Rakiura Stewart Island and Te Ara a Kiwa IMMA

Size in Square Kilometres

25,158 km2

Qualifying Species and Criteria

Antarctic blue whale – Balaenoptera musculus intermedia

Criterion A; C (3)

Fin whale – Balaenoptera physalus

Criterion A

Hector’s dolphin – Cephalorhynchus hectori

Criterion A; B (1)

Humpback whale – Megaptera novaeangliae

Criterion A; C (3)

New Zealand fur seal – Arctocephalus forsteri

Criterion C (1)

New Zealand sea lion – Phocarctos hookeri

Criterion A; B (1); C (1)

Pygmy blue whale – Balaenoptera musculus brevicauda

Criterion A; C (3)

Sei whale – Balaenoptera borealis

Criterion A

Southern right whale – Eubalaena australis

Criterion C (1, 3)

Sperm whale – Physeter macrocephalus

Criterion A

Marine Mammal Diversity 

Criterion D (2)

Berardius arnuxii, Balaenoptera bonaerensis, Delphinus delphis, Lagenorhynchus obscurus, Orcinus orca, Hydrurga leptonyx, Globicephala melas, Caperea marginata, Mirounga leonine, Lissodelphis peronii

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Covering the southern coast of Te Waipounamu/South Island, Te Ara a Kiwa/Foveaux Strait, and the waters around Rakiura/Stewart Island, this IMMA has a wide range of marine mammal habitats from terrestrial haul out sites to shallow, coastal shelf waters to deep, off the shelf waters. Twenty one species or subspecies have been recorded in the IMMA including eight threatened marine mammals: Critically Endangered Antarctic blue whales, Endangered Hector’s dolphins, New Zealand sea lion, pygmy blue whale, humpback whale (Oceania sub-population), and sei whale, as well as Vulnerable fin whale and sperm whales. The IMMA contains the third largest breeding area for the endemic New Zealand sea lion and a small, genetically distinct population of endemic Hector’s dolphins. The IMMA is also an important migratory route for blue, southern right and humpback whales. The deeper waters to the west support sperm and beaked whales including frequent sightings and strandings of Arnoux’s beaked whales.

Description of Qualifying Criteria

Criterion A – Species or Population Vulnerability

There are eight species or subspecies found in the IMMA that meet this criterion with IUCN threatened or vulnerable status, and include Antarctic blue whale Balaenoptera musculus intermedia (CR), Hector’s dolphin Cephalorhynchus hectori (EN), New Zealand sea lion Phocarctos hookeri (EN), pygmy blue whale Balaenoptera musculus brevicauda (EN), humpback whale Megaptera novaeangliae (Oceania sub-population; EN), sei whale Balaenoptera borealis (EN), fin whale Balaenoptera physalus (VU), and sperm whale Physeter macrocephalus (VU). All these species have been reported from the IMMA (e.g. DOC Marine Mammal Sighting and Stranding database 2020) and this IMMA forms an important part of their range within New Zealand.

Criterion B: Distribution and Abundance

Sub-criterion B1: Small and Resident Populations 

New Zealand sea lions are slowly recovering within the IMMA with a new, small breeding colony established in Port Pegasus, on the south eastern coast of Rakiura, which is now the fifth largest breeding population of this endangered, endemic species with an estimate of 178 (168-194) adults and pups in 2014-2015 (Roberts & Doonan 2016). There are also a small number of additional breeding females in the Catlins (e.g. northeastern part of the IMMA). The total number of New Zealand sea lions within the IMMA is presently estimated at approximately 300-400 individuals (S. Childerhouse pers. comm.). The turbid coastal waters along the South Island coast including three large bays within the IMMA (i.e. Te Waewae, Toetoes and Porpoise Bays) form part of a small, endemic and genetically distinct sub-population of Hector’s dolphins, called the South Coast South Island sub-population (Hamner et al. 2012). These three bays are spread over approximately ~120 km of coastline but dolphins at all three sites consistently exhibit a high degree of genetic differentiation from the two other South Island sub-populations of Hector’s dolphins (Hamner et al. 2012). An aerial survey estimated a total of 332 (95% CI 217-508) Hector’s dolphins along the south coast of the South Island (e.g. the whole area is contained within the IMMA) (MacKenzie & Clement 2018), providing evidence that this sub-population is extremely vulnerable.

Criterion C: Key Life Cycle Activities

Sub-criterion C1: Reproductive Areas

Important New Zealand fur seal breeding colonies (e.g. Ruapuke Island, Bench Island, Breaksea Island, Codfish Is, Solander Island) occur on offshore Islands around Te Ara a Kiwa and Rakiura (Baird 2011) whose coastal and offshore feeding (particularly for nursing females) are constrained to feeding completely within the IMMA during the breeding season (MPI 2017). Also, as noted previously, there are important New Zealand sea lion breeding areas at Port Pegasus, Rakiura (the third largest colony for this endangered, endemic) and the Catlins on the North Island. The highest concentration of records of southern right whales are from Te Ara a Kiwa with a local hot spot in Te Waewae Bay. Te Waewae Bay was the site of the first recorded  mating of southern right whales around New Zealand post commercial whaling operations and is also a site of regular records of cow-calf pairs (Carroll et al. 2014, Cranswick et al. 2022).

Sub-criterion C3: Migration Routes

Historical whaling data confirms this IMMA as an important migration route for humpback whales (Dawbin 1956) sperm whales (Gaskin 1973) and southern right whales (Richards et al. 2009, Carroll et al. 2014), and efforts to research this important migratory route has been undertaken for humpback whales (Gibbs & Childerhouse 2000, Constantine & Riekkola 2019), sperm whales (Gaskin 1973) and southern right whales (Carroll et al. 2014, Mackay et al. 2020). Recent satellite tracking of blue whales and southern right whales), have also further confirmed that this IMMA still contains important migratory pathways for these species (Carroll et al. 2013, Goetz et al. 2018, Mackay et al. 2020, DOC Marine Mammal Sighting and Stranding database 2020).

Criterion D: Special Attributes

Sub-criterion D2: Diversity

This IMMA supports 21 different marine mammal species or subspecies recorded (e.g. DOC Marine Mammal Sighting and Stranding database 2020) and the presence of other unrecorded species highly likely. The IMMA is an important migratory route for humpback whales (Gibbs & Childerhouse 2000, Constantine & Riekkola 2019), sperm whales (Gaskin 1973) and southern right whales (Carroll et al. 2014, Mackay et al. 2020). Whilst little is known about living pilot whales in New Zealand, Rakiura is a renowned stranding site for pilot whales, including 100+ individuals, with the number of strandings increasing (Oremus et al. 2013, Betty et al. 2019). Seasonally enhanced productivity in this region may influence pilot whale occurrence (Hamilton et al. 2019) and changes in temperature (Shears & Bowen 2017) and ocean dynamics may be contributing to increased habitat use by them. The combination of shallow, coastal shelf waters and deep, submarine canyon waters provide ideal habitat for a number of other cetaceans with regular sightings of Arnoux’s beaked whales, pygmy right whales, sperm whales. There are increasing reports of leopard seals on Rakiura and the southeast coast of the South Island (Hupman et al. 2020).

Supporting Information

Baird, S.J. 2011. New Zealand fur seals – summary of current knowledge. New Zealand Aquatic Environment and Biodiversity Report No. 72. 51 p.

Baker, C.S., Boren, L., Childerhouse, S., Constantine, R., van Helden, A., Lundquist, D., Rayment, W. and Rolfe, JR. 2019. Conservation status of New Zealand marine mammals, 2019. New Zealand Threat Classification Series 29. Department of Conservation, Wellington. 18 p.

Bejder, L., and Dawson, S. 2001. Abundance, residency, and habitat utilisation of Hector’s dolphins (Cephalorhynchus hectori) in Porpoise Bay, New Zealand. New Zealand Journal of Marine and Freshwater Research 35: 277-287

Betty, E.L., Bollard, B., Murphy, S., Ogle, M., Hendriks, H., Orams, M.B., and Stockin, K.A. 2019 Using emerging hotspot analysis of stranding records to inform conservation management of a data-poor cetacean species. Biodiversity and Conservation 29: 643-665

Bradshaw, C.J.A., Davis, L.S., Purvis, M., Zhou, Q., and Benwell, G.L. 2002. Using artificial neural networks to model the suitability of coastline for breeding by New Zealand fur seals (Arctocephalus forsteri). Ecological Modelling 148: 111-131

Brough, T.E., Guerra, M., and Dawson, S.M. 2015. Photo-identification of bottlenose dolphins in the far south of New Zealand indicates a ‘new’, previously unstudied population. New Zealand Journal of Marine and Freshwater Research 49: 150-158

Carroll, E., Rayment, W., Alexander, A., Baker, C.S., Patenaude, N., Steel, D., Constantine, R., Cole, R., Boren, L., and Childerhouse, S. 2014. Reestablishment of former wintering grounds by New Zealand southern right whales. Marine Mammal Science 30(1): 206-220.

Childerhouse, S., and Gales, N. 1998. Historical and modern distribution and abundance of the New Zealand sea lion Phocarctos hookeri. New Zealand Journal of Zoology 25: 1-16

Chilvers, B.L. 2018. New Zealand Sea Lion: Phocarctos hookeri. In: Würsig B, Thewissen JGM, Kovacs KM (eds). Encyclopedia of Marine Mammals (3rd Ed.), Academic Press, pp. 635-637

Constantine, R., and Reikkola, L. 2019. Fiordland Humpback Whale Sightings 2008 – 2018. Unpublished report. December 2019. 8 p.

Cranswick AS, Constantine, Hendriks H, Carroll E 2022.  Social media and citizen science records are important for the management of rarely sighted whales. Ocean and Coastal Management 226. P 106271.

Dawbin, W.H. 1956. The migration of humpback whales which pass the New Zealand coast. Trans. R. Soc. NZ 84(1): 147–96.

Gaskin, D.E. 1973. Sperm Whales in the Western South Pacific. New Zealand Journal of Marine and Freshwater Research 7(1–2): 1–20

Gibbs, N., and Childerhouse, S. 2000. Humpback whales around New Zealand. Conservation Advisory Science Notes No. 257. Department of Conservation, Wellington, New Zealand

Goetz, K., Childerhouse, S., Paton, D., Hupman, K., Constantine, R., Double, M., Andrews-Goff, V., Zerbini, A., and Olsen, P. 2018. Satellite tracking of blue whales in New Zealand waters, 2018 voyage report. Report to the Scientific Committee of the International Whaling Committee. SC/67B/SH/09 Rev2.

Hamilton, V., Evans, K., Raymond, B., Betty, E., and Hindell, M.A. 2019. Spatial variability in responses to environmental conditions in Southern Hemisphere long-finned pilot whales. Marine Ecology Progress Series 629: 207-218

Hamner, R.M., Pichler, F.B., Heimeier, D., Constantine, R., and Baker, C.S. 2012. Genetic differentiation and limited gene flow among fragmented populations of New Zealand endemic Hector’s and Maui’s dolphins. Conservation Genetics 13: 987-1002

Hupman, K., Visser, I.N., Fyfe, J., Cawthorn, M., Forbes, G., Grabham, A.A., Bout, R., Mathias, B., Benninghaus, E., Matucci, K., Cooper, T., Fletcher, L., and Godoy, D. 2020. From Vagrant to Resident : occurrence, residency, and births of leopard seals (Hydrurga leptonyx) in New Zealand waters. New Zealand Journal of Marine and Freshwater Research 54 :1-23

Lusseau, D., and Slooten, E. 2002. Cetacean sightings off the Fiordland coastline: analysis of commercial marine mammal viewing data 1996-99. Science for Conservation 187. 42 p.

Mackay, A., Bailleul, F., Carroll, E., Andrews-Goff, V., Baker, C.S., Bannister, J., Boren, L., Carlyon, K., Donnelly, D., Double, M., Goldsworthy, S., Harcourt, R., Holman, D., Lowther, A., Parra, G., and Childerhouse, S. (2020) Satellite derived offshore migratory movements of southern right whales (Eubalaena australis) from Australian and New Zealand wintering grounds. Plos One 15(5): e0231577.

MacKenzie, D.I., and Clement, D.M. 2018. Abundance and distribution of Hector’s dolphin on South Coast South Island. New Zealand Aquatic Environment and Biodiversity, Ministry for Primary Industries, Wellington, New Zealand

Ministry of Primary Industries (MPI) 2017. New Zealand fur seals. In: Aquatic Environment and Biodiversity Annual Review 2017. Compiled by the Fisheries Science Team, Ministry for Primary Industries, Wellington, New Zealand. p 104-126.

Meynier, L., Stockin, K.A., Bando, M.K.H., and Duignan, P.J. 2008. Stomach contents of common dolphins (Delphinus sp.) from New Zealand waters. New Zealand Journal of Marine and Freshwater Research 42: 257-268.

Neumann, D.R. 2001. Seasonal movements of short beaked common dolphins (Delphinus delphis) in the north-western Bay of Plenty, New Zealand: influence of sea surface temperature and El Niño / La Niña. New Zealand Journal of Marine and Freshwater Research 35: 371-374.

New Zealand Department of Conservation (DOC) 2020. Marine Mammal Sighting and Stranding database. Public database maintained by DOC on behalf of New Zealand Government. Available from marinemammals@doct.govt.nz. Accessed in June 2020.

Oremus, M., Gales, R., Kettles, H., and Baker, C.S. 2013. Genetic evidence of multiple matrilines and spatial distribution of kinship bonds in mass strandings of long-finned pilot whales, Globicephala melas. Journal of Heredity 104: 301-311

Richards, R. 2009. Past and present distributions of southern right whales (Eubalaena australis). New Zealand Journal of Zoology 36(4): 447-459

Roberts, J., and Doonan, I. 2016. Quantitative risk assessment of threats to New Zealand sea lions. New Zealand Aquatic Environment and Biodiversity Report No. 166. Ministry for Primary Industries, Wellington, New Zealand, pp.111

Rodda, J., and Moore, A. 2013. Hotspots of Hector’s dolphins on the south coast. Proceedings of SIRC NZ Conference, Dunedin, New Zealand

Shears, NT., and Bowen, M.M. 2017. Half a century of coastal temperature records reveal complex warming trends in western boundary currents. Scientific Reports 7: 14527

Würsig, B., Duprey, N., and Weir, J. 2007. Dusky dolphins (Lagenorhynchus obscurus) in New Zealand waters: present knowledge and research goals. DOC Research & Development Series 270. Department of Conservation, Wellington. 28 p.


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