Coast and Shelf Waters of Eastern Te Waipounamu IMMA

Size in Square Kilometres

31,119 km2

Qualifying Species and Criteria

Hector’s dolphin – Cephalorhynchus hectori

Criterion A; B(1)

New Zealand sea lion – Phocarctos hookeri

Criterion A; B(1)


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This IMMA consists of the continental shelf waters (out to the 200m depth contour) of the southern part of the east coast of Te Waipounamu (New Zealand’s South Island), from the Waiau River on the Marlborough coast in the north to Makati/Chaslands Mistake on the Catlins coast in the south.  The east coast of the South Island of New Zealand is important habitat for a number of delphinid and pinniped species. It includes habitat for a small, resident population of Hector’s dolphin Cephalorhynchus hectori, a species listed as endangered on the IUCN Red List that is endemic to New Zealand. The IMMA also includes important haul-out and breeding sites for the endangered endemic New Zealand sea lion Phocarctos hookeri, New Zealand sea lions have been seriously depleted by sealing and more recently by bycatch.  Likewise, Hector’s dolphin populations are below 30% of their historical numbers and some local populations have been lost. Generally, these coastal waters support a high diversity of marine mammal species.

Description of Qualifying Criteria

Criterion A – Species or Population Vulnerability

Hector’s dolphin and New Zealand sea lion are both IUCN red-listed as Endangered (Chilvers 2015). New Zealand sea lion is so listed due to the small number of breeding locations. A few small breeding colonies are found on the east coast of the South Island, with the largest mainland breeding colony on Otago Peninsula (Chilvers & Meyer 2017). Hector’s dolphin is considered Endangered based on rate of population decline over the last three generations. Both species are significantly depleted compared to their historical population size and range (e.g. Childerhouse & Gales 1988; Slooten and Dawson 2010). New Zealand sea lions were extirpated from the mainland and sea lions from Sub-Antarctic populations, including Campbell and Auckland Islands, are very slowly re-establishing colonies on the mainland (Collins et al. 2014).

Criterion B: Distribution and Abundance

Sub-criterion B1: Small and Resident Populations

There are several small, resident populations of Hector’s dolphins and New Zealand sea lions in this area, e.g off Otago (42 individuals; CV = 41%, CI = 19 – 92; Turek et al. 2013). Another small, resident population south of Otago Peninsula has been extirpated (Diver 1866, McGrath 2020). Increasing population fragmentation is a risk factor for the species as a whole. Large gaps in Hector’s dolphin distribution compromise the demographic continuity of regional populations (and the species as a whole) and make it less and less likely that dolphins eliminated by human actions (e.g. bycatch) will be replaced by dolphins from nearby populations. New Zealand sea lions have several small breeding populations in this area, including Otago Peninsula (11-18 breeding females) and Catlins (up to 6 breeding females; Chilvers & Meyer 2017). Currently, there is a very small number of breeding females on mainland New Zealand, with the only large breeding colonies on Sub-Antarctic islands (Chilvers & Meyer 2017).  Recolonisation of the mainland and establishment of additional breeding colonies is needed for the species to recover, and therefore these small resident populations of New Zealand sea lions within the IMMA are extremely significant.  New Zealand sea lions use both inshore and offshore habitat for foraging (Auge et al. 2011).

Supporting Information

Auge AA, Chilvers BL, Moore AB, Davis LS. 2011. Foraging behaviour indicates marginal marine habitat for New Zealand sea lions: remnant versus recolonising populations. Marine Ecology Progress Series 432: 247-256.

Baird, S. J. 2011. New Zealand fur seals – summary of current knowledge. New Zealand Aquatic Environment and Biodiversity Report No. 72. Ministry of Fisheries, Wellington. 50 pp.

Baker CS, Hamner RM, Cooke J, Heimeier D, Vant M, Steel D, Constantine R. 2012. Low abundance and probable decline of the critically endangered Maui’s dolphin estimated by genotype capture-recapture. Animal Conservation 16: 224-233.

Baker CS, Steel D, Hamner RM, Hickman G, Boren L, Arlidge W, Constantine R. 2016. Estimating the abundance and effective population size of Maui dolphins using microsatellite genotypes from 2015-2016, with retrospective matching from 2001 to 2016.

Brough, T., Rayment, W. J., Slooten, E., & Dawson, S. M. (2020). Spatiotemporal distribution of foraging in a marine predator: behavioural drivers of hotspot formation. Marine Ecology Progress Series, v635, 187–202.

Burkhart SM, Slooten E. 2003. Population viability analysis for Hector’s dolphin (Cephalorhynchus hectori): A stochastic population model for local populations. NZ J Mar Freshwat Res 37: 553-566.

Carroll, E. L., Rayment, W. J., Alexander, A. M., Baker, C. S., Patenaude, N. J., Steel, D., et al. (2013). Reestablishment of former wintering grounds by New Zealand southern right whales. Marine Mammal Science, 30(1), 206–220.

Childerhouse, S., & Gales, N. J. (1998). Historical and modern distribution and abundance of the New Zealand sea lion Phocarctos hookeri. New Zealand Journal of Zoology, 25(1), 1–16.

Chilvers, B.L. 2015. Phocarctos hookeri. The IUCN Red List of Threatened Species 2015: e.T17026A1306343. Downloaded on 28 June 2020.

Chilvers, B.L., Meyer, S. 2017. Conservation needs for the endangered New Zealand sea lion (Phocarctos hookeri). Aquatic Conservation: Marine and Freshwater Ecosystems 27: 846-855.

Collins, C. J., Rawlence, N. J., Prost, S., Anderson, C. N. K., Knapp, M., Scofield, R. P., et al. (2014). Extinction and recolonization of coastal megafauna following human arrival in New Zealand. Proceedings of the Royal Society B: Biological Sciences, 281(1786), 20140097–20140097.

Currey RJC, Boren LJ, Sharp BR, Peterson D 2012. A risk assessment of threats to Maui’s dolphins. Ministry for Primary Industries and Department of Conservation,

Dawson, S.M., Slooten, E., DuFresne, S., Wade, P. and Clement, D. 2004. Small-boat surveys for coastal dolphins: Line-transect surveys for Hector’s dolphins (Cephalorhynchus hectori). Fishery Bulletin 102: 441-451.

de Jager M, Hengeveld GM, Mooij WM, Slooten E. 2019. Modelling the spatial dynamics of Maui dolphins using individual-based models. Ecological Modelling 402: 59-65.

Diver P. 1866. Guide to Brighton and its environs:  Containing every information necessary for visitors to this Otago Watering Place. Fergusson and Mitchell Publishing Company, Dunedin.

DOC 2016. Department of Conservation Hector’s and Maui dolphin incident database.  Information downloaded in May 2016.

DOC 2020. Department of Conservation sightings and stranding records.

Ferreira, S.M.; Roberts, C.C. 2003. Distribution and abundance of Maui’s dolphins (Cephalorhynchus hectori maui) along the North Island West Coast, New Zealand. DOC Internal Series 93, Department of Conservation, Wellington.

Fletcher, D., Dawson, S. and Slooten, E. Designing a mark-recapture study to allow for local emigration. Journal of Agricultural, Biological and Environmental Statistics 7(4): 1-8 (2002)

Gormley, A.M., Slooten, E., Dawson, S.M., Barker, R.J., Rayment, W., du Fresne, S. and Bräger, S. 2012. First evidence that marine protected areas can work for marine mammals. J. Appl. Ecol. 49:474-480.

Hamner RM, Oremus M, Stanley M, Brown P, Constantine R, Baker CS 2012. Estimating the abundance and effective population size of Maui’s dolphins using microsatellite genotypes in 2010-11, with retrospective matching to 2001-07. Department of Conservation Report available from

IUCN 2008. Listing of Hector’s dolphin on International Union for Conservation of Nature’s Red List of Threatened Species.

IUCN 2012. Resolution 142. Actions to avert the extinctions of rare dolphins: Maui dolphins, Hector’s dolphins, Vaquita porpoises and South Asian river and freshwater dependent dolphins and porpoises.

IWC 2016a. Report of the Scientific Committee of the International Whaling Commission. IWC/66/Rep01, reporting on the meeting of the Scientific Committee in Bled, Slovenia 7-19 June 2016.

IWC 2016b. Information downloaded from International Whaling Commission webpage during May 2016:  Scientific Committee Progress Reports from 2002 onwards:  Older reports available from:!collection73&k=

Jackson, J. A., Carroll, E. L., Smith, T. D., Zerbini, A. N., Patenaude, N. J., & Baker, C. S. (2016). An integrated approach to historical population assessment of the great whales: case of the New Zealand southern right whale. Royal Society Open Science, 3(3), 150669–16.

Leunissen, E., Rayment, W.J. and Dawson, S.M. Impact of pile-driving on Hector’s dolphin in Lyttelton Harbour, New Zealand. Marine Pollution Bulletin. 142: 31-42. 2019. (example of non-bycatch impact)

MacKenzie DL, Clement DM 2014. Abundance and distribution of ECSI Hector’s dophin. New Zealand Aquatic Environment and Biodiversity Report 123, Report to Ministry for Primary Industries, Wellington, New Zealand. March 2014.

MacKenzie DL, Clement DM 2016. Abundance and distribution of WCSI Hector’s dophin. New Zealand Aquatic Environment and Biodiversity Report 168, Report to Ministry for Primary Industries, Wellington, New Zealand. March 2014.

Manning L and Grantz K. 2017. Endangered Species Act Status Review Report for Hector’s Dolphin (Cephalorhynchus hectori). Report to the National Marine Fisheries Service, Office of Protected Resources, Silver Spring, Maryland. 90 p.

Martien KK, Taylor BL, Slooten E, Dawson S. 1999. A sensitivity analysis to guide research and management for Hector’s dolphin. Biol Conserv 90: 183-191.

McGrath G. 2020. The history of New Zealand / Aotearoa dolphins Cephalorhynchus hectori abundance and distribution. MSc thesis, University of Otago, Dunedin, New Zealand.

Meyer S, Robertson BC, Chilvers BL, Krkosek M. 2017 Marine mammal population decline linked to obscured bycatch. PNAS 114 (44) 11781-11786.

Rayment, W., Dawson, S., Scali, S. and Slooten, E. Listening for a needle in a haystack: Passive acoustic detection of dolphins at very low densities. Endangered Species Research 14: 149-156 (2011)

Rayment, W., Dawson, S.M. and Slooten, E. 2010. Seasonal changes in distribution of Hector’s dolphin at Banks Peninsula, New Zealand: implications for protected area design. Aquatic Conservation: Marine and Freshwater Ecosystems 20: 106-116, DOI: 10.1002/aqc.1049

Reeves, R.R.; Dawson, S.M.; Jefferson, T.A.; Karczmarski, L.; Laidre, K.; O’Corry-Crowe, G.; Rojas-Bracho, L.; Secchi, E.R.; Slooten, E.; Smith, B.D.; Wang, J.Y.; Zhou, K. 2013. Cephalorhynchus hectori . The IUCN Red List of Threatened Species 2013: e.T4162A44199757.

Robertson, B.C. & Chilvers, BL. 2011. The population decline of the New Zealand sea lion Phocarctos hookeri: a review of possible causes. Mammal Review, 41: 253–275.

Russell K. 1999. The North Island Hector’s dolphin: a species in need of conservation. Unpublished MSc thesis, University of Auckland, New Zealand.

Slooten E 2013. Effectiveness of area-based management in reducing bycatch of the New Zealand dolphin. Endangered Species Research 20: 121-130.

Slooten E, Dawson SM. 2010. Assessing the effectiveness of conservation management decisions: Likely effects of new protection measures for Hector’s dolphin. Aquatic Conservation: Marine and Freshwater Ecosystems 20: 334–347.

Slooten E. 1991. Age, growth and reproduction in Hector’s dolphins. Canadian Journal of Zoology 69: 1689-1700

Slooten E. 2007. Conservation management in the face of uncertainty: Effectiveness of four options for managing Hector’s dolphin bycatch. Endangered Species Research 3:169-179.

Slooten, E. and Lad, F. Population biology and conservation of Hector’s dolphin. Can J Zool 1991 69: 1701-1707.

Slooten, E., Dawson, S.M. and Rayment, W.J. 2004. Aerial surveys for coastal dolphins: Abundance of Hector’s dolphins off the South Island west coast, New Zealand. Marine Mammal Science 20: 447-490.

Smith, I. 2020. Pākehā Settlements in a Māori World: New Zealand Archaeology 1769–1860. Bridget Williams Books.

Turek, J., Slooten, E., Dawson, S., Rayment, W. and Turek, D. 2013. Distribution and abundance of Hector’s dolphins off Otago, New Zealand. New Zealand Journal of Marine and Freshwater Research 47: 181-191.

Webster T, Rayment W. 2008. Abundance estimate for Hector’s dolphins using Porpoise Bay. Report for Department of Conservation.


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