Description: Evaluating how populations are connected by migration is important for understanding species resilience because gene flow can facilitate recovery from demographic declines. We therefore investigated the extent to which migration may have contributed to the global recovery of the Antarctic fur seal ( Arctocephalus gazella ), a circumpolar distributed marine mammal that was brought to the brink of extinction by the sealing industry in the eighteenth and nineteenth centuries. It is widely believed that animals emigrating from South Georgia, where a relict population escaped sealing, contributed to the re-establishment of formerly occupied breeding colonies across the geographical range of the species. To investigate this, we interrogated a genetic polymorphism (S291F) in the melanocortin 1 receptor gene, which is responsible for a cream-coloured phenotype that is relatively abundant at South Georgia and which appears to have recently spread to localities as far afield as Marion Island in the sub-Antarctic Indian Ocean. By sequencing a short region of this gene in 1492 pups from eight breeding colonies, we showed that S291F frequency rapidly declines with increasing geographical distance from South Georgia, consistent with locally restricted gene flow from South Georgia mainly to the South Shetland Islands and Bouvetøya. The S291F allele was not detected farther afield, suggesting that although emigrants from South Georgia may have been locally important, they are unlikely to have played a major role in the recovery of geographically more distant populations.

Description: The migratory behaviour of adult male southern elephant seals, Mirounga leonina, from King George Island was studied in relation to sea ice coverage. Fourteen animals were immobilzed and fitted with satellite linked transmitters (Telonics/Wildlife Computers, USA) after the annual moult at their southernmost breeding colony at Stranger Point, King George Island, South Shetland Islands, from March to May 2000. The seals were tracked by Service ARGOS (Toulouse/France) for up to 12 months until March 2001. Daily data of sea ice coverage were derived from the Special Sensor Microwave/Imager (SSM/I) of the Defence Meteorological Satellite Program (DMSP).The bulls moved south-eastward along the shelf margin east of the Antarctic Peninsula reaching their southernmost locations in the interior pack ice of the Weddell Sea in May 2000.Here they concentrated their foraging close to the northern sill of the Filchner Trough. This region corresponds to a divergence of the Antarctic Coastal Current which forms the southern limb of the Weddell Gyre. Upwelling in this area might cause vertical transport of organic material which correlates with increased prey availability for top predators through food web linkages. In August 2000 the remaining bulls with functional transmitters returned northwards to their breeding sites, mainly King George Island.The migration routes of the bulls differ considerably from those of cows and weaned pups of both sexes which moved westward from King George Island into the Pacific sector of the Antarctic Ocean as revealed in a previous tracking study. It needs to be verified whether such separation is maintained within and between years.

Description: Twenty-seven adult male southern elephant seals were immobilised to enableattachment of satellite transmitters and to obtain tissue samples. Large AnimalImmobilon (LA Immobilon) was injected remotely to achieve initial sedation(x=0,0009 mg/kg etorphine; 0.0037 mg/kg acepromacine) while ketamine wasinjected manually on demand to maintain narcosis (x=81 min). The total dosages(x=1,7 mg/kg) of ketamine required were negatively correlated with those ofLA Immobilon (p 〈 0,01). The dosages of LA Immobilon were approximately15 to 30 times lower than recommended for other large-sized mammal species,and the therapeutic range was low. Nine cases required the application of theetorphine-antidote Large Animal Revivon (x=0,0052 mg/kg diprenorphine) injectedintraveneously (n=3), intramuscularly (n=5), or sublingually (n=1). LA Immobilonappears to be useful to attain immobilisation in adult male southern elephantseals by remote injection owing to its high potency and hence small volume required.It must, however, be used sparingly and ideally for initial sedation due to its potentialdanger and narrow therapeutic margin.

Description: Extended AbstractStudies on wild pinnipeds such as blood and tissue sampling or attachment ofinstruments usually require immobilization. This is particularly true for adult malesouthern elephant seals whose body mass generally exceeds 2 tons, and hence,a suitable chemical restraint is required for any handling. Therefore, both appropriatedrugs and a remote delivery system as generally applied in wild animal research isrequired (CLINE et al., 1969; TRILLMICH and WIESNER, 1979; KOCK, 1987; BUSH,1992). Wild elephant seals are only accessable during their onshore-periods whilebreeding and moulting. At this time, they fast and hence undergo considerablemetabolic changes. The individuals' constitutions are then highly variable, and thereaction to external stimuli ranges from being calm to being aroused. Thereby, thedosage of drugs is hardly to assess, and the response to drugs is variable(HAMMOND and ELSNER, 1977). Estimation of body mass is also difficult sincemoulting males tend to aggregate tightly in large groups when ashore, occasionallylying over and over. The harsh field conditions in polar regions aggravate the workadditionally. Therefore, both a sturdy drug delivery system, and some considerationson the methods of application are recommended.In the present study, 27 animals were immobilized to obtain subcutaneous tissuesamples, and to attach satellite linked dive recorders to their pelage at the end oftheir annual moult. Prior to immobilization, doses were calculated roughly basedon the estimated body mass. Immo-bilization was performed in two steps. Firstly,Large Animal Immobilon® (LA Immobilon®) was injected remotely to achieveinitial sedation (x=0.0009 mg/kg etorphine; 0.0037 mg/kg acepromacine). As thesecond step, if breathing and reflexes occured regularly, ketamine wassubsequently injected by hand to maintain narcosis (x=81 min). Nine casesrequired the application of the etorphine-antidote Large Animal Revivon®(x=0.0052 mg/kg diprenor-phine) injected intraveneously (n=3), intramuscularly(n=5), or sublingually (n=1) to antagonize side effects such as prolonged apneaand/or decrease of reflexes.Results and DiscussionThe total dosages of ketamine required to maintain narcosis (x=1.7 mg/kg) werenegatively correlated with those of LA Immobilon® (p〈0.01). The dosages ofLA Immobilon® were approximatelly 15-30 times lower than recommended forother large-sized mammal species including marine mammals (ALFORT et al.,1974; BORN and KNUTSEN, 1990; GRIFFITH et al., 1993), and the therapeuticrange was low. LA Immobilon® appears nevertheless to be useful as a first-stepimmobilization agent in adult male southern elephant seals owing to its smallvolume required for remote injection, and the possibility of high specificantagonization by Large Animal Revivon®. We nevertheless suggest thatLA Immobilon® should only be used as a kind of pre-medication, not usedrepeatedly in the same individual, and solely if high specific antidote(Large Animal Revivon®) is availlable. It has further to be realized thatLA Immobilon® is potentially dangerous for personnel, especially when usedin remote areas. Therefore, both the specific morphine-antidote for humans(Narcanti®), and trained field personnel should be aboard.