The Government has again been urged by the International Whaling Commission (IWC) to step up efforts to protect the critically endangered Maui's dolphin.

Members of the IWC's scientific committee, meeting in Bled, Slovenia, called upon the New Zealand Government to commit to specific population increase targets and timelines for the conservation of Maui's dolphins.

It's estimated that there are only 55 Maui's dolphins older than one year left in their native range.

The subspecies of Hector's dolphins, found in shallow coastal waters up to depths of 100 metres off the North Island's west coast, have become a symbol for environmentalists challenging gill netting and trawling by commercial fishers, and Government oil and gas exploration block offers in habitat areas.

Presently, the Government has in place a range of set net, trawling and drift net restrictions throughout the dolphins' habitat, while there are also restrictions on seabed mining and acoustic seismic survey work within the boundaries of the West Coast North Island Marine Mammal Sanctuary, which was extended in 2013 to include more of the Maui dolphin's range in the Taranaki area.

The Government was also reviewing a threat management plan already in place for the dolphins, with the programme to be informed by a marine research and advisory group of scientific and stakeholder experts.

In its latest report, released today, the IWC Scientific Committee welcomed new research around the dolphins' welfare but pointed out that no new management actions had been enacted since 2013.

"Given the information presented this year, the committee concludes, as it has repeatedly in the past, that existing management measures in relation to bycatch mitigation fall short of what has been recommended previously and expresses continued grave concern over the status of this small, severely depleted subspecies," members reported.

"The human-caused death of even one individual will increase the extinction risk."

In its recommendations, the committee re-emphasised that the "critically endangered status of this subspecies and the inherent and irresolvable uncertainty surrounding information on most small populations point to the need for precautionary management".

Further, it re-iterated its previous recommendation that "highest priority" should be assigned to immediate management actions to eliminate bycatch of Maui dolphins, including closures of any fisheries within the range of Maui dolphins that were known to pose a risk of bycatch to dolphins.

Thirdly, it noted that the confirmed current range extended from Maunganui Bluff in the north to Whanganui in the south, offshore to 20 nautical miles, and it included harbours.

"Within this defined area, fishing methods other than set nets and trawling should be used.

"The Committee again respectfully urges the New Zealand Government to commit to specific population increase targets and timelines for Maui dolphin conservation, and again respectfully requests that reports be provided annually on progress towards the conservation and recovery goals."

WWF-New Zealand's head of campaigns, Peter Hardstaff, said the conclusions of the international science panel were clear: "more incremental steps and more research are not good enough".

"We need action to fully protect Maui dolphins across their entire range. The government should do the maximum possible, rather than the minimum it can get away with."

Mr Hardstaff called on the Government to help affected fishers transition to dolphin-friendly methods and extend the ban on set netting and traditional trawling to cover all of the Ma ui dolphins’ known range.

"The world is watching us, we need to do the right thing and save these dolphins, which are only found in New Zealand, with an estimated 55 adults left."

The call comes amid fresh efforts by prominent New Zealanders to get more action on the issue.

The Kiwi singer-songwriter Jamie McDell recently penned and recorded a new track, Son of the Ocean, enlisting 55 young New Zealanders to join her on vocals, while freediver William Trubridge is also calling for better protection.