MARINE MAMMAL SCIENCE, 25(2): 455–461 (April 2009)C© 2009 by the Society for Marine MammalogyDOI: 10.1111/j.1748-7692.2008.00276.x

Movements of southern right whales (Eubalaena australis) betweenAustralian and subantarctic New Zealand populations

REBECCA PIRZL

School of Life and Environmental Sciences,Deakin University, PO Box 423,

Warrnambool, Victoria 3280, AustraliaE-mail: rpirzl@ozemail.com.au

NATHALIE J. PATENAUDE

LGL Limited,22 Fisher Street,

King City, Ontario L7B 1A6, Canada

STEPHEN BURNELL

South Australian Museum,North Terrace,

Adelaide, South Australia 5000, Australia

JOHN BANNISTER

Western Australian Museum,Locked Bag 49,

Welshpool DC, Westerian Australia 6986, Australia

Southern right whales (Eubalaena australis) are a highly mobile migratory specieswith a circumpolar distribution between about 20◦S and 60◦S. A total of 11 wintercalving grounds have been identified in the southern hemisphere based on thedistribution of current or historical sightings and catches (IWC 2001). At leastfour discrete biological populations winter in population-specific ranges off thecoasts of Australia, South Africa, Argentina, and subantarctic New Zealand (IWC2001). Seasonal migration between winter calving grounds and summer feedinggrounds, generally at higher latitudes, is well accepted (e.g., Bannister et al. 1997), butdocumented long-range movements between population wintering ranges are rare,and until now were confined to the South African and Argentine populations (Bestet al. 1993). We compared photo-identifications from Australian and subantarcticNew Zealand ranges, and found three between-population movements, includingtwo instances of females calving in each of two population-specific calving grounds.

Photo-identification studies utilizing unique callosity patterns (cornified skin areason the head) and body markings to catalog individuals (Kraus et al. 1986) have beenused extensively for demographic and movement studies of southern right whales(Payne et al. 1983, Payne 1986, Bannister 1990, Best 1990). Within population win-tering ranges, coastal movements of hundreds of kilometers are common, particularlyamong unaccompanied adults (an adult whale without a calf of the year), and calvingground shifts by calving females (a female accompanied by a calf of the year) occur

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occasionally (Burnell 2001, Rowntree et al. 2001). Movements between populationwintering ranges are apparently rare. An unaccompanied female sighted at GoughIsland in the South Atlantic was photographed in a different year off South Africawith a calf, while a male moved between Tristan da Cunha in the South Atlantic andArgentina (Best et al. 1993). It remains unclear whether a further three movementsof females sighted in calving grounds off Brazil and Argentina in different years, twowith a calf on each occasion, represented calving ground shifts between populationsor migratory movements through one calving ground en route to another (Best et al.1993). More recent comparisons found no additional evidence of movement betweenSouth Africa and Argentina (Rowntree et al. 2001). The findings reported here are thefirst to document movement between population-specific ranges for the Australianand subantarctic New Zealand populations, including movements of calving femalesbetween population-specific calving grounds.

Cataloged images of Australian and subantarctic New Zealand right whales werecompared at Australasian photo-identification workshops in 2002 and 2004. Pho-tographs were available from southwestern Australia (115.0◦E–133.5◦E), southeast-ern Australia (141◦E–152◦E), the Head of Bight calving ground in South Australia(31◦29′S, 131◦05′E), and the Auckland (50◦32′S, 166◦15′E) and Campbell islands(52◦35′S, 169◦10′E) in subantarctic New Zealand. The majority of identificationimages compared were obtained in systematic studies from 1976 onwards in south-western Australia (Bannister), 1991 onwards at Head of Bight (Burnell), and between1995 and 1998 in subantarctic New Zealand (Patenaude/Todd), with some oppor-tunistic images from southeastern Australia (curator M. Watson1).

All images were taken with 35-mm SLR (Nikon) or square format 2” ×2” (Bronica) cameras on either color transparency film (Australia) or black andwhite print film (New Zealand). Identification images from southwestern and south-eastern Australia comprised “topside” (from above) images taken from fixed wingaircraft with various telephoto lenses (Bannister 1990, Kemper et al. 1997). Headof Bight identifications comprised topside, left and right lateral, and ventral imagestaken from 40–60-m high cliffs using a 1,000-mm lens (Burnell and Bryden 1997).Subantarctic New Zealand identifications comprised mainly lateral and some top-side images taken with various telephoto lenses from a small motorized boat andoccasionally from the mast of a sailing vessel or cliff tops (Patenaude et al. 2001).

Identification images were compared manually by a small group of people expe-rienced in right whale photo-identification and matching. All matches were inde-pendently verified by at least three researchers. Subsets of readily comparable imageswere matched rather than entire catalogues due to time and funding constraints.Dorsally blazed or partial albino Australian identifications (50) were cross-matchedwith similarly marked New Zealand whales (54); topside Australian images (591)were matched to topside New Zealand images (27); left lateral Australian images(30) were matched to equivalent New Zealand identifications (600); and in morecomplex comparisons 51 topside Australian images were matched to 472 lateral

1Mandy Watson, Department of Sustainability and Environment, 78 Henna Street, Warrnambool,VIC 3280, Australia.

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Table 1. Resight history of individual southern right whales matched between Australianand subantarctic New Zealand populations.

Distance from PopulationDate/s Breeding last sighting range

Individual photographed Site status (km) movement

H9362/NAI81 1990 HOB A – –1993 (19–29 Sep) HOB A 0 No1996 (30 Jul–04 Aug) AI C 3,630 Yes2000 (02–05 Oct) HOB C 3,630 Yes

H9410/NAI316 1994 (01 Aug) HOB C – –1998 (27 Jul–04 Aug) AI C 3,630 Yes

W252/NT465 1996 (07 Aug) AI A – –1998 (12 Aug) AI A 0 No1999 (01 Sep) EMS A 3,740 Yes

HOB = Head of Bight (31◦28′S, 131◦08′E); AI = Auckland Islands (50◦32′S, 166◦15′E);EMS = east of Merdayerrah Sandpatch, South Australia (31◦39′S, 129◦16′E); A = unaccom-panied adult; C = female accompanied by a calf of the year.

New Zealand images. As individual whales were occasionally cataloged in morethan one dataset and photo-identification effort was highly variable among the dif-ferent study areas, it was not possible to quantify effort; however, few matcheswere made relative to the number of individual identifications cataloged and thenumber of comparisons completed. Movements of three individual right whalesbetween Australian and subantarctic New Zealand coastal waters were confirmed(Table 1,Fig. 1).

Two females with calves (H9362/NAI81 and H9410/NAI316) were photo-identified in different years (3 and 4 yr apart) at both the Head of Bight andthe Auckland Islands calving grounds (3,630 km distance) suggesting that each hadcalved at least once within each winter range. Within season travel to an alterna-tive calving ground following birthing is an unlikely explanation for the observedsightings given their timing, the long distance between the two locations, andthe unlikely capacity of young calves to make such movements. In addition to thedocumented movements of reproductive females, one unaccompanied adult of un-known sex (W252/NT465) moved between the Auckland Islands and MerdayerrahSandpatch in southern Australia (31◦39′S, 129◦16′E) (3,740 km distance), betweenwinter 1998 and winter 1999. Two of the three sightings of this individual weremade at the Auckland Islands, including one sighting in a social group.

The low number of resights and disparate photo-identification effort betweenpopulations confounded any attempt to determine whether calving ground shiftswere temporary or permanent. Fidelity of H9410/NAI316 to the Australian rangewas presumably weak as it was seen during only one winter season despite severaldecades of coastal survey effort and its very conspicuous dorsal markings. Further, itwas sighted on only one day at Head of Bight compared with an average residencytime there for females with calves of 71 d (Burnell and Bryden 1997). The perma-nency or otherwise of calving ground shifts has implications for the estimation of

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Figure 1. Movements of individual southern right whales between Australian and sub-antarctic New Zealand populations.

biological parameters (such as calving intervals) used to monitor populations, andthe interpretation of data (such as visitation rates) used to estimate abundance andrecovery trends from coastal surveys. As the incidence of shifts is apparently low, theimplications are expected to be minor.

The apparent rarity of movement between population-specific wintering rangesmay be an artifact of incomplete cross-population photo-identification comparisons,but genetic evidence from analysis of mitochondrial DNA (mtDNA) sequences andhaplotype frequencies also suggests only limited movement. Low level gene flow hasbeen found to occur primarily between adjacent populations within an ocean basinbetween South Africa and Argentina (Portway et al. 1998) and between subantarcticNew Zealand and Australia (Baker et al. 1999), with very limited flow between theSouth Atlantic and Indo-Pacific basins (Patenaude et al. 2007).

The mechanism for gene flow between southern right whale populations is un-known, but a small body of photo-identification data now indicates that it may resultfrom intermixing of reproductively mature whales in population-specific winteringranges. Mating is commonly observed near shore in both Australia and subantarcticNew Zealand (Burnell et al. 1990, Patenaude and Baker 2001) and the presenceof W252/NT465 in a socially active group at the Auckland Islands, then later offthe Australian coast indicates the possibility of gene flow via unaccompanied adultmovement between winter ranges. Should movements of males be taking place, male-mediated gene flow not detected in mtDNA structure may occur. The movements

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of calving females H9362/NAI81 and H9410/NAI316 indicate another possiblemechanism for gene flow: one mediated by the site fidelity tendencies of offspringand dependent on calving ground shifts by pregnant females. Individuals are knownto return in later years to the location where they were born (e.g., 85% of resightedcalves born at Head of Bight exhibited a degree of fidelity to that site (Burnell 2001)),where they engage in mating behavior and give birth (Payne et al. 1990, Burnell2001). Fidelity mediated gene flow may arise when a pregnant female, having con-ceived within the population with which it is genetically affiliated, gives birth ina different population-range, and the offspring then shows fidelity to, and breedswithin, its birthing population-range.

The cause of movements between population-specific wintering ranges remainsunclear. Patenaude et al. (2007) proposed that female movement may have beenrestricted as a consequence of population depletions by whaling. It is possible thatmovements between grounds are density dependent and may increase as populationsrecover. The movements may also indicate a non-density dependent meta-populationstructure for southern right whales in which limited movement between geneticallydifferentiated populations occurs. Large distances between populations, combinedwith strong philopatry may effectively fragment the species into naturally spatiallyseparated populations. Photo-identification resight data support the possibility ofa meta-population structure with low levels of interaction, but do not provideconclusive evidence.

It is now clear that southern right whales occasionally move between Australianand subantarctic New Zealand population-specific ranges, and the breeding statusof the individuals involved supports the possibility of low level gene flow via in-termixing in winter habitat. The photo-identification comparisons reported hereoffer insights into current movement patterns, enhancing the historical perspectiveprovided by genetic studies. Comprehensive cross-matching of southern hemisphereidentification catalogues could elicit further information on the linkages betweensouthern hemisphere right whale populations.

ACKNOWLEDGMENTS

The authors thank Philip Hamilton, Catherine Kemper, Robyn McCulloch, Desray Reeb,Victoria Rowntree, Lex Hiby, Mandy Watson, and Ian Westhorpe for assistance with imagematching, Barbara Todd and Mandy Watson for access to photo-identification images, andnumerous field staff for data collection. BHP and the Australian Department of the Environ-ment, Water, Heritage and the Arts (DEWHA) primarily funded Australian surveys. NewZealand surveys were funded by grants from the U.S. Department of State (Program forCooperative U.S./NZ Antarctic Research), the Auckland University Research Council, theWhale and Dolphin Conservation Society, Shell/WWF New Zealand, and the Percy SladeMemorial Fund. Non-systematic photo-identification images were contributed by a num-ber of organizations and individuals. The comparisons reported here were undertaken at aworkshop funded by DEWHA with in-kind support from the South Australian Museumand workshop participants. Bannister thanks the Trustees, Executive Director, and staff ofthe Western Australian Museum for continued support and assistance. We thank Dr. JamesEstes, Dr. Doug Nowacek, and two anonymous reviewers for comments that improved thismanuscript.

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Received: 20 November 2007Accepted: 28 August 2008