Carlini.indd 139Carlini et al. 2006: Polar Research 25(2), 139–144 Haul-out pattern of itinerant male Antarctic fur seals (Arctocephalus gazella) at Laurie Island, South Orkney Islands Alejandro R. Carlini, Gustavo A. Daneri, Ricardo Casaux, María E. I. Márquez The seasonal haul-out pattern of itinerant male Antarctic fur seals (Arcto- cephalus gazella) was determined by regular counts at Mossman Penin- sula, Laurie Island, South Orkney Islands, from 1996 to 2005. Small numbers of animals began to arrive at the beach in late December / early January (mean date 28 December ± 15 days, n = 10). Peak numbers of ani- mals ashore changed considerably between seasons. In 1996, 1998 and 2001, peak numbers were registered in March (6/3, 18/3 and 6/3, respec- tively). Numbers peaked in 1997, 1999 and 2005 at the end of January / be- ginning of February (26/1, 2/2 and 28/1, respectively). In 2000, 2002, 2003 and 2004 peaks were registered in the third week of February (15/2, 22/2, 14/2 and 20/2, respectively). Peaks in numbers of seals ashore also varied between years, being minimum during 2001 (2531 individuals) and maxi- mum during 2006 (16 610 individuals). In March 1998 the coasts of Laurie Island were surveyed by navigating infl atable boats near the shoreline; 18 haul-out places were identifi ed. The big differences in peak numbers, as well as in the dates of peak events among years, suggest that local condi- tions could have an effect on the numbers of animals hauled out in a given year. It may therefore be diffi cult to predict trends from summer censuses in non-breeding places. A. R. Carlini, R. Casaux & M. E. I. Márquez, Depto. de Ciencias Biológicas, Instituto Antártico Argentino, Cerrito 1248, C1010 AAZ Buenos Aires, Argentina, acarlini@dna.gov.ar; G. A. Daneri, División Masto- zoología, Museo Argentino de Cs. Naturales “B. Rivadavia”, Av. Angel Gallardo 470, C1405 DJR Buenos Aires, Argentina. Antarctic fur seals (Arctocephalus gazella Peters, 1875) were subjected to an extensive commercial harvest and nearly exterminated during the 19th and early 20th centuries (Bonner 1968). Since the cessation of sealing a substantial recovery of the population has taken place from small rem- nant breeding groups located around South Geor- gia and Bouvetøya (Bouvet Island) (Bonner 1968; Payne 1977; Boyd 1993; Wynen et al. 2000). At present, the main breeding locations are at Bird Island and at the western end of South Georgia (Boyd 1993), although breeding colonies have been re-established throughout the Scotia Arc and elsewhere (Bengtson et al. 1990). There are no important breeding places in the South Orkney Islands, probably because the archipelago as a whole has too short an ice-free summer to allow successful breeding (Kightley & Caldwell 1982). Laws (1981) identifi ed breed- ing colonies at Monroe Island, Gosling Islands and Michelsen Island, comprising around 100 pups. Additionally, Kightley & Caldwell (1982) 140 Haul-out pattern of itinerant male Antarctic fur seals reported the fi rst birth on Signy Island in Febru- ary 1987. Total pups born in the archipelago were recently estimated to be less than 1000 (SCAR Expert Group on Seals 2004). No breeding groups have been reported at Laurie Island and only four births have been recorded there. However, an important group of non-breeding adult and sub- adult males is present during the summer at this location (Vergani & Coria 1989). The work on which this paper is based was carried out at Laurie Island over 10 consecutive years. The study presents information on the haul- out pattern of itinerant male Antarctic fur seals at Mossman Peninsula and provides the results of the fi rst survey of the whole coast of the island. Materials and methods The study was carried out at Mossman Peninsula, Laurie Island (60° 45' S, 44° 43' W), South Orkney Islands, from 1996 to 2005 (Fig. 1). Antarctic fur seals were counted weekly throughout the year by two observers on foot along the approximate- ly 4 km of coast between the Argentinean Orca- das Station and Point Martin (sites A, B, C, D, E on Fig. 1). The same observers who counted the animals in one year trained, for about one month, two other observers for the following year. When groups had over 3000 seals, which generally occurred in site C for some seasons, three inde- pendent counts were made from a cliff and the average value was calculated. Animals were not sorted into age classes but they were mainly adult and sub-adult males. Between 6 and 13 March 1998 the coasts of Laurie Island were surveyed by navigating infl at- able boats near the shoreline to identify addition- al haul-out places. Since animals began to arrive in December, reports for a given year in this work include data from December of the previous year (i.e. the number of seals reported for 1996 includes December 1995). Results and discussion Small numbers of animals began to arrive at the beach in late December / early January (mean date 28 December ± 15 days, n = 10), and num- bers started to increase from the second week Fig. 1. Haul-out places (grey dots) of itinerant Antarctic fur seals (Arctocephalus gazella) in March 1998 at Laurie Island, South Orkney Islands. A–E mark sites where weekly counts were made. 141Carlini et al. 2006: Polar Research 25(2), 139–144 Date Date Date Date Date Date Date Date Date Date 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 N um be r of s ea ls N um be r of s ea ls N um be r of s ea ls N um be r of s ea ls N um be r of s ea ls N um be r of s ea ls N um be r of s ea ls N um be r of s ea ls N um be r of s ea ls N um be r of s ea ls 6/3 0 2000 4000 6000 8000 10000 12000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 26/1 0 2000 4000 6000 8000 10000 12000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 18/3 0 2000 4000 6000 8000 10000 12000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 2/2 0 2000 4000 6000 8000 10000 12000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 15/2 0 2000 4000 6000 8000 10000 12000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 31 /7 28/1 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 31 /7 20/2 0 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 14/2 0 2000 4000 6000 8000 10000 12000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 26/2 0 2000 4000 6000 8000 10000 12000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 6/3 0 2000 4000 6000 8000 10000 12000 4/ 12 14 /1 2 24 /1 2 3/ 1 13 /1 23 /1 2/ 2 12 /2 22 /2 3/ 3 13 /3 23 /3 2/ 4 12 /4 22 /4 2/ 5 12 /5 22 /5 1/ 6 11 /6 21 /6 1/ 7 11 /7 21 /7 2000 4000 6000 8000 10000 12000 Fig. 2. Changes in the number of itinerant Antarctic fur seals (Arctocephalus gazella) present on the study beach at Laurie Island from 1996 to 2005. Reports for a given year include data from December of the previous year. 142 Haul-out pattern of itinerant male Antarctic fur seals of January (Fig. 2). The peak number of animals ashore varied among seasons (Table 1, Fig. 2). In 1996, 1998 and 2001, peak numbers were reg- istered in March (6/3, 18/3 and 6/3, respective- ly). In 1997, 1999 and 2005 numbers peaked at the end of January / beginning of February (26/1, 2/2 and 28/1, respectively). In 2000, 2002, 2003 and 2004 peaks were registered in mid-Febru- ary (15/2, 22/2, 14/2 and 20/2, respectively). The haul-out period for non-breeding Antarctic fur seals was also reported for Heard Island by Page et al. (2003), who observed that the number of sub-adult and adult males increased markedly from late January, with the highest numbers reg- istered between 23 February and 9 March. Simi- larly, at Signy Island (South Orkney Islands) the annual summer immigration amounted to 20 500 individuals, with peak numbers also occurring in February (Smith 1997), while at Marion Island, maximum numbers of adult and sub-adult males occurred during the autumn moulting peak in March (Kerley 1983). The dates of peak numbers in most years at Laurie Island (February–March) are similar to those found at the above-mentioned localities, which would be accounted for by ani- mals coming ashore during their moulting period. However, in some years (1997, 1999, 2005) peak numbers of animals ashore occurred in late Jan- uary / early February, although in these “atypi- cal” years a second lower peak followed in Feb- ruary–March (Table 1, Fig. 2). Between August and November, in some of the years, there were very few animals on the beach. For this period, maximum numbers occurred in October in 1996, 2001, 2003 and 2004 (37, 103, 27 and 34 fur seals, respectively), but in August in 1999. No fur seals were observed in 1997, 1998, 2000 or 2002 for the same period. Total numbers of animals ashore at Laurie Island at peak haul-out varied enormously among years, with lowest numbers in 2001 (2531 animals) and a maximum in 2005 (16 610 animals) (Fig. 3). Such a variation in seals’ numbers could be related to an ocean wide event such as El Niño–Southern Oscillation (ENSO). ENSO has a profound effect on the weather and oceanic conditions across the tropical Pacifi c, where it has its origin. It has been suggested that the effects of ENSO might be trans- mitted from the tropical Pacifi c Ocean to the Ant- arctic (Turner 2004). This could cause changes in physical environmental variables, fi nally affect- ing the numbers of animals observed. We could not fi nd a clear connection between the number of seals at peak haul-out and ENSO. El Niño events (1997/1998 and 2002/2003) or La Niña events (1998/1999 and 2000/2001) involved seasons with 0 2000 4000 6000 8000 10000 12000 14000 16000 18000 19 85 19 86 19 87 19 96 19 97 19 98 19 99 20 00 20 01 20 02 20 03 20 04 20 05 Year N um be r o f s ea ls a t pe ak h au l-o ut Fig. 3. Numbers of Antarctic fur seals (Arctocephalus gazella) at peak haul-out. Data for 1985–87 from Vergani & Coria (1989); data for 1996–2005 from this study. Table 1. Dates and numbers of itinerant Arctocephalus gazella at peak haul-out from 1996 to 2005 at Mossman Peninsula, Laurie Island. Year Main peak event Date Numbers 1996 6 March 5559 1997 26 January 11 577 1998 18 March 4163 1999 2 February 5778 2000 15 February 9368 2001 6 March 2531 2002 26 February 7635 2003 14 February 5160 2004 20 February 7164 2005 28 January 16 610 143Carlini et al. 2006: Polar Research 25(2), 139–144 similar numbers of seals at Laurie Island at peak haul-out (Table 1, Fig. 2). Considering the previous census in the area (Vergani & Coria 1989), it seems likely that there has been an increase in the numbers of Antarctic fur seals that haul out on the beaches in the study area (Fig. 3). However, the big inter-annual dif- ferences in numbers together with the variations in the peak dates, support the idea that local con- ditions, with their potential effects on food avail- ability in the area, could have an effect on the numbers of animals hauled out in a given year. It may therefore be diffi cult to predict trends from summer censuses in non-breeding places. A total of 18 haul-out places were identifi ed from the survey of the Laurie Island coast in March 1998 (Fig. 1). Because observers were not able to land to count seals, we lack accurate esti- mates of animals at these sites. Nevertheless, it was possible to observe that site C at Mossman Peninsula shelters the biggest haul-out place at Laurie Island, while the second largest concen- tration of animals was identifi ed at site F (Fig. 1). Fur seals at Laurie Island are probably immi- grants from South Georgia (Kightley & Cadwell 1982), which is home to the largest fur seal popu- lation and accounts for around 95 % of total pup production for the species (Boyd 1993), with the current population estimated at over three mil- lion individuals (Barlow et al. 2002). Availa- ble data from South Georgia indicate an annual increase in pup production of 16.8 % from 1957 to 1972 (Payne 1977) and 9.8 % from 1976 to 1990, as well as an expansion of the breeding range (Boyd 1993). It has been suggested that a possi- ble reason for the decline in the annual increase in the South Georgia population is that emigration is taking place from the traditional breeding sites, some of which have reached their capacity (Boyd 1993). The South Orkney Islands are similar to South Georgia in that high densities of krill can be found nearby (Everson & Goss 1991; Kasat- kina et. al 1997). Availability of krill is a critical factor in determining breeding locations, since fur seals depend on rich localized food resources, especially during lactation (Costa 1991). In spite of this, only four pups were born at the study site on Laurie Island over the 10-year study period, suggesting that the south coasts of Laurie Island are not suitable breeding areas for the species, probably because they are often covered by ice until December. Coincidentally, a survey of Ant- arctic fur seals in the South Shetland Islands indi- cated that no pupping sites were located on the southern coasts of these islands along the Brans- fi eld Strait (Bengtson et al. 1990). According to these authors, the absence of pups on these coasts would suggest that newly occupied pupping sites may be vulnerable to disturbance (e.g. human, climatic factors) until a traditional pupping site is established and the rookery has become suf- fi ciently large and socially stable to persist and grow. This explanation would fi t well to the phe- nomenon observed at Laurie Island. Acknowledgements.—We would like to express our grati- tude to the staff of the Administración de Parques Nacion- ales: R. Cerda, S. Vellido, E. Luoni, O. Jensen, A. Georgópu- los, C. Quintana, R. Zalazar, M. Calvi, R. Cerdá, M. Gray, G. Willink, A. Seuferheld, A. Sanchez, F. Ferioli, G. Porro, G. Sanchez, G. Carreras, P. Rosso, A. Dalmasso, R. Amado, A. Beati, D. Saad and E. Rombola for fi eld assistance. We thank the members of the Orcadas Station for their logistic support. We want to thank two anonymous reviewers for their helpful comments on the manuscript. References Barlow, K. E., Boyd, I. 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L. 1997: Impact of an increasing fur seal popula- tion on Antarctic plant communities: resilience and recov- << /ASCII85EncodePages false /AllowTransparency false /AutoPositionEPSFiles true /AutoRotatePages /None /Binding /Left /CalGrayProfile (Dot Gain 10%) /CalRGBProfile (Apple RGB) /CalCMYKProfile (U.S. Sheetfed Coated v2) /sRGBProfile (sRGB IEC61966-2.1) /CannotEmbedFontPolicy /Warning /CompatibilityLevel 1.3 /CompressObjects /Tags /CompressPages true /ConvertImagesToIndexed true /PassThroughJPEGImages true /CreateJDFFile false /CreateJobTicket false /DefaultRenderingIntent /Default /DetectBlends true /ColorConversionStrategy /LeaveColorUnchanged /DoThumbnails false /EmbedAllFonts true /EmbedJobOptions true /DSCReportingLevel 0 /SyntheticBoldness 1.00 /EmitDSCWarnings false /EndPage -1 /ImageMemory 1048576 /LockDistillerParams false /MaxSubsetPct 100 /Optimize true /OPM 1 /ParseDSCComments true /ParseDSCCommentsForDocInfo true /PreserveCopyPage true /PreserveEPSInfo true /PreserveHalftoneInfo true /PreserveOPIComments true /PreserveOverprintSettings true /StartPage 1 /SubsetFonts false /TransferFunctionInfo /Preserve /UCRandBGInfo /Preserve /UsePrologue false /ColorSettingsFile () /AlwaysEmbed [ true ] /NeverEmbed [ true ] /AntiAliasColorImages false /DownsampleColorImages false /ColorImageDownsampleType /Average /ColorImageResolution 300 /ColorImageDepth -1 /ColorImageDownsampleThreshold 1.50000 /EncodeColorImages true /ColorImageFilter /DCTEncode /AutoFilterColorImages true /ColorImageAutoFilterStrategy /JPEG /ColorACSImageDict << /QFactor 0.15 /HSamples [1 1 1 1] /VSamples [1 1 1 1] >> /ColorImageDict << /QFactor 0.15 /HSamples [1 1 1 1] /VSamples [1 1 1 1] >> /JPEG2000ColorACSImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /JPEG2000ColorImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /AntiAliasGrayImages false /DownsampleGrayImages false /GrayImageDownsampleType /Average /GrayImageResolution 300 /GrayImageDepth -1 /GrayImageDownsampleThreshold 1.50000 /EncodeGrayImages true /GrayImageFilter /DCTEncode /AutoFilterGrayImages true /GrayImageAutoFilterStrategy /JPEG /GrayACSImageDict << /QFactor 0.15 /HSamples [1 1 1 1] /VSamples [1 1 1 1] >> /GrayImageDict << /QFactor 0.15 /HSamples [1 1 1 1] /VSamples [1 1 1 1] >> /JPEG2000GrayACSImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /JPEG2000GrayImageDict << /TileWidth 256 /TileHeight 256 /Quality 30 >> /AntiAliasMonoImages false /DownsampleMonoImages false /MonoImageDownsampleType /Average /MonoImageResolution 1200 /MonoImageDepth -1 /MonoImageDownsampleThreshold 1.50000 /EncodeMonoImages true /MonoImageFilter /CCITTFaxEncode /MonoImageDict << /K -1 >> /AllowPSXObjects false /PDFX1aCheck false /PDFX3Check false /PDFXCompliantPDFOnly false /PDFXNoTrimBoxError true /PDFXTrimBoxToMediaBoxOffset [ 0.00000 0.00000 0.00000 0.00000 ] /PDFXSetBleedBoxToMediaBox true /PDFXBleedBoxToTrimBoxOffset [ 0.00000 0.00000 0.00000 0.00000 ] /PDFXOutputIntentProfile (None) /PDFXOutputCondition () /PDFXRegistryName (http://www.color.org) /PDFXTrapped /Unknown /Description << /JPN /FRA /DEU /PTB /DAN /NLD /ESP /SUO /ITA /NOR /SVE /ENU >> >> setdistillerparams << /HWResolution [2400 2400] /PageSize [595.276 822.047] >> setpagedevice