PROJECTS /
Project Summary
Aotearoa is home to the world’s smallest and rarest dolphins.
Groundbreaking science is revealing the secret lives of Hector’s and Māui dolphins, transforming how we protect these rare taonga.
By uncovering where they go, how they feed, and the risks they face, we’re challenging long-held assumptions about their world.
Photo Credit – Richard Robinson
Aotearoa New Zealand is home to Hector’s and Māui dolphins. Found only in NZ, the Māui is the world’s smallest and rarest marine dolphin. Recognisable by their rounded ‘Mickey Mouse ear’ dorsal fins and striking black, white and grey markings, these dolphins are unique taonga – but they are under serious threat.
With only an estimated 15,000 Hector’s dolphins and just ~54 Māui dolphins remaining, the stakes could not be higher. Both species face multiple risks including fishing bycatch, disease, boat strike,
Until recently, almost everything we knew about these dolphins came from boat-based observations of their surface behaviour during daylight. That left huge gaps in our understanding of their underwater lives – where they feed, how deep they dive, and how their movements put them at risk of entanglement in fishing gear or vessel interactions.
These gaps have significant implications. Current management strategies, including the government’s Threat Management Plan and Marine Mammal Sanctuaries, were based on the assumption that Hector’s and Māui dolphins mainly inhabit shallow coastal waters. But this new research shows their range is broader and their behaviours more complex – meaning existing protection may not go far enough.
Record-setting dives down to ~120m deep! Extraordinary for a 1.4m animal
Tagged dolphins swam up to 15km offshore, well beyond current sanctuary boundaries.
Hectors dolphins were tagged with suction cup DTAGS as part of this study
Record-setting dives down to ~120m deep! Extraordinary for a 1.4m animal
Tagged dolphins swam up to 15km offshore, well beyond current sanctuary boundaries.
Hectors dolphins were tagged with suction cup DTAGS as part of this study
A breakthrough came with the use of DTAGs – high-tech, suction-cup devices that record sound, location, depth, speed, and 3D movements. Developed by Professor Mark Johnson, the tags were successfully deployed on 11 Hector’s dolphins in the Clifford and Cloudy Bay Marine Mammal Sanctuary.
The results, published in September 2025, revealed a hidden world of dolphin acrobatics and surprising behaviours:
Animations combining dive data and echolocation soundtracks have been created, offering the most vivid look yet at how Hector’s dolphins navigate their underwater world.
Rochelle Constantine
Professor – University of Auckland
“Despite this being a preliminary study, we can clearly see the value of the DTAG for understanding risks such as interactions with fishing gear or vessels,” says Professor Rochelle Constantine of Waipapa Taumata Rau – University of Auckland. “It’s important to continue this work to better understand how to minimise the risks to the dolphins and to know how they behave in other locations.”
The fine-scale analysis, supported by Live Ocean, the Bethell Family Foundation, the Department of Conservation, the Ministry for Primary Industries, Cawthron Institute and the University of Auckland, has already challenged assumptions underpinning current protection zones. Static sanctuaries may not align with where and how these dolphins are actually living.
The work in Cloudy Bay is only the beginning. To understand whether these behaviours are consistent across populations, further DTAG studies are needed in other high-risk areas such as Timaru and Kaikōura.
Scientific knowledge is a powerful lever. By uncovering the hidden lives of Hector’s and Māui dolphins, we can design smarter conservation strategies that balance industry and risk to wildlife – ensuring these rare and remarkable dolphins have a fighting chance for the future.
The West Coast North Island population of Hector’s dolphin is formally described as a new sub-species called Māui dolphin, Cephalorhynchus hectori maui.
Set-net controls to protect Māui dolphins were introduced by the Ministry of Fisheries on the west coast of the North Island
The Hector’s and Māui’s Dolphin Threat Management Plan (TMP) developed by DOC and the Ministry of Fisheries. Its purpose is to recognise human-caused threats to Hector’s and Māui dolphin and to come up with strategies to minimise or remove the threats. The TMP also sets out to identify research and monitoring to help Hector’s and Māui dolphin.
DOC moved to using genetic methods to do abundance estimates for Maui dolphins.
View the latest estimates here.
Increase in protection along the coastline as an outcome of the revised Threat Management Plan.
Toxoplasmosis Action Plan is released. The Threat Management Plan recognises the parasite Toxoplasma gondii, and the disease it causes, toxoplasmosis, as probably the largest non-fisheries threat to the dolphins. Toxoplasmosis is spread through the faeces of cats.
Research conducted in the Clifford and Cloudy Bay Marine Mammal Sanctuary, sound and movement recording devices called DTAGs, developed by New Zealand-based Professor Mark Johnson, were attached to 11 Hector’s dolphins using suction cups.
With support from Live Ocean and others, fine-scale analysis of the 2023 DTAG research data is completed and the results are published in September 2025.
Professor, UNIVERSITY OF AUCKLAND
Rochelle Constantine is a Professor in Marine Ecology and Conservation Biology at the University of Auckland – Waipapa Taumata Rau. Her research focuses on conservation threats and community interactions facing large marine animals. She works with a wide range of clever people using multi-disciplinary approaches to answer questions about the ocean. Rochelle leads international and New Zealand based programmes bringing countries and communities together to protect some of the most vulnerable animals. She was awarded an ONZM for her work and is a BLAKE Environmental Leader.
Professor, University of Auckland
Mark is an electronics engineer who develops instruments and data processing techniques for studying animals in the wild. These include miniature data-logging tags, such as the DTAG, that record sound and movement of animals from whales to bats, as well as sound recorders to detect the presence of vocal animals. To support these devices, Mark has developed widely-used computational methods for processing on-animal acceleration, magnetometry and sound data with a focus on sensory ecology and foraging. Formerly at Aarhus University, Denmark, he is now an honorary professor at the University of Auckland – Waipapa Taumata Rau.
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