Cetaceans Around Aotea/Great Barrier Island 

BARRY SCOTT interviews SARAH DWYER and KIRSTY PRIOR (Department of Conservation, Aotea Great Barrier Island)

Can you give us some background on how you got involved with the conservation of cetaceans? 

Sarah 

While I’ve had a passion for ecology since a young age, I got more seriously involved in marine conservation during my PhD study on “The Spatial Ecology and Conservation of Cetaceans in the Hauraki Gulf”. Initially my work was confined to the inner Gulf but later included the outer Gulf around Aotea/Great Barrier Island where to my surprise no cetacean surveys had been previously carried out. Weather permitting, I spent 3-4 days each month during 2011 and 2012 off the west coast of Aotea constantly scanning the ocean. By the end of a 3-year survey period I had clocked up over 20,000 km of survey effort in Tikapa Moana/Te Moananui ā Toi/Hauraki Gulf studying whales and dolphins. My most exciting find was the discovery of a ‘semi-permanent’ population of bottlenose dolphin/terehu (Tursiops truncatus) around Aotea. I used a technique called photo-identification where I collected photos of the unique dorsal fins to track individuals. All of the ~ 170 dolphins recorded at Aotea were also sighted in neighbouring regions such as the Bay of Islands or Bay of Plenty, so while they appear to spend a lot of time around Aotea, they do also move a lot up and down the coast.

Olivia Hamilton discusses the importance of Aotea for North Island bottlenose dolphins in Issue 46 of Environmental News. In contrast to the common dolphin/popokanua (Delphinus delphis), which spend most of their time in deeper waters but come closer to shore in the colder months, the bottlenose dolphins spend most of their time close to the coast. Here on Aotea we are super lucky that we can spot several cetaceans species from many places around the coast without stepping off dry land! 

Kirsty 

Like Sarah I am also passionate about the marine environment and I love the ocean. One of my key roles in my current position as Operations Manager for DOC on Aotea is to bring the right minds together and pull out the information we need to make robust decisions. The Department receives applications for a host of activities under various legislation. In relation to cetaceans, the most common applications come from researchers, film makers and occasionally tourism operators. The activities range from approaching species closely on vessels, in water interactions, or aerial photography. Each permit is considered carefully. Scientific advice and iwi consultation are important parts of the decision making process. 

Are you (Sarah) still involved in studying cetaceans since moving to full-time employment with DOC on Aotea since 2017? 

Sarah 

Since taking up employment with DOC my work has become much more general, but I do maintain links with colleagues at Massey University and am a Trustee with the Far Out Ocean Research Collective(1). We are a group of scientists passionate about the marine environment and in particular learning more about whales and dolphins offshore where few people go. As a group we have carried out several deep-water surveys around sea canyons and seamounts. One of our most interesting findings is the co-operative hunting among false killer whales (Pseudorca crassidens), pelagic bottlenose dolphins/terehu (Tursiops truncatus) and black petrels/tāiko (Procellaria parkinsoni). Bottlenose dolphins appear to lead the hunt when the prey is kahawai/kōukauka (Arripis trutta) whereas the false killer whales take that lead role when schools of kingfish/haku (Seriola lalandi) are present. Black petrels feed on the leftovers of these ‘hunts’. We have camera footage of this very interesting cooperative behaviour from cameras mounted on suction cups on the backs of the whales (despite the name, false killer whales are actually dolphins). There is also some wonderful footage of false killer whales off the back of Aotea that featured on Blue Planet 2(2). I feel privileged to be involved in the DOC work that supports the black petrels when they are land-based here on Aotea and then observe their behaviours while they are at sea interacting with cetaceans. I’ve also set up a citizen science project on iNaturalist called Maha taonga o Aotea to try to connect people with the amazing marine mammals around our shores(3). Like Kirsty I’m interested in all things marine and can often be found down at Whangapoua estuary with my kids searching for marine critters!

WHAT ARE YOUR FAVOURITE MARINE MAMMALS?

Sarah 

If I had to choose only one species (which is very difficult as they are all amazing!), probably the false killer whales (Pseudorca crassidens) that are so unique and to this day we still don’t know where they go when they are not in New Zealand coastal waters between June and November so if you see them please call 0800 FAR OUT. There are other fascinating less frequent visitors to the oceans and bays around Aotea such as the killer whale/orca (Orcinus orca), humpback whale/paikea (Megaptera novaeangliae), and blue whale (Balaenoptera muscuus). Whenever I hear that one of these species is in the vicinity, I race down to Port Fitzroy to observe from shore or boat out to sea to watch and record the behaviour of these wonderful creatures of the ocean. Of course, for their safety (and ours) we need to know, and stick to, the rules and regulations(4). 

The coastal orcas are constantly on the move and often cover up to 150 km per day feeding on rays and sharks. The humpbacks that pass by Aotea are usually moving between their summer feeding grounds in Antarctica and the winter calving and breeding grounds in tropical waters. Most pass through Cook Strait but some travel along the east coast. The blue whale is a less frequent visitor but is occasionally sighted in the Gulf in the triangle circumscribed by Te Hauturu-ō-Toi/Little Barrier Island, Mokohinau Islands and Aotea/Great Barrier, which is a productivity hot spot in the outer Gulf(5). There is also the pygmy blue whale (Balaenoptera musculus brevicauda), which is a smaller sub-species of the blue whale but looks almost identical. It has a distinctive sound that distinguishes it from the blue whale. We know very little about their population numbers and what they feed on while in the Gulf. 

Kirsty 

I agree with Sarah that all marine mammals are incredible. While it’s a bit mainstream, I do love dolphins. They’re such excitable, intelligent and social creatures that you can’t help but scream with excitement and smile when you see them. As a surfer of 30 years, I’ve had some amazing interactions over the years and I can certainly see why you need to keep a respectful distance, as a one tonne blubber bullet flying through the air can cause some serious damage! 

Near Aotea’s shores we also see Brydes (pronounced broo-dus) whales, which I always think of as elusive, private types. The Hauraki Gulf is home to a resident population of these ocean giants with about 50 individuals that almost exclusively use the Gulf, and about an-other 100 that pop in and out. Last summer we had a Bryde’s whale blow a bubble curtain underwater which brought up a wall of bubbles to the surface. This is a technique they use to disorientate and manoeuvre prey during feeding. While not a cetacean or mammal, just off the west coast of Aotea is Aotearoa’s oceanic manta ray hotspot. Searching for mantas and accidentally finding marine mammals makes for epic summer days. 

New technologies must be having a big impact on your ability to study the behaviour of cetaceans? 

Sarah & Kirsty 

Probably the biggest technological advancement that has helped study behaviour has come from the use of drones. These have been a game changer world-wide in studying the behaviour of marine mammals. While drones can provide a terrific visual perspective of population behaviour, you can only ID individuals by being on boats to capture images of dorsal fins. There are also some amazing AI tools that can be employed through drones to identify with high probability the species in the ocean. Internationally, researchers are using drones, affectionately named ‘Snotbots’ to collect samples from a whale’s blow. So there is some terrific technology that has dramatically improved our knowledge of these marine species. 

These new technologies can also be a new threat or risk that needs to be managed, and the legislation is often unable to keep up with the rate of change with technology. For example, drone use around marine mammals is regulated as per other aircraft and a permit is required to deviate from that. The current regulations require drones to be 150m from any marine mammal. More guidance can be found on the DOC website(6). 

What is the role of DOC in protecting cetaceans? 

Kirsty 

While there are several bodies, including Auckland Council and Ministry for Primary Industries (MPI), involved in protecting the habitat and marine fauna in the Gulf, DOC has a very specific regulatory role under the Marine Mammals Protection Act (1978), which provides for the conservation, protection, and management of marine mammals(7). A permit is required for anyone to ‘take’ (kill, injure, harass, disturb etc) a marine mammal but this regulation also applies to any ‘intervention’ such as might be involved with marine research. The Act also provides for the establishment of marine mammal sanctuaries, of which there are just seven in New Zealand, with none in the greater Gulf area. We also administer the Marine Mammals Protection Regulations (1992), which were developed to manage whale and dolphin watching tourism(7). Commercial tourism of this kind is not large in the Gulf but it may grow. However, there is quite a lot of commercial filming (e.g. BBC) where a permit is also required. Once issued it is our job to ensure there is compliance with those permits. Moratoriums can be placed on marine mammal tourism in certain areas to restrict the number of commercial operators with permits and keep the impact on the animals lower. 

The Marine Mammal Regulations also provide rules on how the general public should behave around marine mammals when on the water to reduce the risk of stress or injury. For example, you should slow down to five knots within 300 m of any marine mammal and there should only be three boats in this vicinity at one time. The rules are stricter for whales (including orca and pilot whales) which keeps both us and the animals safe. In these cases, you must not approach within 50 m or swim with the animals. Other regulations to know about when on the water can be found on the DOC website(8), or contact marine@doc.govt.nz for a brochure, poster, or sticker. 

Voluntary protocols are also a great way to protect the marine fauna. Scientific research by the University of Auckland showed that Brydes whales spend 90% of their time within 12 m of the surface making them vulnerable to vessel strike from ships entering and leaving the Gulf. Research overseas had shown that ship strikes on the Northern Atlantic Right Whale off the eastern seaboard of the USA and Canada was successfully reduced through establishment of speed restrictions and establishment of vessel avoidance areas. The latter was not seen as a practical solution in the Gulf as the small population of Brydes whales, estimated at less than 200 individuals, are distributed throughout. So the most effective means of reducing strikes was identified as being a reduction in the speed of vessels. With the cooperation of several bodies a Voluntary Protocol was established in 2013 with three key elements(9): (i) a reduction of vessel speed to 10 knots whilst in the Gulf, (ii) keeping a watch for whales with binoculars and (iii) reporting any sightings of whales to the Harbour master. There have been no known whale strikes within the Gulf since that time. This is a great example of the importance of research informing specific protective measures and collaboration. 

Sarah 

We are also responsible for dealing with beached whales. We work closely with Project Jonah and at least 30 people on the island are trained on how to respond to marine mammal strandings. Given marine mammals are precious taonga there is very close engagement with mana whenua to ensure all strandings follow strict tikanga protocols. There are differEnt protocols for different species so it is really important to have that close relationship with iwi. There have been three major mass strand-ing events in recent times, including ~13 sperm whales at Okupu in 1972(10), ~400 pilot whales at Kawa in 1985(11) and nine Gray’s beaked whales at Whangaparapara in 2020. But there have also been a number of single whale beachings, including a pygmy sperm whale at Okupu in 2017, a Brydes whale at Awana in 2003 and a Brydes whale at Okupu in 1986.We hear a lot about the dire state of the ecological health of the Hauraki Gulf. 

What are the major threats to Cetaceans in the Gulf? 

Kirsty & Sarah 

Probably the biggest threat to cetaceans in the Gulf are humans and their activities. Availability of sufficient food is crucial for maintaining viable whale and dolphin populations even if the Gulf is just a stopover point for mammals passing through. While we have a lot of information on what species they eat and where they occur(12), there are some major knowledge gaps on population levels of species such as anchovies and pilchards, which are the staple of many of these cetaceans(13). Talk to any old fishermen around the Gulf and they will tell you there has been a dramatic decline. Climate change is one of the biggest threats with a lot of uncertainty as to what the future will look like. The warmer seas will not be favourable for some of the current species, but we may see increased numbers of species that favour these warmer temperatures. Microplastics are a relatively new but very important issue for marine mammals. One study has shown that there were four times the levels of microplastics in the whale gut compared to the sea environment because of the accumulation effect of the different trophic levels of feeding(14). 

Another issue we are just beginning to under-stand is the disruption to the behaviour of marine fauna in response to noise. There is a growing body of evidence showing that vessel noise is highly invasive and audible to nearly all marine animals including fish. The two-month nation-wide lockdown provided scientists with a unique opportunity to study how human activity may affect wildlife. Dr Craig Radford (University of Auckland) and colleague Matthew Pine (University of Victoria, Canada), used this ‘silent’ window of opportunity to investigate the impact of vessel noise on the behaviour of bottlenose dolphins in the Gulf(15). This study generated strong evidence that small vessels, where there are so many of them in the Gulf, directly affect sound levels in the ocean, and have an impact on dolphin behaviour(16). The quieter noise levels meant that the communication range for dolphins more than doubled. There is also the problem of boatie behaviour such as bringing their boats too close to marine mammals or engaging in reckless behaviour such as driving their boats through a pod of dolphins(17),(18). While we need a licence to drive a car that is not the case with a boat so a lot more work needs to be done educating boaties about how they can minimise their impact on marine fauna, especially within the Gulf, and how they might help to protect it. A lot of different tools are needed to protect the marine environment and sometimes it just takes time for the appropriate legislation or regulations to be enacted by Parliament. Great-er education of the public and self-regulation are important ways we can help. 

How do you think AGBET can help? 

Sarah 

One of the key ways you can help is to promote the use of iNaturalist. This is much better than reporting on the Barrier Chit Chat Facebook site. In iNaturalist you immediately become connected with experts throughout the world and the post becomes a permanent record for others to refer to. It can serve as a one stop shop or clearing house for information on our local environment. Two good examples of postings recently that generated quick responses were the reports of myrtle rust on pohutakawa in Tryphena and Caulerpa brachypus in the sea at Okupu. If the community posts observations of cetaceans on iNaturalist, such as a photo of a fin, there will be fast feedback of what the species is and possibly even which population it belongs to. This citizen science is so important for conservation. Many of the locals on the island are well connected with the environment and are very observant. Tapping into that local knowledge would help fill many of the gaps that we (DOC) are unable to cover. 

It's also great to see the increased focus on the plight of our marine waters as so often what is out of sight is out of mind. Keep up the good coverage in your newsletters of what’s happening in our marine environments. 

Kirsty 

Becoming familiar with the marine mammal regulations and sharing our coasts responsibly will allow us all to enjoy our waters safely and thrive. Let marine mammals choose how they want to interact with you, rather than forcing it on them which can interrupt important behaviours such as socialising, feeding, and resting. Share the message to let others know the rules and report anyone seen harassing animals. Call 0800DOCHOT to report harassment or injured or stranded animals. 

References:

1. www.farout.org.nz

2. https://en.wikipedia.org/wiki/Blue_Planet_II. Episode 1 of Blue Planet II, a nature documentary series on marine life produced by the BBC Natural History Unit, which is narrated and presented by naturalist Sir David Attenborough

3. https://www.inaturalist.org/projects/maha-taonga-o-aotea. INaturalist NZ. 

4. https://www.doc.govt.nz/nature/native-animals/marine-mammals/sharing-our-coasts-with-marine-mammals/ 

5. Hamilton, Olivia (2022). The importance of the Aotea marine environment to the Gulf’s marine meagafauna community. Environmental News Issue no. 46, winter 2022. 

6. https://www.doc.govt.nz/get-involved/apply-for-permits/drone-use-on-conservation-land/flying-drones-near-marine-mammals 

7. Department of Conservation. Marine mammal conservation https://www.doc.govt.nz/about-us/our-role/managing-conservation/marine-mammal-conservation/ 

8. https://www.doc.govt.nz/nature/native-animals/marine-mammals/sharing-our-coasts-with-marine-mammals/ 

9. Environment Foundation. Case study: Bryde’s whale voluntary protocol for shipping in the Hauraki Gulf. https:// https://www.environmentguide.org.nz/issues/marine/vessels/case-study-brydes-whale-voluntary-protocol/ 

10. Armitage, D 1972. Sperm whale beaching. https://sites.google.com/a/aotea.org/don-armitage/Home/great-barrier-island-fauna--flora/cetaceans-whales--dolphins/sperm-whale-stranding-blind-bay-1972/photos-by-les-and-beverley-blackwell

11. Te Ara. Encyclopedia of New Zealand. Saving stranded whales. https://teara.govt.nz/en/video/7109/saving-stranded-whales 

12. Kozmian-Ledward L, Jeffs, A and Gaskin C (2020). Report prepared for the Department of Conservation. Fish shoal dynamics in the North-Eastern New Zealand POP2019-02. Milestone 5: Final report summarising analysis of zooplankton samples collected 2019-2020. 

13. The State of the Gulf Report 2020. https://gulfjournal.org.nz/state-of-the-gulf/

14. Zantis LJ, Bosker T, Lawler F, Nelms SE, O’Rorke R, Constantine R, Sewell M and Carroll EL (2022). Assessing microplastic exposure of large marine filter-feeders. Science of the Total Environment 818: 151815. 

15. Williams C (2021). Lockdown study of Hauraki Gulf shows dolphins communicate better with fewer boats. https://www.stuff.co.nz/environment/300363802/lockdown-study-of-hauraki-gulf-shows-dolphins-communicate-better-with-fewer-boats

16. Pine MK, Wilson L, Jeffs AG, McWhinnie L, Juanes F, Scuderi A & Radford CA (2021). A Gulf in lockdown: how an enforced ban on recreational vessels increased dolphin and fish communication ranges. Global Change Biology. https://doi.org/10.1111/gcb.15789 

17. https://www.stuff.co.nz/auckland/local-news/rodney-times/91246220/boaties-given-formal-warning-for-driving-over-pod-of-dolphins 

18. https://www.nzherald.co.nz/nz/doc-investigating-video-of-jet-ski-driving-through-dolphin-pod/4IMIOHTV7CPWTO324UFDFIVSOU/