Hector's and Maui's dolphins are a protected species under the Marine Mammal Protection Act 1978. The Department of Conservation (DoC) Threat Classification system ranks Maui dolphin as ‘nationally critical’, and Hector’s dolphin as ‘nationally endangered’.
Both subspecies are classified on the International Union for the Conservation of Nature (IUCN) Red List. Hector’s are listed as ‘endangered’, and Maui’s as ‘critically endangered’. This means that both species face extinction in the wild.
Human induced threats are the main problem for both species. Boat strike, mining, construction, coastal development, pollution, marine tourism, marine farming and climate change are all hugely dangerous for Hector’s and Maui’s. The biggest single known threat, however, is from fishing.
Fishing-related threats include entanglement in set nets, trawl nets, drift nets and crayfish pot lines. 188 Hector’s and Maui’s dolphins have been killed in set nets since 1973.
Maui dolphins are in a critical situation because their population is so small. As well as being slow breeders (a female has a single calf every 2 - 3 years) they only become sexually mature at a late age (about 7 - 9 years) and their pool of potential mates is very small, meaning that inbreeding may occur.
Inbreeding reduces the gene pool and creates a higher chance of birth defects and genetic problems.
In the 19th Century Maui dolphins were found around the North Island coastline, from Tuaroa Point in Northland to mid-Bay of Plenty. Sadly, they are now only found from Maunganui Bluff (near Dargaville) to just south of New Plymouth - most commonly between Manukau Harbour and Port Waikato. And as Maui dolphins prefer shallow waters, this brings them into direct contact with humans and makes them particularly vulnerable to their main threat: fishing.
Following intense lobbying by members of the public and groups like Project Jonah, the Government introduced a Threat Management Plan (TMP) in 2008. Among the measures introduced, was the establishment of marine mammal sanctuaries, and restrictions on set and trawl netting.
The Maui’s section of the TMP was reviewed in 2012 following the continued decline of the species, and another death as a result of set netting. The government implemented an interim set net ban between Pariokariwa Point and Harewa, out 2 nautical miles, short of the IWC and ICUN recommendations.
Whilst this particular ban zone was later extended, measures have not gone far enough. An estimated 110-150 dolphins are caught every year in set nets around New Zealand.
In 2018 the government began a review of the full Hectors and Maui TMP, with a formal public consultation scheduled for November-December.
The results of this review will be presented to Ministers in early 2019.
Around New Zealand dolphins continue to die as a result of set-netting. In February 2018 a pod of five Hector’s dolphins died after being caught in a set net 6 nautical miles off Banks Peninsula. To ensure the survival of both Hector’s and Maui’s dolphins, deaths from fishing must be zero.
To make matters worse, the government is stalling on its proposal to put cameras onto commercial fishing vessels. Cameras would ensure that set net and trawling restrictions are obeyed and bycatch of marine mammals is reported. Currently we rely only on verbal reports from fishermen.
For Maui dolphins, the most significant problems are:
New threats are emerging: