A status report on the critically endangered Māui dolphin.

Environment | Oceans

By Julia Riopelle, Co-Editor in Chief

Published March 18, 2021

Two of the world’s smallest dolphins have been listed as endangered and critically endangered by the International Union for Conservation of Nature (IUCN). The populations of Hector’s and Māui dolphins are dwindling, with only around 10,000 Hector’s and a mere 63 Māui dolphins, respectively.

The IUCN, IWC Scientific Committee, WWF and a multitude of New Zealand-based conservation groups are calling for stricter measures to be set in place for the protection of the two dolphin species. If immediate action is not taken soon, the Māui dolphin will be extinct in less than a decade, with the Hector dolphin soon following suit.

Hector’s and Māui dolphins are endemic to New Zealand waters, meaning it is the only place in the world where they can be found. The two black and white dolphins appear identical, standing out with a uniquely rounded dorsal fin, however their genetic differences classify them as two separate species.

The small population of Māui dolphins can be found on the west coast of the North Island of New Zealand, between Maunganui Bluff and Whanganui. They live in shallow waters, which are usually no more than 20 meters deep. The Hector’s dolphins, on the other hand, are more widespread, living off the coasts of both the North and South Islands of New Zealand.

Pod of Māui dolphins in New Zealand. | Colin Haycock / Flickr

Why are there only 63 Māui dolphins left?

Since the widespread introduction of gillnets in the 1970s and the increased trawling in the 1980s, the Māui dolphin population has diminished from 1500 individuals to the 63 claimed to exist today – a number that itself could in reality be much lower. Currently, numbers of Hector’s dolphins are thought to only be one-fifth of the 50,000 individuals present in the 1970s.

The main threat to these endemic dolphins, as well as many other cetaceans around the world, is becoming a by-catch of fisheries. By-catch is defined as all non-target species caught in a fishing catch. This occurs because cetaceans are also after fish, so when many fish are being caught in the net that fishermen set, it naturally attracts the predators of those fish as well.

Fisheries use many different methods to catch seafood; drift sets are placed near the sea surface on currents, gillnets are suspended between the sea surface and the seabed, and set nets are fastened to the seafloor to catch demersal fish. Another more destructive method of fishing is previously-mentioned trawling, where a ship drags a large weighted net along the bottom of the ocean.

What’s the problem with these fishing practices?

Most fishing practices are non-specific, meaning they catch anything and everything that happens to be in the way of the nets. Trawling causes severe habitat destruction along the bottom of the ocean. The dragging of the heavy-chained nets not only catches fish, but all other species that reside on the ocean floor, sediments, corals, sponges and more.

Furthermore, nets cannot be detected via echolocation, a sound-based method of navigation used by cetaceans and therefore causing them to be at high risk of being caught in the nets. Studies have found that gillnetting and trawling have caused the highest rates of by-catch, and set nets have been directly linked to 58% of Hector’s and Māui dolphin deaths.

In a 20-year period (1998 to 2018), the New Zealand government determined that 107 of 317 reported Hector dolphin deaths were a result of entanglement. For a further 126 Hector dolphins, the cause of death could not be determined. In the same period, five of twenty reported Māui dolphin deaths were due to entanglement, whilst they could not determine the cause of death for a further seven.

Commercial fishing netting. | Paul Einerhand / Unsplash

Why are cetaceans specifically vulnerable?

An additional issue is that cetaceans, such as the Hector’s and Māui dolphins, are described as ‘k-selected species.’ These are species that generally have stable populations, slower rates of maturity, lower numbers of offspring and higher investment in parental care. Examples of such are whales, dolphins, elephants, humans, etc. The opposite ‘living strategy’ of animals are ‘r-selected species’, who have quicker rates of maturity, high numbers of offspring, quick population turnovers and little parental care.

As k-selected species, female Māui dolphins first reproduce at seven to nine years of age, and only reproduce every two to four years. The population growth of the two dolphin species is very slow, and so any reduction in numbers is hard for the population to recover – especially if the individual dies before reaching sexual maturity.

Cetaceans are highly social, intelligent mammals with a complex population structure. Pods of dolphins and whales tend to include ‘key individuals’, such as a leading matriarch or perhaps an individual that links different population groups. If you remove one of these key individuals from a population, then the whole social dynamic can fall apart.

What actions have been proposed to protect the critically endangered Māui dolphin?

A recent 2020 proposal, aimed to protect the remaining dolphin populations, has urged the government of New Zealand to extend and create new areas to prohibit the use of commercial and recreational set nets in North and South Island. It specifically called for the prohibition of trawling in central Maui, where the 63 Māui dolphins live, as well as the use of drift nets in all New Zealand waters.

Most areas where Māui dolphins live already have set net and trawling bans, however their broader habitat extends into areas which do not (from Cape Reinga to Cape Egmont). Thus, new commercial and recreational set net restrictions were proposed in the following areas of the west coast of the North Island:

1. Four nautical miles offshore between Cape Reinga and Maunganui Bluff.

2. Four nautical miles offshore between Hawera and Wellington.

3. Two to seven nautical miles offshore between the Waiwhakaiho River in New Plymouth and Hawera.

4. Seven to twelve nautical miles between Maunganui Bluff and the Waiwhakaiho River in New Plymouth.

5. Extend the closures into the Manukau Harbour to Taumatarea Point and Matakawau Point.

6. Additionally, commercial trawling closures should be extended to between Maunganui Bluff and Pariokariwa Point.

Another vital change is that fishing policies need to limit fishing-related mortalities to zero dolphins within the Māui dolphin habitat zone. The by-catch limits placed on fisheries and other human activity are known as a ‘maximum sustainable yield’, which determines the number of animals which can be killed without driving a population towards extinction. As the Māui dolphin population is at a mere 63 adult individuals, the species cannot afford anymore ‘allowed’ deaths.

New set net and trawling restrictions of the North Island, New Zealand. | Julia Riopelle / The Kingfisher

What new measures have been approved and put into action by the New Zealand government?

Since the 1 October 2020, new fishing rules have been put into place in order to reduce the threats on Hector’s and Māui dolphins. In the central, Auckland and Kermadec fishing areas, set nets are largely prohibited and the ban on trawling has been further extended into the Māui dolphin habitat zone. The proposal was also successful in banning all drift nets in all fishing areas in New Zealand.

In terms of set nets, the Ministry for Primary Industries only implemented the proposals No.2, No.3 and No.4 from the list above. However, there are still no net restrictions between Cape Reinga and Maunganui Bluff, which is part of the greater habitat area of the Māui dolphin. Instead, they proposed the transition to ring-netting in these areas, which does not pose a risk to dolphins.

In addition, in the areas which do allow set nets, they must not be baited, exceed 60 meters in length or be set within 60 metres of another net. Securing nets with stakes have now also been banned and no fisherman may set or possess more than one set net.

The hope is that implementing these new suggestions will allow the Māui dolphin and Hector’s dolphin populations to increase to 95% carrying capacity of environment and 90% of carrying capacity of environment, respectively.

What do these new restrictions mean for New Zealand’s fishing industry?

Implementing these measures will likely cost commercial fishers NZ $5.58 million, as they will have costs for the purchasing of new gear and travelling to other areas where set nets are allowed. The monarchy will not pay compensation for these changes.

The new restrictions on the fishing industry should not have an effect on the ‘total allowable commercial catches’ per year, just in the ways and areas these are to be caught. However, until now, the waters in which the Hector and Māui dolphins reside, have brought in NZ $50 million per year.

It is also expected that these measures will cause a NZ $2.15 million revenue loss annually from set nets and NZ $1.82 million annual loss from the trawling bans. Economists estimated that a low impact on the economy after five years would be NZ $11.27 million from set nets and NZ $9.53 million from trawling. Whereas a high impact estimate is NZ $27.07 million from set nets and NZ $22.89 million from trawling after five years. One can therefore understand the oppositions that the implementation of these policies face, due to the security of many livelihoods that they threaten.

A particular group threatened by the new fishing restrictions are the indigenous Māori people. Fishing was a major trading industry between Māori communities before the arrival of European colonists. Having experienced years of exploitation and territory loss, it was only until the Treaty of Waitangi (1840), where the Māori gained full and undisputed claims over their fisheries.

Small fishing vessels. | Samule Sun/ Unsplash

However, as the guarantees ensured by this treaty continued to be breached, and indigenous people kept seeing their fisheries degraded and depleted of resources. Today, after centuries of fighting for rights and settlements, the Māori control around 30% of New Zealand’s commercial fisheries. The New Zealand Parliament also approved the distribution of fishery assets to the Māori, which has been overseen by the Te Ohu Kei Moana, a marine fishing organization which protects the rights of indigenous Māori people.

Now, the new regulations put in place to protect the Hector and Māui dolphins will affect at least five iwis (local Māori groups) in the North Island. Although there are many Māori who are open to altering their fishing practices in order to minimize the impacts on dolphins, there are twenty Māori-owned fishing companies on the West Coast which will take a major hit. Despite their good intentions toward dolphin conservation, the new laws undermine the fishing rights and compensations that the Māori had been previously promised.

The New Zealand government is currently revising a ‘transition package’ of approximately NZ $75,000, in order to support both Māori and other fishing businesses affected by the new changes. These will either be through a one-off payment to the most affected fisherman or funding to offset the transition costs for them to change to dolphin-friendly fishing methods. Nonetheless, short-term payments will not rectify the loss of security that they will face in their current livelihoods.

Hector’s Dolphin leaping out of New Zealand waters. | Roselyn Cugliari / Unsplash

What else is being done?

In order to reduce by-catch in fishing practices, localized solutions need to be created. One needs to first determine the scale of the impact, by assessing natural versus unnatural deaths of the Hector’s and Māui dolphins, as well as the size of the impacted population. Using this, one can then calculate the robustness of the population, which is the ability for the given population to absorb the impact. In the case of Hector’s dolphins, there may still be some leeway, however the Māui dolphin cannot allow any more human-induced deaths.

Some fisheries around the world have begun to install by-catch reduction devices in their trawl nets, which have shown to be able to decrease by-catch by up to 45%. These devices aim to prevent larger animals from drifting to the back of these nets, by having an escape hatch where the animals fall out. Although many of the cetaceans that fall out are injured or dead, the installment of an escape hatch has largely reduced the number of turtle by-catch.

Other devices have included acoustic deterrent devices, which are attached to nets and emit sounds which the dolphins can detect. The IWC Scientific Committee has called for the creation of safety corridors between the north and south populations of Hector’s dolphins, in order to allow for healthy gene flow.

However, if we want any hope for the survival of the Māui dolphins there need to be more immediate actions. Many are saying that the new restrictions are not enough, and that there needs to be a complete closure of all fishing in the Māui dolphin habitat area.

Featured Image: Mai Moeslund | Unsplash

Department of Conservation (2021) 'Facts about Māui dolphin.' New Zealand Government Available at: https://www.doc.govt.nz/nature/native-animals/marine-mammals/dolphins/maui-dolphin/facts/ [Accessed March 22nd 2021]

Fisheries New Zealand (2020) ‘Recreational Fishing Rules: Central.’ New Zealand Government. Available at: https://www.mpi.govt.nz/dmsdocument/7281-Central-Recreational-Fishing-Rules-printer-friendly [Accessed March 22nd 2021]

Ministry of Primary Industries (2020) ‘Central Area Fishing Rules.’ New Zealand Government. Available at: https://www.mpi.govt.nz/fishing-aquaculture/recreational-fishing/fishing-rules/central-area-fishing-rules/ [Accessed March 22nd 2021]

Ministry of Primary Industries (2020) ‘Auckland and Kermadec area fishing rules.’ New Zealand Government. Available at: https://www.mpi.govt.nz/fishing-aquaculture/recreational-fishing/fishing-rules/auckland-kermadec-fishing-rules/ [Accessed March 22nd 2021]

Office of the Minister of Fisheries (2021) Hectors and Māui Dolphin Threat Management Plan Review – Fisheries Measures. New Zealand Government.

Stats NZ (2019) ‘Bycatch of protected species: Hector’s and Māui dolphins.’ New Zealand Government. Available at: https://www.stats.govt.nz/indicators/bycatch-of-protected-species-hectors-and-maui-dolphins [Accessed March 22nd 2021]

Te Ohu Kaimoana (2021) ‘Responses to Government.’ Te Ohu Kaimoana. Available at: https://teohu.maori.nz/governance-reporting/responses/ [Accessed March 22nd 2021]

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