Marlborough Sounds and Cook Strait IMMA

Size in Square Kilometres

22,403 km2

Qualifying Species and Criteria

Antarctic blue whale – Balaenoptera musculus intermedia 

Criterion A; C (3)

Arnoux’s beaked whale – Berardius arnuxii

Criterion C (2)

Cuvier’s beaked whale – Ziphius cavirostris

Criterion C (2)

Dusky dolphin – Lagenorhynchus obscurus

Criterion C (2)

Gray’s beaked whale – Mesoplodon grayi

Criterion C (2)

Hector’s dolphin – Cephalorhynchus hectori

Criterion A

Humpback whale – Megaptera novaeangliae

Criterion A; C (3)

Killer whale – Orcinus orca

Criterion C (3)

New Zealand fur seal – Arctocephalus forsteri

Criterion C (1; 2)

New Zealand sea lion – Phocarctos hookeri

Criterion A

Pygmy blue whale – Balaenoptera musculus brevicauda

Criterion A; C (3)

Sei whale – Balaenoptera borealis

Criterion A

Southern right whale – Eubalaena australis

Criterion C (3)

Sperm whale – Physeter macrocephalus

Criterion A; C (2; 3)

Marine Mammal Diversity 

Mesoplodon bowdoini, Balaenoptera bonaerensis, Tursiops truncatus, Delphinus delphis, Pseudorca crassidens, Balaenoptera physalus, Hydrurga leptonyx, Globicephala melas, Kogia breviceps, Mirounga leonina, Lissodelphis peronii

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The Marlborough Sounds and Cook Strait IMMA supports a large number of marine mammals, including seven threatened species including the Critically Endangered Antarctic blue whale; Endangered Hector’s dolphin, New Zealand sea lion, pygmy blue whale, humpback whale (Oceania sub-population), and sei whale; and the Vulnerable sperm whale. The region has nationally and internationally important sites for dusky dolphins (e.g. culturally important cooperative feeding in Admiralty Bay; Hector’s dolphins (e.g. distinct sub-population in Cloudy/Clifford Bay and Queen Charlotte Sound); forms an important migratory route for humpback whales; and is important deep water habitat for sperm, beaked and other teuthophagous whale species and coastal delphinids. The area has among the highest rates of pinniped bycatch in New Zealand, consisting mainly of New Zealand fur seals from local breeding colonies.

Description of Qualifying Criteria

Criterion A – Species or Population Vulnerability

There are seven species or subspecies found in the IMMA that meet this criterion with IUCN threatened or vulnerable status and include Antarctic blue whales (CR), Hector’s dolphins (EN), New Zealand sea lion (EN), pygmy blue whale (EN), humpback whale (Oceania sub-population; EN), sei whale (EN), sperm whale (VU) (Douglas et al. 2018). 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 and the wider region. Predominantly this IMMA forms an important feeding area for a range of marine mammal species with the high current Cook Strait area being an important source and also the western reaches of Cook Strait include important deep-water feeding habitats. In addition the IMMA includes a distinct subpopulation of threatened Hector’s dolphins centred around Cloudy/Clifford Bay (e.g. ~900 individuals) with a smaller group also found within Queen Charlotte Sound (e.g. ~50 individuals, Douglas et al. 2018, MacKenzie & Clement 2014).

Criterion C: Key Life Cycle Activities

Sub-criterion C1: Reproductive Areas

Important New Zealand fur seal breeding colonies (e.g. Cape Campbell, The Brothers, Stephens Island, Cape Palliser) occur along the Cook Strait Coastline of both the North and South Islands (Taylor et al. 1995) whose coastal and offshore feeding (particularly for nursing females) are constrained to area restricted foraging completely within the IMMA during the breeding season (MPI 2017).

Sub-criterion C2: Feeding Areas

Important New Zealand fur seal breeding colonies (e.g. Cape Campbell, The Brothers, Stephens Island, Red Rocks, Cape Palliser) occur along the Cook Strait Coastline of both the North and South Islands (Taylor et al. 1995) whose coastal and offshore feeding (particularly for nursing females) are constrained to feeding completely within the IMMA during the breeding season (MPI 2017). The IMMA includes a nationally and internationally important site for dusky dolphins including culturally important cooperative feeding in Admiralty Bay (Würsig & Würsig 2009). Arnoux’s, Cuvier’s, and Gray’s beaked whales, and sperm whales have been recorded from sightings, strandings (including with full stomachs) and acoustic surveys particularly within the deep water eastern reaches of Cook Strait highly with data likely to be indicative of important feeding areas (Gaskin 1968, Goetz and Hupman 2017, Giorli et al. 2018, Giorli and Goetz 2019, New Zealand DOC Marine Mammal Sighting and Stranding database 2020).

Sub-criterion C3: Migration Routes

Historical whaling data confirms this IMMA as an important migration route for humpback whales (Dawbin 1956), sperm whales (Gaskin 1968, 1970, 1973) and southern right whales (Richards et al. 2009, Carroll et al. 2014). Recent records, including satellite tracking of blue whales, have also confirmed that this IMMA still contains important migratory pathways for humpback, southern right whales, and blue whales (Bott et al. 2017, Carroll et al. 2013, Goetz et al. 2018, Warren et al. 2021).

Supporting Information

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.

Bentley, J., Bishop, S., Marshall, A., McAuslan, B., Murray, C., Lucas, D., Baxter, A., McRae, S., Courtney, S., Rutledge, M., Clayton Greene, J., Duffy, C., Walls, G., Lynn, I., and McCahon, S. (2014). Natural Character of the Marlborough Coast: Defining and mapping the Marlborough Coastal Environment. Co-ordinated by Boffa Miskell and Lucas Associates for Marlborough District Council and Department of Conservation. 321 p.

Bott, N., Dunlop, R., Gibbs, J., Heberly, J. and Olavarria, C. 2017. The potential beginning of a post-whaling recovery in New Zealand humpback whales (Megaptera novaeangliae). Marine Mammal Science 34(2) 499-513.

Cross, C. 2019 Spatial ecology of delphinids in Queen Charlotte Sound, New Zealand: Implications for conservation management. Unpublished PhD thesis. Massey University. 278 p.

Douglas, L., Childerhouse, S., Baxter, A., and Burns, D. 2018. Technical review: marine mammals in the Marlborough Sounds and impacts of marine mammal watching on these species. Report prepared for Department of Conservation by Blue Planet Marine. 101 pp.

Gaskin, D.E. 1968. Analysis of Sightings and Catches of Sperm Whales (Physeter Catodon L.) in the Cook Strait Area of New Zealand in 1963–4. New Zealand Journal of Marine and Freshwater Research 2(2): 260–272

Gaskin, D.E. 1970. Composition of Schools of Sperm Whales Physeter Catodon Linn. East of New Zealand. New Zealand Journal of Marine and Freshwater Research 4(4): 456–471

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

Giorli, G. and Goetz, K. 2019. Foraging activity of sperm whales (Physeter macrocephalus) off the east coast of New Zealand. Scientific Reports 9: 12182.

Giorli, G., Goetz, K.T., Delarue, J., Maxner, E.E., Kowarski, K.A., Martin, S.B. and McPherson C. 2018. Unknown beaked whale echolocation signals recorded off eastern New Zealand. Journal of the Acoustical Society of America. 143.

Goetz, K. and Hupman, K. 2017. Passive Acoustic Monitoring in the greater Cook Strait region with particular focus on Queen Charlotte Sound / Tōtaranui. Report prepared for the Marlborough District Council. National Institute of Water & Atmospheric Research Ltd. 150 p.

Markowitz, T.M., Harlin, A.D., Würsig, B., and Mcfadden, C.J. 2004. Dusky dolphin foraging habitat: overlap with aquaculture in New Zealand. Aquatic Conservation: Marine and Freshwater Ecosystems 14: 133–149.

Marlborough District Council (MDC) 2014. Proposed Marlborough Environment Plan. Available at

Merriman, M.G., Markowitz, T.M., Harlin-Cognato, A.D., and Stockin, K.A. 2009. Bottlenose dolphin (Tursiops truncatus) abundance, site fidelity, and group dynamics in the Marlborough Sounds, New Zealand. Aquatic Mammals 35(4) 511-522.

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.

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 Accessed in June 2020.

NZ Government 2008. Marine Mammal (Clifford and Cloudy Bay Sanctuary) Notice 2008. NZ Government Regulation 2008/329.

Protected Species Database 2019. Protected species captures, 2002–03 to 2017–18. Summary of observed and estimated total captures of seabirds, marine mammals and turtles in New Zealand trawl, longline, and set net fisheries. Online database managed by Dragonfly Science, Wellington, New Zealand. Available at:

Taylor, R.H., Barton, K.J., Wilson, P.R., Thomas, B.W. and Karl, B.J. 1995. Population status and breeding of New Zealand fur seals (Arctocephalus forsteri) in the Nelson‐northern Marlborough region, 1991–94. New Zealand Journal of Marine and Freshwater Research 29(2): 223-234.

Thompson, F.N., Abraham, E.R., and Oliver M.D. 2010. Estimation of fur seal bycatch in New Zealand trawl fisheries, 2002–03 to 2007–08. New Zealand Aquatic Environment and Biodiversity Report No. 56. 29 p.

Warren VE, Sirovic A, McPherson C, Goetz KT, Radford CA, Constantine R 2021. Passive Acoustic Monitoring Reveals Spatio-Temporal Distributions of Antarctic and Pygmy Blue Whales Around Central New Zealand. Frontiers in Marine Science 7. article 575257

Wursig, B. and Wursig, M. (eds.) 2010. The Dusky Dolphin: Master Acrobat Off Different Shores. Academic Press. 441 p.


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