Female Māui dolphins grow to 1.7 m long and weigh up to 50 kg; males are slightly smaller and lighter.

The diet of Māui dolphins is poorly understood though is known to include ahuru, red codling and Peltorhamphus flatfish, based on the stomach contents of three dead individuals.

[31] The latest estimate of the Māui dolphin subspecies 2020–2021 is 54 individuals aged 1 year or older (1+) (95% confidence interval (CI) = 48–66), based on genetic capture-recapture data.

Sightings of this type of dolphin along the coast north of Wellington are infrequent, with the DOC database reporting only seven since 1970, though may suggest a more widespread and larger populations in the past.

[18] During the 2012/2013 summer, the DOC conducted five aircraft and six boat searches, between New Plymouth and Hāwera, without seeing any Māui or Hector's dolphins.

[39] Set nets are deemed to be the main commercial fishery threat to both Hector's and Māui dolphins, based on model estimates and the small sample of observed deaths.

[38][35] A total 15 deaths from all causes have been recorded along the west coast of the North Island, since the first major restrictions on commercial fishing to protect Māui dolphins were imposed in 2003.

[38] The single Hector's or Māui dolphin death attributed to fishing was captured in a set net off Cape Egmont, in Taranaki waters in January 2012.

Set netting is prohibited inside the entrances of the Kaipara, Manukau, and Raglan Harbours and Port Waikato.

Based on 2012 population estimates, the World Wildlife Fund in New Zealand launched "The Last 55" campaign in May 2014, calling for a full fishing ban over what it believed is their entire range.

[8][45][46] Some groups in the fishing industry are against increased bans on set nets into waters further offshore and inside harbours, and say other factors are responsible for low population size, including disease, pollution, mining, and natural predation.

The Toxoplasma oocysts are thought to be transmitted from cats to the coast via freshwater runoff, before working up the food chain and being ingested by the dolphins.

[6] The same assessment estimated that between 1-3 Hector's and Maui dolphins die each year off the West Coast of the North Island, based on an extrapolation from the necropsy-determined primary causes of death.

Brucellosis is a disease of terrestrial mammals that can cause late pregnancy abortion, which has been found in a range of cetacean species elsewhere,[48] and has been determined from necropsies to have been the primary cause of death of both Hector's and Māui dolphins.

[49][6] In June 2014, the government decided to open up 3,000 square kilometres (1,200 sq mi) of the West Coast North Island Marine Mammal Sanctuary — the main habitat of the Māui dolphin—for oil drilling.

[6] The low availability of key prey species may exacerbate the susceptibility of Māui dolphin to the effects of climate change.

[6] A new group named MAUI63 is utilising large drones and computer vision-based artificial intelligence with the hope to collect up-to-date location data.