000 seals were weighed per annum between 1993-2003 at birth and individually marked with two plastic flipper tags in the inter-digital webbing of their hind flippers. These tagged seals were weighed again at weaning, when length, girth, fat depth, and flipper measurements were made. Three weeks after weaning 2000 seals were permanently and individually marked by hot-iron branding. Recaptures and re-weighings of these known aged individuals were used to calculate growth and age-specific survival of the seals. Similar data were collected from elephant seals between 1950 and 1965 when seals were individually marked by hot-iron branding. Mark-recapture data from these cohorts were used to assess the demography of the declining population. Length and mass data were also collected for these cohorts and were used, for the first time, to assess the growth of individual seals without killing them. At Marion Island all the elephant seals have been individually marked with two plastic flipper tags in their rear flippers. Recaptures of these seals were used to compare survival at Marion and Macquarie Islands. At Heard Island, seals were branded between 1949-1953. Seal length was measured in feet and inches. Recaptures of seals were made up until 1955, and growth and age-specific survival was calculated. Survival data from Heard Island were compared with concurrent data from Macquarie Island. The database was held by the Australian Antarctic Data Centre, but was taken offline due to maintenance problems. A snapshot of the database was taken in January 2015 and stored in an access database and several csv files. This work was completed as part of ASAC project 90.
Post weaning dispersal and survival in the southern elephant seal
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The objectives for this project were: The project aims to quantify the patterns of dispersal and survival of newly weaned southern elephant seal pups to provide information on position at sea and foraging behaviour of the pups once they leave Macquarie Island, and to examine how this is related to position at sea and foraging behaviour in the second year. This information will be used to test the hypothesis that first year survival is a consequence of the young animals exploiting different foraging grounds to adults, and that fishing activity on the Campbell Plateau may be a contributing factor. In addition, stable isotope analysis and fatty acid signature analysis will be used to examine differences in foraging behaviour from animals while they are at sea. The raw data from this project is added to the long term database described by the metadata records 'Macquarie Island Elephant Seal Populations 1950-1965', and 'Macquarie Island Elephant Seal Populations 1985 Onwards'. This database has been taken offline, however. A snapshot of the database was taken in January, 1995, and is linked at the provided URL. For access, contact the Australian Antarctic Data Centre. A number of papers have been produced from this project. Some of these papers are included in the reference section below. The data collected for the database is as follows: Seal Number Status (new or resight) Date Location Age Class Status (cow, beachmaster, pregnant cow, dead etc) Sex Weight Length Size Back Fat Flipper Body Water Time Depth Recorder
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
Biology of the Sea Elephant (Elephant Seal), Heard Island, 1951
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This is a copy of a scanned document which contains a report, as well as tabulated data compiled by K. Brown on Sea Elephants (Elephant Seals) at Heard Island in 1951. The data are biological in nature, and deal with: Breeding Season 1951 Formation of the Harems Arrival of the Bulls Arrival of the Cows Birth of the Pups Lactation Moult Pup Mortality Fertilisation of the Cows Break up of the Harems Arrival of the Adolescents
Antarctic Fur Seal Populations on Heard Island Summer 1987-1988
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Abstract from ANARE Research Notes 72 The Antarctic fur seal Arctocephalus gazella has increased in numbers at Heard Island since the Australian National Antarctic Research Expeditions (ANARE) station was established in 1947. Increases have also been recorded at other breeding sites in the South Atlantic and South Indian Oceans this century, particularly at South Georgia. In the 1987-88 summer, fur seals at Heard Island were counted in several age and sex categories. The aims of the project were to determine the location of pupping sites, the extent of the pupping season and the size of the population, and to record the changes in numbers of animals ashore during the summer. Maps of the colonies and main haul-out areas, together with descriptions of census areas and tabulations of counts, provide a basis for future comparison. This dataset contains the results from surveys of Antarctic Fur Seals (Arctocephalus gazella) on Heard Island during the summer of 1987-1988. As well as habitat descriptions, age, sex, count of adults and pups were determined. The three major aims of the study include: to determine accurately the location of pupping sites; to determine the extent of the pupping season, the median date of birth and the number of pups born; and to census fur seals on as much of the island as possible in order to determine the number of animals ashore and to document changes in numbers during the summer. The results are listed in the document, which includes detailed tabulations of counts made at colonies and major haul-out sites on Macquarie Island during summer 1987-88, and descriptions and maps of these locations. Tagging, mainly of pups, was also undertaken, and a total of 234 pups, 8 under-yearlings, 9 yearlings, 2 juveniles and 1 sub-adult male were tagged. Counts at 3-day intervals (pups) were made between 25 November and 19 December 1987, and major censuses were made between 19 December 1987 and 25 February 1988. The fields in this dataset are: Locality Age Class Date Colony Bulls Cows Pups